Self-Study Modules on 

Tuberculosis, 6-9

Module 8

Contact Investigations for 

Tuberculosis

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention 

Division of Tuberculosis Elimination 

Atlanta, Georgia 

2014
Module 8—Contact Investigations for Tuberculosis 

2

Contents 

 Background

 Objectives

 New Terms

 Introduction to TB Contact Investigations

 Systematic Approach to TB Contact Investigations

 Assessment and Management of TB Contacts

 TB Contact Investigations in Congregate Settings

 Conducting Source Case Investigations

 Additional Resources

 Answers to Study Questions

 Case Study Answers
Module 8—Contact Investigations for Tuberculosis 

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Background 

In this module, you will learn about tuberculosis (TB) contact investigations. 

Persons who have been exposed to a case* of infectious TB disease are known as TB 

contacts. A TB contact investigation is a TB control strategy used to identify, find, and 

assess TB contacts and provide appropriate treatment for latent TB infection (LTBI) or 

TB disease, if needed. Effective contact investigations interrupt the spread of TB in 

communities and help prevent outbreaks of TB. 

Guidelines for TB contact investigations and management of TB contacts were 

published in 2005. For more detailed information, please refer to the Centers for 

Disease Control and Prevention (CDC) Guidelines for the Investigation of Contacts of 

Persons with Infectious Tuberculosis, available from the CDC website 

(www.cdc.gov/tb). 

* Please note that throughout this module the term “case” will be used instead of 

“patient” to describe persons with TB disease. Although “case” may seem impersonal, 

the rationale for using it is to avoid confusion with contacts who may also be 

considered “patients” if they are found to have LTBI or TB disease.

Objectives 

After working through this module, you will be able to

1. Define a TB contact investigation. 

2. State the goals of a TB contact investigation. 

3. Describe the systematic approach to TB contact investigations. 

4. Define a TB source case investigation. 

define explain list describe
Module 8—Contact Investigations for Tuberculosis 

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New Terms 

New terms introduced in this module are included below. Please refer to the Self-Study 

Modules 1-5 Glossary if you encounter unfamiliar terms related to TB that are not 

defined in the glossary below.

case— a person with suspected or 

confirmed TB disease; sometimes 

referred to as an index case or index 

patient

 

case conference— meetings at 

designated intervals for reviewing the 

treatment of TB patients currently under 

care. During a case conference, the case 

manager presents information to 

colleagues about the status of each 

case under medical care and the 

progress of the contact investigation.

 

congregate setting— a setting in which 

a group of persons reside, meet, or 

gather either for a limited or extended 

period of time in close physical 

proximity. Examples include prisons, 

nursing homes, schools, and homeless 

shelters.

 

contacts— persons exposed to 

someone with infectious TB disease, can 

include family members, roommates or 

housemates, close friends, coworkers, 

classmates, and others

 

contact investigation— a systematic 

process to identify persons (contacts) 

who were exposed to someone with 

infectious TB disease; assess contacts 

for infection with M. tuberculosis and 

TB disease; and provide contacts with 

treatment for latent TB infection or TB 

disease, if necessary

 

degree of infectiousness— physical or 

environmental characteristics that can 

affect ability to transmit M. tuberculosis

 

exposure period— the timeframe during 

which a contact may have been infected 

with M. tuberculosis

 

field visit— visiting a TB case’s 

residence, congregate settings, and 

other places where the TB case spent 

time while infectious. A field visit can 

also be used to locate or meet contacts.

 

genotype— distinct genetic pattern of 

an organism

genotyping— a laboratory-based 

method that can determine the genetic 

pattern of the strain of M. tuberculosis

that caused TB disease in a person 

 

index case— the initial TB case that 

prompts a contact investigation 

 

 
Module 8—Contact Investigations for Tuberculosis 

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infectious— refers to a disease that is 

capable of being spread; a person who 

has infectious TB disease expels 

droplets containing M. tuberculosis into 

the air when he or she coughs, sneezes, 

speaks, or sings 

 

infectious period— time during which a 

TB case is potentially capable of 

transmitting M. tuberculosis

 

location-based investigation— an 

approach for conducting contact 

investigations onsite at a location where 

the TB case spent time while infectious. 

The purpose is to identify and assess 

potential TB contacts at that location. 

 

pre-interview phase— reviewing 

existing information about the TB case 

before the first interview; typically this 

is the first step in the systematic 

approach to contact investigation 

 

prevalence of TB infection— the 

percentage of persons infected with M. 

tuberculosis within a defined population 

 

priority contacts— contacts who are at 

most risk for TB infection or disease 

 

proxy— a person interviewed in place of 

a TB case. Potential proxies include 

family members, close friends, or other 

persons who know the person well. A 

proxy is used if the TB case is deceased, 

physically or mentally unable to 

participate in interviews, very young, or 

unable to be located 

 

proxy interview— an interview with 

persons (proxies) who are familiar with 

the TB case’s practices, habits, and 

behaviors

secondary case— an instance of TB after 

a known exposure, usually related to 

the index case in an investigation 

 

secondary transmission— when any of 

the secondary case’s contacts are found 

to have latent TB infection or TB disease 

 

source case— a person with TB disease 

who is responsible for transmitting M. 

tuberculosis to another person or 

persons 

 

source case investigation— a method 

used to identify a source case; usually 

done when a young child is found to 

have TB disease 

 

TB genotyping information 

management system (TB GIMS)— a 

secure CDC-sponsored online national 

database of M. tuberculosis genotyping 

and TB case information 

 

 
tumor necrosis factor-alpha (TNFalpha) antagonists, inhibitors, or 

blockers— medications used to treat 

inflammatory or autoimmune diseases 

such as rheumatoid arthritis, Crohn’s 

disease, psoriatic arthritis, and juvenile 

rheumatoid arthritis 

 

window period— the time between the 

contact’s last exposure to the TB case 

and when a TST or IGRA can reliably 

detect infection with M. tuberculosis

window period prophylaxis— treatment 

for latent TB infection that is given to 

high-risk contacts who have an initial 

negative test result for TB infection less 

than 8 to 10 weeks after their last TB 

exposure

 

 
Module 8—Contact Investigations for Tuberculosis 

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Introduction to TB Contact 

Investigations 

Conducting contact investigations is a priority for tuberculosis (TB) programs in the 

United States. The goals of a contact investigation are to successfully stop TB 

transmission and prevent future cases and outbreaks of TB disease. It is important to 

remember that every TB case started as a TB contact.

The goals of a contact investigation are to successfully stop TB 

transmission and prevent future cases and outbreaks of TB disease. 

What is a TB Contact Investigation? 

A TB contact investigation is a systematic process to 

1. Identify persons (contacts) exposed to a person with infectious TB disease (a 

case) 

2. Assess contacts for infection with M. tuberculosis and TB disease 

3. Provide appropriate treatment for contacts with latent TB infection (LTBI) or 

TB disease 

Who are TB Contacts? 

Contacts are persons who have shared airspace with a person with infectious TB 

disease. These persons may include household members, friends, coworkers, 

classmates, and others. During a contact investigation, public health investigators 

identify contacts by interviewing the TB case and visiting places where the case spent 

time while infectious. 

Contacts are persons who have shared airspace with a person with 

infectious TB disease. 

Why is it Important to Identify and Assess TB Contacts? 

It is important to quickly identify, find, and assess contacts for TB infection and 

disease. Approximately 1% of all TB contacts have TB disease at the time of the contact 
Module 8—Contact Investigations for Tuberculosis 

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investigation and are in need of treatment. Additionally, about 20% to 30% of TB 

contacts are infected with M. tuberculosis and are at risk for developing TB disease if 

not diagnosed and treated for LTBI.

Contacts infected with M. tuberculosis who are at particularly high risk for developing 

TB disease rapidly include

 Children younger than 5 years of age 

 Persons with weakened immune systems due to 

o HIV infection

o Immunosuppressive therapy, including tumor necrosis factor-alpha (TNFalpha) antagonists, prolonged use of high-dose adrenocorticosteroids, or 

medications received after organ transplantation 

Contacts who have either LTBI or TB disease should be offered the appropriate 

treatment unless there is a compelling reason not to do so (e.g., the contact has 

hepatitis or end-stage liver disease). For a contact investigation to be considered 

successful, contacts should complete treatment if they have LTBI or TB disease.

For a contact investigation to be considered successful, contacts 

should complete treatment if they have LTBI or TB disease. 

Who is Responsible for Conducting TB Contact Investigations? 

In the United States, state and local health departments are legally responsible for the 

prevention and control of TB in their communities. Thus, they are accountable for 

ensuring contact investigations are performed for TB cases reported in their 

jurisdictions, even when patients are receiving care outside the health department. 

Health departments are accountable for ensuring contact 

investigations are performed for TB cases reported in their 

jurisdictions, even when patients are receiving care outside the health 

department. 

Although health departments are responsible for conducting contact investigations, 

some steps of a contact investigation may be given to persons or programs outside of 

the health department. For example, if transmission of M. tuberculosis occurs at a 

healthcare facility, the contact investigation may include hospital epidemiologists and 

infection control professionals. Whenever contact investigation activities are delegated, 
Module 8—Contact Investigations for Tuberculosis 

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the health department should work with those involved to ensure that the local policies 

and procedures are followed. 

Whenever contact investigation activities are delegated, the health 

department should work with those involved to ensure that the local 

policies and procedures are followed. 

For some contact investigations, there may be areas and programs involved that are 

not under the jurisdiction of state or local health departments. For example, some 

contact investigations may involve military bases, federal prisons, diplomatic missions, 

or American Indian or Alaska Native tribal reservations. If an area or program has its 

own healthcare system or TB control program, state and local health departments can 

offer technical consultation and support.

For sites without their own healthcare system or TB control program, agreements can 

be made with authorities about how to handle the public health response. In tribal 

areas, health departments should coordinate with both tribal leadership and the 

system that is providing healthcare to tribal members, such as the Indian Health 

Service (IHS) or tribally run healthcare systems.

The Centers for Disease Control and Prevention (CDC) is available to assist in the 

coordination of contact investigations that involve tribal jurisdictions, multiple 

jurisdictions, or international jurisdictions.

Which TB Cases Require a Contact Investigation? 

Cases with Infectious Forms of TB Disease 

Confirmed TB Cases

A contact investigation is required for all confirmed cases that have infectious forms of 

TB disease (e.g., TB disease of the lungs, airways, or larynx). 

A contact investigation is required for all confirmed cases that have 

infectious forms of TB disease (e.g., TB disease of the lungs, airways, 

or larynx). 

Suspect TB Cases 

The contact investigation process should be started for persons suspected of having 

infectious TB disease, even before confirmation. This includes persons with positive 
Module 8—Contact Investigations for Tuberculosis 

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sputum smears and a positive nucleic acid amplification test result. For persons with 

positive sputum smears and a negative nucleic acid amplification test result, a contact 

investigation is not indicated.

The contact investigation process should be started for persons 

suspected of having infectious TB disease, even before confirmation. 

For suspect cases with negative sputum smears or sputum smears not performed, the 

contact investigation process should be started if the case has abnormal chest x-ray 

findings consistent with TB disease. 

For suspect cases with negative sputum smear results and no pulmonary cavities, a 

contact investigation should only be considered for certain circumstances, such as if 

the suspect was identified during an outbreak or source case investigation that 

included vulnerable or susceptible contacts. 

If it is later determined that the suspect case does not have infectious TB disease, the 

contact investigation should be stopped.

If it is later determined that the suspect case does not have infectious 

TB disease, the contact investigation should be stopped. 

Cases with Noninfectious Forms of TB Disease 

Cases with noninfectious forms of TB disease generally do not require a contact 

investigation. This includes cases that only have extrapulmonary TB disease (e.g., TB 

disease in the brain, the kidneys, or the bones and joint). 

Cases with noninfectious forms of TB disease generally do not 

require a contact investigation. 

Cases Younger than 10 Years of Age 

In most instances, a contact investigation is not necessary for children younger than 10 

years of age. This is because they are less likely to transmit M. tuberculosis. If the case 

is younger than 5 years of age, a source case investigation might be indicated (for 

more information, see the Source Case Investigations section of this module, page 90).
Module 8—Contact Investigations for Tuberculosis 

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For more specific information on initiating a contact investigation, refer to the CDC 

Guidelines for the Investigation of Contacts of Persons with Infectious Tuberculosis, 

available from the CDC website (www.cdc.gov/tb).

In most instances, a contact investigation is not necessary for 

children younger than 10 years of age. 

When Should the TB Contact Investigation Begin? 

In all U.S. jurisdictions, clinicians are required to rapidly report TB disease or a 

suspicion of TB disease to public health authorities. The first few steps of the TB 

contact investigation process should start as soon as a suspected or confirmed 

infectious TB case comes to public health attention. This includes reviewing medical 

information and interviewing the case within one working day after the case is reported 

to the health department. 

The first few steps of the TB contact investigation process should 

start as soon as a suspected or confirmed infectious TB case comes 

to public health attention. 

It is important to respond promptly because

 Some contacts may already have TB disease and are in need of treatment;

 Some contacts could be at risk for rapid development of TB disease;

 Some contacts may become more difficult to locate as time goes by, such as 

homeless persons;

 There could be ongoing transmission of M. tuberculosis; and

 Cases may have difficulty remembering all of their contacts as time goes by.

Contact investigations initiated for suspect TB cases should be stopped if it is later 

determined that the person does not have infectious TB disease. 

 
Module 8—Contact Investigations for Tuberculosis 

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Study Questions 8.1 – 8.4 

8.1 What is a TB contact investigation? 

 

 

 

 

 

 

8.2 What are the goals of a TB contact investigation? 

 

 

8.3 Which TB cases require a contact investigation? 

 

 

 

 

 

 

8.4 Who is responsible for conducting TB contact investigations? 

 

Answers to study questions are on pages 99-105
Module 8—Contact Investigations for Tuberculosis 

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Case Study 8.1 

You are a TB case manager at a busy clinic. Two new TB cases have been 

assigned to you. Indicate which case(s) require a contact investigation and 

note the reason why you made your decision.

 Jose is a 35-year-old agricultural worker diagnosed with extrapulmonary 

TB of the kidneys. He lives with his wife in a small, rented house in a rural 

area. 

 Dale is a 72-year-old widower who lives alone. He drives himself to the 

local retirement center for bingo and poker four times a week. He was 

recently evaluated for TB disease by his physician because he complained 

of having a cough, shortness of breath, fatigue, and weight loss. His 

sputum smears were positive and his culture results are pending. Dale’s 

chest x-ray shows a cavity in the right upper lobe of his lungs. The 

physician suspects TB and started Dale on a four-drug regimen. 

Answers to case studies are on pages 106-112
Module 8—Contact Investigations for Tuberculosis 

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How Should TB Contact Investigations be Prioritized? 

Because of limited resources and competing demands, health departments may not be 

able to complete the contact investigation process for all confirmed or suspected 

infectious TB cases promptly. Thus, health departments may need to prioritize among 

contact investigations and dedicate resources to those considered a higher priority. 

If a health department needs to prioritize between contact investigations, the focus 

should be on contact investigations where the likelihood of transmission is high and 

contacts are at an increased risk for rapid development of TB disease. 

In general, priority should be given to contact investigations involving

 Cases that are likely to be highly infectious 

 Settings where transmission of M. tuberculosis is likely 

 Contacts at high risk for rapid development of TB disease if infected with M. 

tuberculosis

If a health department needs to prioritize between contact 

investigations, the focus should be on contact investigations where 

the likelihood of transmission is high and contacts are at an 

increased risk for rapid development of TB disease. 

Highly Infectious Cases 

Transmission of M. tuberculosis depends on a variety of factors, but it is more likely to 

occur when a case is highly infectious. Highly infectious cases generally have one or 

more of the following characteristics: 

 Pulmonary, laryngeal, or pleural TB

 Positive sputum smear results

 Cavities on chest x-ray

 Actions that can increase the likelihood of transmission

o Coughing

o Sneezing

o Singing

For example, a case with pulmonary TB who was coughing for three months before 

receiving treatment and who has positive sputum smears is more likely to be infectious 
Module 8—Contact Investigations for Tuberculosis 

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than a case who has negative sputum smears and has rarely been coughing. Therefore, 

the first case would be considered a higher priority for a contact investigation.

Transmission of M. tuberculosis depends on a variety of factors, but 

it is more likely to occur when a case is highly infectious. 

Settings Where Transmission of M. tuberculosis is Likely 

Another factor to consider when prioritizing among contact investigations is the 

setting in which transmission may have occurred. Transmission is more likely if there 

is a high concentration of M. tuberculosis in the air. The concentration of bacteria in 

the air is affected by the setting’s

 Size

 Ventilation 

 Air-cleaning system 

M. tuberculosis is more likely to be transmitted in small, crowded spaces that do not 

have adequate airflow. For example, transmission is more likely in a small office with 

little or no ventilation than it is in a large, well-ventilated grocery store. Settings with 

air-cleaning systems such as high-efficiency particulate air (HEPA) filters and 

ultraviolet lights can decrease the concentration of M. tuberculosis in the air. (For more 

information, refer to Module 5, Infectiousness and Infection Control.)

In addition to the size, ventilation, and air-cleaning systems of the setting, it is also 

important to consider activities that have occurred in the setting that can increase the 

likelihood of transmission. For example, medical procedures such as bronchoscopy, 

sputum induction, TB wound irrigation, or autopsy of TB cases can produce a high 

concentration of M. tuberculosis in the air. Therefore, contact investigations involving 

settings where these procedures take place should be considered a priority.

Transmission is more likely if there is a high concentration of M. 

tuberculosis in the air. 

Contacts at High Risk for Rapid Development of TB Disease if Infected with M. 

tuberculosis 

Contacts who are at a particularly high risk for rapidly developing TB disease after 

infection with M. tuberculosis include

 Children younger than 5 years of age 
Module 8—Contact Investigations for Tuberculosis 

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 Persons with weakened immune systems due to

o HIV infection

o Immunosuppressive therapy, including TNF-alpha antagonists, prolonged 

use of high-dose adrenocorticosteroids, or medications received after 

organ transplantation 

Any contact investigation involving these persons should be given priority.

Who Conducts the TB Contact Investigation? 

A TB contact investigation involves many different steps and procedures. Depending on 

the program, the activities of the contact investigation may be conducted by an 

individual or a contact investigation team.

The staff involved in conducting a contact investigation can include

 Case managers

 Field investigators

 Outreach workers

 Epidemiologists and surveillance staff

 Program managers

The actual job titles for team members may vary by jurisdiction. In some jurisdictions, 

one staff member may fill several roles. Ideally, one person should be assigned 

responsibility for the overall management of the investigation to ensure all activities of 

the contact investigation are conducted. In certain situations, infection control 

professionals or other staff from facilities where exposure occurred may be involved as 

part of the contact investigation team.

For the purposes of this module, the person responsible for conducting the contact 

investigation will be referred to as the “contact investigator.”

Ideally, one person should be assigned responsibility for the overall 

management of the investigation to ensure all activities of the 

contact investigation are conducted. 

 
Module 8—Contact Investigations for Tuberculosis 

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What Knowledge and Skills are Necessary to Conduct a TB Contact 

Investigation? 

To conduct a TB contact investigation, it is ideal for the contact investigator and others 

on the team to have the following knowledge and skills:

 A basic understanding of TB transmission and pathogenesis (for more 

information, refer to Module 1, Transmission and Pathogenesis of Tuberculosis)

 Effective communication skills to build trust and rapport with the case during 

interviews (for more information, refer to page 37 of this module)

 Data management and data analysis skills

 An understanding of TB genotyping

 

Data Management and Data Analysis 

To successfully conduct a contact investigation, investigators need to have skills in 

data management and data analysis. This is because contact investigations typically 

involve a large amount of demographic, medical, and epidemiologic information that 

needs to be systematically collected, organized, and analyzed. This data is typically 

used for case management, epidemiologic analysis, and program evaluation. 

When conducting a contact investigation, public health programs need to determine

 Which data needs to be collected and why 

 Who is responsible for collecting and how

 How data is to be managed and safeguarded

Data management during a TB contact investigation can be very time consuming. 

Therefore, the benefits of having the data must justify the level of effort and resources 

required.

Contact investigations typically involve a large amount of 

demographic, medical, and epidemiologic information that needs to 

be systematically collected, organized, and analyzed. 

An Understanding of TB Genotyping 

TB genotyping is a laboratory-based method that can determine the genetic pattern of 

the strain of M. tuberculosis that caused TB disease in a person. Each strain has a 

distinct genetic pattern, or genotype. Genotyping is done for culture-positive cases of 

TB disease.
Module 8—Contact Investigations for Tuberculosis 

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In the United States, genotyping information on individual cases is available to state 

and local health departments through the TB Genotyping Information Management 

System (TB GIMS), a secure CDC-sponsored online national database of genotyping 

and case information. 

Typically, genotype information will not be available during the early stages of a 

contact investigation. When it does become available, the results can help confirm, 

disprove, or detect connections among cases. If two cases have matching genotypes, 

they may be connected even if the connection is not recent or obvious. For example, 

two persons whose TB strains match by genotype might not know one another, but 

they may have both been exposed to the same infectious case several years earlier.

(For more information on genotyping, refer to Module 9, Tuberculosis Outbreak 

Detection and Response.)

Typically, genotype information will not be available during the early 

stages of a contact investigation. When it does become available, the 

results can help confirm, disprove, or detect connections among 

cases. 
Module 8—Contact Investigations for Tuberculosis 

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Study Question 8.5 

8.5 Which TB contact investigations should be given priority? 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105
Module 8—Contact Investigations for Tuberculosis 

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Systematic Approach to TB Contact 

Investigations 

How is a TB Contact Investigation Conducted? 

Contact investigations should be conducted using a systematic process that includes 

the following 10 steps: 

1. Review existing information about the case 

2. Determine an initial estimate for the infectious period and estimate the degree 

of infectiousness 

3. Interview the case 

4. Review information and develop a plan for the investigation 

5. Refine the infectious period and degree of infectiousness 

6. Prioritize contacts 

7. Conduct field visits 

8. Conduct contact assessments 

9. Determine whether to expand or conclude an investigation 

10.Evaluate the contact investigation activities 

The actual sequence and timing of contact investigation steps and activities may vary 

from one investigation to another. Moreover, local public health programs may have 

additional guidance on policies and procedures for conducting contact investigations 

within their jurisdictions. These policies and procedures should be written and 

available to staff responsible for conducting contact investigations. Regardless of 

variations among local program policies, an effective investigation will include all of 

the above 10 steps. This section of the module will provide an overview of each of the 

steps.

The actual sequence and timing of contact investigation steps and 

activities may vary from one investigation to another. 
Module 8—Contact Investigations for Tuberculosis 

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Step 1.Review Existing Information about the Case 

As soon as a suspected or confirmed case of TB comes to public health attention, 

contact investigators should begin gathering and reviewing all existing information 

about the case. 

Existing information can help the investigator

 Estimate the infectious period 

 Estimate the degree of infectiousness 

 Identify potential contacts

 Identify potential exposure locations

 Conduct effective interviews

Reviewing the existing information is sometimes referred to as the pre-interview 

phase.

As soon as a suspected or confirmed case of TB comes to public 

health attention, contact investigators should begin gathering and 

reviewing all existing information about the case.

Information to Collect and Review before the Initial Interview with the Case 

The following information should be collected and reviewed during the pre-interview 

phase:

Medical Information 

 Site(s) of TB disease

 Current TB treatment regimen 

 TB symptoms and estimated onset date 

 Chest x-rays or other diagnostic imaging dates and results 

 Tuberculin skin test (TST) or interferon-gamma release assay (IGRA) dates and 

results 

 Sputum smear and culture dates and results

 Nucleic acid amplification (NAA) test dates and results

 Genotype results (if available)

 HIV test dates and results

 Details about prior diagnosis with LTBI or TB disease, and any treatment 
Module 8—Contact Investigations for Tuberculosis 

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 Medical risk factors that could have increased the case’s risk for infection with 

M. tuberculosis or development of TB disease

 

Demographic and Social Information 

 Name and aliases

 Date of birth

 Gender

 Addresses and telephone numbers

 Preferred language

 Next of kin, emergency contacts, and names of parents or guardians, if the case 

is a minor

 Details about any known TB exposures

 History of substance use, mental illness, or any other issues that could affect 

the interview or the contact investigation

 Social or behavioral risk factors that could have increased the case’s risk for 

infection with M. tuberculosis or development of TB disease

 Contact names, particularly children or persons with weakened immune 

systems, who live with or frequently spend time with the case

 Recent travel or immigration

 History of jail or homelessness

Some of the above information may not be available during the pre-interview phase. If 

information cannot be obtained at this step, the investigator should obtain it during 

the interview phase.

Sources of Information for TB Cases 

Pre-interview information can be obtained from the following sources:

 Public health records

 Medical records

 Discussions with the case’s clinicians

 Tuberculosis Genotyping Information Management System (TB GIMS)

Public Health Records 

Contact investigators should cross-check locally available TB registries and 

surveillance databases to determine if the case was previously included in a TB contact 
Module 8—Contact Investigations for Tuberculosis 

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investigation or diagnosed with LTBI or TB disease. Information from the Report of 

Verified Case of Tuberculosis (RVCT) should also be reviewed. 

Additional information about the case’s HIV status and any prior TB exposure, 

assessment, or treatment may also be found by reviewing health department’s HIV and 

STD surveillance records. 

 

Medical Records 

All available and relevant medical records for the case, including any from the health 

department, hospital, clinic, and if applicable, long-term care facility or correctional 

facility, should be reviewed.

For cases who were hospitalized while infectious, nurse progress notes may include 

the names of family and friends who visited. In addition, health insurance information 

may provide the work location of the case. This information can help identify potential 

contacts and can be used as prompts during case interviews. 

 

Discussions with the Case’s Clinicians 

Speaking with the case’s private or public clinicians can help clarify information 

obtained from medical records as well as provide additional details about the case. 

 

Tuberculosis Genotyping Information Management System (TB GIMS) 

Typically, genotype information will not be available during the early stages of a 

contact investigation. Genotyping information for specific cases is available to state 

and local health departments through TB GIMS. Local health departments can access 

genotyping data in various ways, usually either through TB GIMS directly or from the 

state TB program.

For more information about TB GIMS, please refer to the CDC website on TB GIMS 

(www.cdc.gov/tb/publications/factsheets/statistics/gims.htm).

Step 2: Determine an Initial Estimate for the Infectious Period and 

Estimate the Degree of Infectiousness 

The infectious period is the time during which a case is potentially capable of 

transmitting M. tuberculosis. As there is no well-established method to determine the 

exact start date of the infectious period, it must be estimated. Estimating a case’s 
Module 8—Contact Investigations for Tuberculosis 

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infectious period helps to focus investigation efforts on identifying contacts who were 

most likely exposed to M. tuberculosis while the case was infectious.

The infectious period is the time during which a case is potentially 

capable of transmitting M. tuberculosis.

Estimating a case’s infectious period helps to focus investigation 

efforts on identifying contacts who were most likely exposed to M. 

tuberculosis while the case was infectious. 

Contact investigators should prepare an initial estimate for the infectious period based 

on information collected during the pre-interview phase. This initial estimate will be 

revised as additional information becomes available throughout the contact 

investigation process. 

Below is a method to help estimate the infectious period. For more specific information 

on estimating the infectious period, refer to the CDC Guidelines for the Investigation of 

Contacts of Persons with Infectious Tuberculosis, available from the CDC website 

(www.cdc.gov/tb).

Estimating the Start of the Infectious Period for Sputum Smear Positive Cases 

For cases that have positive sputum smears, the minimum start date of the infectious 

period is usually 3 months before the onset of respiratory symptoms (e.g., cough) or 3 

months before the first finding consistent with TB disease, whichever is earlier. 

For example, if the case’s symptoms started on November 1st, the start of the 

infectious period would be August 1st (3 months before the symptoms started). See 

Figure 8.1. 

For cases that have positive sputum smears, the minimum start date 

of the infectious period is usually 3 months before the onset of 

respiratory symptoms (e.g., cough) or 3 months before the first 

finding consistent with TB disease, whichever is earlier. 
Module 8—Contact Investigations for Tuberculosis 

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Some cases may not remember when their TB symptoms began, and others may report 

that they have had no symptoms. In this situation, the start of the infectious period 

should be, at a minimum, 3 months before the first finding consistent with TB disease. 

For example, if a case has had no symptoms, but had a chest x-ray taken on 

September 1st which showed a cavity, the start of the infectious period would be June 

1st (3 months before the chest x-ray).

 

Estimating the Start of the Infectious Period for Sputum Smear Negative Cases 

For TB cases with TB symptoms and negative sputum smear results, the start of the 

infectious period would be 3 months before symptom onset or 3 months before the 

first finding consistent with TB disease, whichever is earlier. 

For TB cases with negative sputum smear results, no symptoms, and no pulmonary 

cavities, the start of the infectious period is 1 month (4 weeks) before TB disease was 

first suspected by a healthcare provider. For example, if the healthcare provider first 

suspected TB disease on September 15th, the infectious period would be 1 month 

before that date (August 15th). See Figure 8.2.

Table 8.1 shows recommendations for estimating the start of the infectious period.

 

 
Module 8—Contact Investigations for Tuberculosis 

26

Table 8.1 

Recommendations for Estimating the Start of the Infectious Period

 

Estimating the End of the Infectious Period 

The infectious period ends when all of the following are met: 

 Effective treatment 2 weeks or longer;

 Diminished symptoms (e.g., coughing less); and 

 Mycobacteriologic response (e.g., decrease in grade of sputum smear positivity).

If a case is returning to a congregate setting, or to any other setting where susceptible 

persons may be exposed, he or she should have at least three consecutive negative 

sputum smear results before being considered noninfectious.

For contact investigation purposes, the infectious period can also end when the case is 

isolated under airborne infection isolation precautions, even if not all of the criteria 

Characteristic of Case 

Recommended Minimum 

Beginning of the Infectious 

Period 

Respiratory TB 

Symptoms 

Sputum Smear 

Positive 

Pulmonary 

Cavity on 

Chest X-ray 

Yes No No

3 months before symptom 

onset or first finding 

consistent with TB disease, 

whichever is longer

Yes Yes Yes

3 months before symptom 

onset or first finding 

consistent with TB disease, 

whichever is longer

No No No

1 month (4 weeks) before 

date of suspected 

diagnosis

No Yes Yes 3 months before finding 

consistent with TB disease
Module 8—Contact Investigations for Tuberculosis 

27

above have been met. This is because these precautions limit the case’s ability to 

transmit M. tuberculosis to additional contacts. 

Figure 8.1 shows an example of how to determine an initial estimate for the beginning 

and end of the infectious period for a case with a positive sputum smear result and 

symptoms of TB disease. In this example, the case had negative sputum smears, no 

symptoms, and over 2 weeks of treatment by December 1st. Therefore, the end of the 

infectious period would be December 1st.

 

Figure 8.1 Example of determining an initial estimate of the infectious period for a 

smear positive case with TB symptoms.

 

Figure 8.2 shows an example of how to determine an initial estimate of the beginning 

and end of the infectious period for a case with a negative sputum smear result, no 

pulmonary cavities, and no symptoms of TB. In this example, the case was isolated on 

September 15th, the same date that TB was first suspected. Therefore, the end of the 

infectious period would be September 15th.
Module 8—Contact Investigations for Tuberculosis 

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Figure 8.2 Example of determining an initial estimate of the infectious period for a 

smear negative case who does not have TB symptoms or a cavity on chest x-ray.

 

Estimating the Degree of Infectiousness 

Estimating the degree of infectiousness of a case helps investigators focus contact 

investigation efforts. The greater the degree of infectiousness, the more likely that 

transmission occurred. 

Estimating the degree of infectiousness of a case helps investigators 

focus contact investigation efforts. The greater the degree of 

infectiousness, the more likely that transmission occurred. 

An initial estimate for the degree of infectiousness can be made during the preinterview phase. If an estimate is made, it may need to be revised after the interview 

with the case and as the investigation continues. 

Table 8.2 presents factors that should be taken into consideration when determining 

the degree of infectiousness of a case.

 
Module 8—Contact Investigations for Tuberculosis 

29

Table 8.2 

 Factors Associated with Infectiousness and Noninfectiousness 

Factors Associated with More Infectiousness Factors Associated with Less Infectiousness

Presence of a cough No cough 

Cavity in the lung No cavity in the lung 

Acid-fast bacilli on sputum smear No acid-fast bacilli on sputum smear 

TB of the lungs, airway, or larynx Most extrapulmonary (non-respiratory) TB 

Patient not covering mouth or nose when 

coughing

Patient covering mouth or nose when coughing

Not receiving adequate treatment or having 

prolonged illness

Receiving adequate treatment for 2 weeks or 

longer 

Undergoing cough-inducing procedures Not undergoing cough-inducing procedures 

Positive sputum cultures Negative sputum cultures

For more information on infectiousness, see Module 5, Infectiousness and Infection 

Control.
Module 8—Contact Investigations for Tuberculosis 

30

Study Questions 8.6 – 8.7 

8.6 What is the infectious period? 

 

 

 

 

 

 

 

 

 

 

 

8.7 When does the infectious period end? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

31

Case Study 8.2 

Calculate the infectious periods for the following TB cases

 Isaac is a 42-year-old man who was hospitalized on December 4th with 

symptoms of fever, night sweats, and cough. He was placed in airborne 

infection isolation. On the same date (December 4th), AFB sputum smears 

were collected and reported as positive with final cultures pending. Chest xrays were taken on December 4th and reported as abnormal with cavitary 

disease. 

 

Isaac was diagnosed with suspected pulmonary TB and appropriate TB 

treatment was started on December 5th. Isaac states that he started 

coughing around November 6th. His symptoms resolved on December 24th. 

Three consecutive sputum AFB smears were negative on February 10th. 

 

 

 

 

 

 Trang is a 52-year-old woman who had a checkup with her primary care 

provider on May 19th. During this visit, she was found to have an abnormal 

chest x-ray. Sputum collected on the same day was reported as AFB smear 

positive with final cultures pending. On May 20th she was diagnosed with 

suspected pulmonary TB, started appropriate treatment, and was put on 

home isolation. Trang claims she never had a cough or any other symptoms. 

Three consecutive induced sputum AFB smears were negative on June 15th, 

June 18th, and June 21st. 

Answers to case studies are on pages 106-112

 
Module 8—Contact Investigations for Tuberculosis 

32

Step 3: Interview the Case 

The foundation of an effective contact investigation is the case interview. If the 

investigator does not communicate well with the case to obtain accurate information, 

persons who need medical assessment and treatment may be missed. To obtain 

complete and accurate information from the case, it is important that the contact 

investigator is trained and skilled in conducting interviews.

The foundation of an effective contact investigation is the case 

interview. If the investigator does not communicate well with the case 

to obtain accurate information, persons who need medical 

assessment and treatment may be missed. 

What is the Main Goal of the Case Interview? 

The main goal of the case interview is to identify contacts who may have been exposed 

to M. tuberculosis. To gather information about contacts, the investigator should ask 

the case 

 Where he or she spent time during infectious period

 What activities or events he or she participated in during infectious period

 Whom he or she spent time with during infectious period

The main goal of the case interview is to identify contacts who may 

have been exposed to M. tuberculosis.

Where the Case Spent Time During Infectious Period 

Asking the case about places where he or she spent time can help determine whom he 

or she spent time with during the infectious period. These places can include locations 

of

 Residence

 Work, school, or volunteer activities

 Social, leisure, religious, or recreation activities

 Illicit or illegal activities

For each place identified, the case should be asked about the

 Amount of time spent in each place

 Characteristics of each place, such as room size, crowding, and whether 

windows were open or closed
Module 8—Contact Investigations for Tuberculosis 

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This information can help the investigator estimate the risk of transmission for each 

place and, thus, prioritize field visits for assessing the various sites. 

Asking the case about places where he or she spent time can help 

determine whom he or she spent time with during the infectious 

period. 

Compiling a list of places is also useful because the case may not always be able to 

provide enough information about each of his or her contacts. This information about

places could then be used to conduct a location-based investigation. For more 

information about conducting a location-based investigation, refer to page 54 of this

module.

What Activities and Social Events the Case Participated in During Infectious Period 

In addition to asking the case about places where he or she has spent time, the 

investigator should ask about activities during the infectious period. It can be helpful 

for the case to outline a typical day starting with getting up in the morning until going 

to bed at night. Asking specifically about participation in activities or special events 

such as parties or holiday celebrations might help the case remember additional

exposure settings and contacts. Reviewing a calendar or appointment book with the 

case could also be helpful for determining travel, holidays, and social events during the 

infectious period.

The investigator should also specifically ask the case if he or she was involved in any 

activities such as volunteering in a nursing home, day care, or hospital, where persons 

who are at high risk for rapid development of TB disease could have been exposed.

The investigator should ask the case about activities during the 

infectious period. It can be helpful for the case to outline a typical 

day starting with getting up in the morning until going to bed at 

night. 

Whom the Case Spent Time with During Infectious Period 

The investigator should ask the case to give the names and aliases of persons with 

whom he or she spent time while infectious. This includes any persons who live in the 

same home or share a sleeping space with the case. Additionally, the investigator 

should identify any persons with whom the case spent a lot of time. The compiled list 
Module 8—Contact Investigations for Tuberculosis 

34

of places and activities should be used to prompt the case to remember persons with 

whom he or she spent time.

The investigator should ask the case to give the names and aliases of 

persons with whom he or she spent time while infectious. 

The case should be asked specifically about any time spent with contacts who

 Have symptoms of TB disease, such as cough or weight loss;

 Are younger than 5 years of age;

 Have a medical condition that weakens the immune system (e.g., HIV or 

immunosuppressive therapy).

Another strategy to identify contacts is to review the case’s cell phone directory and 

online social networking accounts (e.g., Facebook, LinkedIn). This can help the case 

remember friends and events. This should be done with the case’s permission. 

For each contact listed, the investigator should obtain locating information, phone 

number(s), or preferably both so that he or she can be notified about their exposure to 

TB.

If the case does not have enough information to help identify or find some contacts,

the investigator should ask him or her for ideas on how to gather the information from 

other sources (e.g., a work roster).

Investigators should be aware that the case may be reluctant to talk about some or all 

of their contacts. For example, a case may not want to identify people who use illegal 

drugs, reside in the United States illegally, or he or she may be worried about 

confidentiality. The interviewer should be sensitive to the case’s fears, explain the 

importance of testing contacts, and assure the case that all information will be kept 

confidential.

What Are Additional Objectives of the Case Interview? 

Additional objectives of the case interview are to 

 Discuss the contact investigation process;

 Educate about TB disease; and 

 Confirm and expand upon information obtained from the pre-interview phase. 
Module 8—Contact Investigations for Tuberculosis 

35

Additional objectives of the case interview are to discuss the contact 

investigation process, educate the case about TB disease, and 

confirm and expand upon information obtained from the preinterview phase. 

Discuss the Contact Investigation Process 

When interviewing a case, the investigator should go over the process and the reasons 

for the interview. A case who understands why and how a contact investigation 

happens is more likely to provide information to help find his or her contacts. The 

investigator should ensure that the case understands that all information provided will 

remain confidential to the extent possible and that information will be shared with only 

persons who need to know (e.g., other public health personnel). The case should be 

informed that sometimes despite best efforts their TB status may be inadvertently 

disclosed to others. For example, the case’s friend, family member, or co-worker may 

share information to others. The case and the investigator should discuss this 

possibility and be prepared to address the situation if privacy is not maintained. To 

prevent breaches in confidentiality, the case should be advised to inform only persons 

he or she trusts about their TB diagnosis. (For more information on confidentiality, see 

Module 7, Patient Rights and Confidentiality in Tuberculosis Control.)

Educate about TB Disease 

During the interview, it is important to assess the case’s knowledge about TB. The 

case may have little to no knowledge or have misconceptions about TB. The case 

interview can be an opportunity to educate the case about TB transmission and 

treatment. A case who understands his or her TB diagnosis and how TB is 

transmitted is more likely to be invested in the contact investigation, as well as 

their TB treatment. Patient education materials may be useful to bring to the 

interview. (For more information on patient education strategies, refer to Module 6, 

Managing Tuberculosis Patients and Promoting Adherence.)

A case who understands why and how a contact investigation 

happens is more likely to provide information to help find their 

contacts. 

 
Module 8—Contact Investigations for Tuberculosis 

36

Confirm and Expand Upon Information Obtained from the Pre-Interview Phase 

The case interview is also an opportunity to confirm and expand upon information 

collected during the pre-interview phase. The case may be able to provide additional 

information and details that were not captured by the medical record review.

The investigator should specifically ask about any TB symptoms and TB history, as well 

as confirm personal and medical information. Any additional information about the 

onset of symptoms can be used to refine the estimated infectious period.

When and Where Should the Case Interview be Conducted? 

The initial interview should be within one working day after an infectious case is 

reported to the health department. This allows the investigator to find contacts who 

may already have TB disease as soon as possible.

The initial interview should be within one working day after an 

infectious case is reported to the health department. 

A re-interview should be scheduled for 1–2 weeks after the initial interview so that the 

case will have had time to adjust to their TB diagnosis and treatment. The re-interview 

is also an opportunity to continue to build a trusting relationship between the case and 

the investigator and to learn about more contacts.

Additional interviews should be scheduled as needed. Re-interviews do not need to be 

formal. Investigators can continue to collect information throughout the process. For 

example, some re-interviews can be conducted during directly observed therapy (DOT) 

visits or field visits. 

The interviews should be done in person (see Figure 8.3). The interviews can be in the 

hospital, the TB clinic, the case’s home, or any other location that is convenient for the 

case and that respects his or her privacy. Health care workers should follow infection 

control precautions while interviewing someone who has potentially infectious TB.

Interviews can be in the hospital, the TB clinic, the case’s home, or 

any other location that is convenient for the case and that respects 

his or her privacy. 

 
Module 8—Contact Investigations for Tuberculosis 

37

 

Figure 8.3 Contact investigator interviewing a case who is no longer considered 

infectious.

 

What are Some Strategies for Conducting Effective Interviews? 

Some strategies for effective interviews are summarized in Table 8.3. Additionally, 

several training resources are available for enhancing interviewing skills, including 

Effective TB Interviewing for Contact Investigation: Self-Study Modules and the 

Effective TB Interviewing for Contact Investigations DVD, both available from the CDC 

website (www.cdc.gov/tb/education).

Building Trust and Rapport 

The most important skill in conducting an interview is the ability to build trust and 

rapport with the case. This can help ensure that the case is comfortable in providing 

information that is important to the contact investigation. For example, a case may feel 

stigma associated with TB disease and may be reluctant to share the names of his or 

her contacts. Additionally, a case may be involved in illegal activities and not feel 

comfortable sharing information about those activities and contacts with the 

investigator. Thus, it is important that the contact investigator builds a trusting 

relationship with the case by finding common ground, using effective 

communication skills, maintaining confidentiality, and displaying respect and 

empathy. Finding common ground typically does not have to do with the case 

having TB disease. For example, the investigator and the case may find that they 
Module 8—Contact Investigations for Tuberculosis 

38

have similar hobbies and interests. (Refer to Module 6, Managing Tuberculosis 

Patients and Promoting Adherence, for more information regarding trust and 

rapport.)

The most important skill in conducting an interview is the ability to 

build trust and rapport with the case. 

Using Open-Ended Questions 

During the interview, contact investigators should use open-ended questions to gather 

information from the case. Open-ended questions encourage discussion because they 

encourage more than a “yes” or “no” response. The questions in Table 8.4 are 

examples of open-ended questions that can be used during interviews. 

During the interview, contact investigators should use open-ended 

questions to gather information from the case. 

Using an Interview Checklist 

To ensure that interview objectives are being met, an interview checklist can be used. 

The use of an interview checklist can prompt the investigator to obtain information on 

places and activities, as well as remind the investigator to educate the case about TB 

and the contact investigation process. Although the use of a checklist can help ensure 

that all of the interview objectives are systematically met, it is important to remember 

that the interview is a conversation between the interviewer and the case. The 

interviewer should be flexible and allow for a natural flow of the conversation. The 

interview checklist should not be a distraction while trying to build rapport with the 

case. Furthermore, the investigator should be alert to other information that may not 

be reflected on the checklist. Figure 8.4 shows an example of a checklist that can be 

used during a case interview.

Although the use of a checklist can help ensure that all of the 

interview objectives are systematically met, it is important to 

remember that the interview is a conversation between the 

interviewer and the case. 

Depending on the situation, other tools may be helpful during an interview. For 

example, some jurisdictions that encounter cases among homeless populations may 
Module 8—Contact Investigations for Tuberculosis 

39

have a list of temporary shelters that can be used to help prompt the investigator to 

ask the case about each location.

Table 8.3 

Strategies for Conducting Effective TB Case Interviews 

 Have a clear understanding of the objectives of the interview.

 Plan the interview so that each objective is given adequate time.

 Ensure the interview takes place under conditions that protect the privacy of 

the case and encourage effective communication.

 Arrange for the assistance of an interpreter if you do not speak the same 

language as the case.

 Establish the foundation for an effective working relationship based on trust 

and respect. 

 Explain what a contact investigation is, how a contact investigation protects 

contacts from getting sick with TB disease, and what the case can do to help.

 Begin with an assessment of the case’s knowledge, feelings, and beliefs about 

TB.

 Remain objective, open-minded, and nonjudgmental.

 Ask open-ended questions and listen carefully to the case’s responses.

 Recognize and address the case’s fears and concerns about TB.

 Use opportunities that arise during the interview to educate the case about TB.

 

 

 
Module 8—Contact Investigations for Tuberculosis 

40

Table 8.4 

Examples of Open-Ended Questions for TB Case Interviews 

 What symptoms do you have?

 When did your symptoms begin?

 How long have you had these symptoms?

 When did you first go to a healthcare provider about your symptoms?

 What medications do you take for your illness?

 Where do you sleep each night?

 Who else sleeps there?

 Where else do you sleep?

 Who visits your home?

 What is your daily routine?

 How do you get to work or school?

 Who rides with you to work or school?

 What is the room like where you spend most of your time at work or school?

 Who are the persons you spend time with at work, school, church, etc.?

 Who are the persons you see every day?

 What do you do in your free time?

 Where did you go on vacation?

 
Module 8—Contact Investigations for Tuberculosis 

41

 

Figure 8.4 Sample TB interview checklist. Adapted from TB Interviewing for Contact 

Investigation: A Practical Resource for the Healthcare Worker from the Global 

Tuberculosis Institute at Rutgers, the State University of New Jersey.
Module 8—Contact Investigations for Tuberculosis 

42

How Should Information Obtained from the Interview be Compiled? 

During or immediately after the interview, the investigator should take notes to keep 

track of the information being discussed. Sometimes a contact investigation form can 

help investigators compile the information obtained from the interview. Ideally, 

investigators should complete the form after the interview since it may be a distraction 

during the interview and make it more difficult to develop rapport. Whatever the 

approach, key findings from the interview must be recorded in the public health 

record.

During or immediately after the interview, the investigator should 

take notes to keep track of the information being discussed. 

Forms used for contact investigations vary from jurisdiction to jurisdiction. Some 

jurisdictions might use a standard form but have additional documents that can be 

incorporated based on the situation. For example, if the contact investigation involves 

a case who is homeless, some jurisdictions may have additional forms that may be 

incorporated to record key information relevant to homeless shelters.

Interview Special Circumstances 

Interviews Involving Minors 

The age when adolescents can be interviewed without the presence or consent of 

parents or guardians is the same as the legal age of consent in most jurisdictions and 

most circumstances. Before interviewing minors, the investigator should be familiar 

with jurisdictional policy and legal code. The presence or consent from a parent or 

legal guardian may be required.

 

Interview Not Possible 

In some instances, it is not possible to interview the case. The case could be deceased, 

difficult to locate, or medically or psychologically unable to participate in interviews. A 

contact investigation must still be done even if it is not possible to interview the case.

A contact investigation must still be done even if it is not possible to 

interview the case. 
Module 8—Contact Investigations for Tuberculosis 

43

In these situations, information on where and with whom the case spent time might be 

obtained from

 The case’s medical records 

 Databases such as public health records and local correctional facility systems

 Comparison of genotypes with other cases

 Proxy interviews 

 Location-based contact investigations

The case’s medical, public health, and correctional facility records should be carefully 

reviewed to see if there is any information to help identify contacts. The case’s TB 

genotype information, when available, should also be compared with other recent 

cases to discover potential connections to other cases. 

Additionally, proxy interviews can be used to elicit information. Proxy interviews are 

interviews conducted with persons familiar with the case’s practices, habits, and 

behaviors. Proxies may include family members, close friends, or other persons who 

know the case well. 

Proxy interviews are interviews conducted with persons familiar with 

the case’s practices, habits, and behaviors. 

A location-based approach to contact investigations is where potential TB contacts are 

found and offered TB assessments onsite, if possible. This can be useful if places 

where the case spent time while infectious are known. For more information on 

location-based approach, please refer to page 54 of this module.
Module 8—Contact Investigations for Tuberculosis 

44

Study Questions 8.8-8.10 

8.8 What is the main goal of the TB case interview? 

 

 

 

 

 

 

 

8.9 List three strategies for conducting effective interviews. 

 

 

 

 

 

 

 

 

8.10 What is a proxy interview? Who may serve as an appropriate proxy? 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

45

Case Study 8.3 

You are the public health worker assigned to conduct a contact investigation for 

Judith, a 73-year-old woman who was recently diagnosed with infectious TB 

disease. Judith lives with her daughter in a small house outside of town. You are 

conducting the case interview in her home. 

What questions should you ask Judith during the interview to learn more about 

her contacts? 

Answers to case studies are on pages 106-112
Module 8—Contact Investigations for Tuberculosis 

46

Step 4: Review Information and Develop a Plan for the Investigation 

After the investigator has interviewed the case, he or she should meet with his or her 

supervisor or the contact investigation team to review all of the information obtained 

thus far and develop a plan on how to proceed. The planning process can be done 

during a case conference. To develop a plan, the investigator or team should do the 

following activities: 

 Refine the infectious period and degree of infectiousness for the case as 

necessary

 Prioritize contacts for assessment 

 Prioritize places to conduct field visits

After the investigator has interviewed the case, he or she should 

meet with his or her supervisor or the contact investigation team to 

review all of the information obtained thus far and develop a plan on 

how to proceed. 

All of these above activities are discussed in more detail in the next few steps (steps 5–

7) of the systematic approach to contact investigation (pages 47-56) of this module).

As part of the planning process, the investigator or investigation team should also

 Establish a communication plan among staff and others involved in the 

investigation

 Clarify any jurisdictional issues 

 Establish timeframes and methods for investigation activities, data collection, 

and management

 Determine stakeholders

 Determine potential media interest

 Establish a schedule for case conferences or meetings to review challenges and 

progress

The investigation plan should be written and include where to conduct field visits, 

which contacts are currently considered a priority for assessment, and a timeline for 

accomplishing these tasks. Having a plan will help ensure that the goals and objectives 

of the contact investigation are met, and resources are used as efficiently and 

effectively as possible. Additionally, if the health department has multiple TB cases 

requiring contact investigations, the above information should be used to help 

prioritize which contact investigations require immediate attention and resources. The 
Module 8—Contact Investigations for Tuberculosis 

47

plan should be considered a work in progress with changes to be made as needed 

throughout the investigation.

The investigation plan should be written and include where to 

conduct field visits, which contacts are currently considered a priority 

for assessment, and a timeline for accomplishing these tasks. 

During case conferences about the contact investigation, investigators should note any 

similarities and potential connections to other recent TB cases in the area (e.g., 

homelessness, substance use). If cases have a characteristic in common, further 

investigation should be done to see if the cases are connected. This is because TB 

outbreaks generally involve persons with similar demographic characteristics and TB 

risk factors. (For more information, refer to Module 9, Tuberculosis Outbreak Detection 

and Response.)

Step 5: Refine the Infectious Period and Degree of Infectiousness 

At the planning meeting, the investigator should use the information from the initial 

interview to determine if the estimates of the infectious period and the degree of 

infectiousness need to be refined. 

At the planning meeting, the investigator should use the information 

from the initial interview to determine if the estimates of the 

infectious period and the degree of infectiousness need to be refined. 

For example, the initial estimate of the infectious period for the case described in 

Figure 8.1 (page 27) was August 1st to December 1st, based on information collected 

in the pre-interview phase. If the interview revealed that the case’s symptoms actually 

started September 1st, instead of November 1st, the infectious period would need to 

be revised. Rather than beginning on August 1st, the infectious period should begin on 

June 1st (3 months before symptoms began). Figure 8.5 shows the refined infectious 

period for the case presented in Figure 8.1.

Additionally, from the initial interview it may become known that the case participated 

in certain activities that may influence the degree of infectiousness. For example, 

during the interview the investigator may find out that the case sang in a choir during 

their infectious period. Since singing is considered an action that increases 

infectiousness, the initial estimate for the degree of infectiousness would need to be 
Module 8—Contact Investigations for Tuberculosis 

48

refined. The increased degree of infectiousness estimate will have implications for the

prioritization of the contact investigation, as well as for the prioritization of contacts 

needing assessment.

 

Figure 8.5 Example of refining the infectious period.

Step 6: Prioritize Contacts 

At the planning meeting, the investigator should use information from the initial 

interview to prioritize contacts for assessment. 

The priority assigned to each contact should be based on the following:

 Likelihood of transmission from the case 

 Contact’s risk for development of TB disease

The priority assigned to each contact should be based on the 

likelihood of transmission from the case and the contact’s risk for 

development of TB disease.

Some jurisdictions have tools to assist with assigning priority to contacts. Such tools 

should take both factors into account. 
Module 8—Contact Investigations for Tuberculosis 

49

The terms “close” and “casual” have been used in some public health programs to 

describe the degree of exposure contacts had to an infectious TB case. However, these 

terms do not always distinguish between contacts who require immediate assessment 

because of their higher risk of developing TB disease with those who may be at a low 

risk.

Priority should be given to locating and assessing contacts who

 Are exhibiting symptoms of TB disease

 Are at risk for rapid development of TB disease (e.g., contacts younger than 5 

years of age and contacts with weakened immune systems)

 Had repeated or extended exposure to the case 

 Were exposed in an environment where transmission was likely, such as a small, 

crowded, or poorly ventilated room or vehicle

 Were exposed during medical procedures that can release substantial numbers 

of M. tuberculosis into the air (e.g., bronchoscopy)

The highest priority should be given to locating and assessing contacts reported by the 

case as having symptoms of TB disease. A contact with symptoms could have 

undiagnosed TB disease and be transmitting M. tuberculosis to others. 

The highest priority should be given to locating and assessing 

contacts reported by the case as having symptoms of TB disease. 

Decisions about the priority level assigned to contacts should be made in consultation 

with supervisory clinical and management staff or during a case conference with the 

contact investigation team. The priority level assigned to contacts can change over 

time as new information becomes available. Thus, contacts’ priority assessment should 

be reviewed at least weekly, and updated as necessary based on the results of the 

investigation. 

Decisions about the priority level assigned to contacts should be 

made in consultation with supervisory clinical and management staff 

or during a case conference with the contact investigation team. 

For more detailed information about assigning priority to contacts, refer to the CDC’s 

Guidelines for the Investigation of Contacts of Persons with Infectious Tuberculosis, 

available from the CDC website (www.cdc.gov/tb).
Module 8—Contact Investigations for Tuberculosis 

50

Study Questions 8.11-8.12 

8.11 What two factors should be taken into account when determining the 

priority of each contact? 

 

 

 

 

 

 

 

 

8.12 In general, which contacts should be considered priority? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

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Case Study 8.4 

Derrick is a 47-year-old man who has had a severe cough for about two months 

and started treatment for TB disease three days ago. He lives alone in a small 

apartment and works the night shift three times a week with two other 

employees at the convenience store a few blocks away from his home. During the 

day, Derrick goes to friends’ apartments nearby or stays in his apartment to 

watch TV. He often goes to the local bar in his neighborhood with his friends 

Reggie and Melvin. He usually eats at one of two restaurants—the Main Street 

Diner or Susie’s Kitchen. 

Derrick says that his girlfriend, Tonya, spends the night with him a few times a 

week, and often brings her 2 year-old son, Luke. Derrick also mentions another 

girlfriend, Kelly, who has stayed over about 10 times in the past three months. 

Last month, Derrick spent several days at Kelly’s house, where she lives with her 

mother. 

 

 Based on this information, who are Derrick’s contacts? 

 

 

 

 

 

 

 Which contacts are at higher risk for TB infection and TB disease? 

 

 

 

 

 

 

Answers to case studies are on pages 106-112

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

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Case Study 8.5 

One week ago, Hector came to the health department complaining of night sweats, 

weight loss, and a cough that has lasted about a month. His sputum smears were 

positive and he started a four-drug regimen for TB disease. 

When you interviewed Hector, you found out he lives with his 32-year-old wife, 

Mimi; his two sons, Luis, 2, and Javier, 4; and his mother-in-law, Alma, 65. Hector’s 

cousin, Henry, has stopped by the house a few times in the past month. 

Hector rides to work 5 days a week in a car with his friend Joe. The ride lasts about 

30 minutes.

 

Hector works in a mail order packing warehouse. About 100 employees work in the 

main room with Hector, but the room is divided into several sections. There are 20 

persons in Hector’s section, and four of these persons are assigned to work closely 

with Hector. Hector eats lunch outside every day with these four coworkers.

 

About twice a week and on weekends, Hector goes to a small neighborhood bar 

located in the basement of a building. At the bar, Hector spends most of the time 

talking to the bartender. He notes that the bartender has been coughing a lot lately.

 

 Based on this information, who are Hector’s contacts? 

 

 

 

 

 Which contacts should be considered a priority? 

 

 

 

 

Answers to case studies are on pages 106-112

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

53

Step 7: Conduct Field Visits 

A field visit, also sometimes called a site visit, means visiting the case’s residence and 

other places where the case spent time while infectious. Field visits are an essential 

component of a TB contact investigation as they allow the investigator to view and 

assess the environment in which transmission may have occurred. 

Field visits are an essential component of a TB contact investigation 

as they allow the investigator to view and assess the environment in 

which transmission may have occurred. 

In some instances, a field visit to a residence is conducted at the same time as the 

initial interview or re-interview with the case. Additional locations to visit can be 

determined by using the list of places reported during the interview or discussed 

during the planning meeting.

Field visits serve four main functions:

1. Identify additional cases of TB disease

2. Identify additional contacts 

3. Gather additional information about environmental characteristics of places 

where exposure occurred

4. Lay a foundation for additional contact investigation activities at those locations, 

if needed

During field visits, the contact investigator should

 Maintain confidentiality of cases and contacts 

 Refer persons with symptoms of TB disease for immediate medical evaluation, 

including a chest x-ray

 Observe environmental characteristics of the site such as room size, crowding, 

ventilation, low ceilings, and dense air

 Look for evidence of contacts not present at the time of the visit, such as 

pictures or belongings of others who may visit or live at the case’s residence 

(see Figure 8.6)

 Obtain lists of clients, employees, volunteers, and visitors who were present at 

worksites during the case’s infectious period 

 Explore the possibility of offering TB assessment to contacts onsite at that 

location
Module 8—Contact Investigations for Tuberculosis 

54

The field visit can also be an opportunity to educate cases and contacts about the 

purpose of a contact investigation and the basics of TB testing and treatment. 

The use of a standardized data collection form can assist investigators in recording 

important information about each site visited. Field visit forms will vary from 

jurisdiction to jurisdiction.

 

 

Figure 8.6 The investigator is conducting a field visit. She is looking for evidence of 

other contacts.

Location-Based Approach to Contact Investigations 

In some situations, field visits will also be used as an opportunity to learn about 

potential contacts and to offer onsite TB assessments for those contacts. This is 

referred to as a location-based approach to contact investigation. If a traditional 

name-based approach does not produce an adequate list of contacts, or if the case 

does not provide information about contacts, a location-based approach to the contact 

investigation should be considered. The goal of this approach is to assess persons who 

could have been exposed at a particular location (e.g., bar, drug-usage site, or 

shelter), but may not have been named as contacts. 

The goal of a location-based approach is to assess persons who 

could have been exposed at a particular location (e.g., bar, drugusage site, or shelter), but may not have been named as contacts. 
Module 8—Contact Investigations for Tuberculosis 

55

A location-based approach can be particularly useful when

 It is not possible to interview the case, but investigators can establish places 

where the case spent time during the infectious period

 A case does not or cannot provide the name or the location of their contacts

 Shelters or other social service agencies are unable to provide a list of contacts

During location-based assessments, investigators should actively seek out information 

that could help identify priority contacts. 

 

Field Visit Safety 

Personal Safety for the Contact Investigator 

Contact investigators who conduct field visits should follow health department policies 

and local law enforcement recommendations regarding personal safety. Current 

information about local high-risk areas for crime can be useful in planning and 

conducting safe field visits. 

Contact investigators who conduct field visits should follow health 

department policies and local law enforcement recommendations 

regarding personal safety. 

General safety precautions recommended for contact investigators include

 Wearing an identification badge with a current photograph

 Working in pairs when visiting isolated or dangerous areas

 Having a working cell phone

 Limiting visibility of valuable items

 Informing a coworker or supervisor of itinerary, planned route, and expected 

time of return

Infection Control Precautions 

Contact investigators should follow infection control precautions while visiting or 

interviewing a potentially infectious TB case at any location, including the home. 

Contact investigators should follow infection control precautions 

while visiting or interviewing a potentially infectious TB case at any 

location, including the home. 
Module 8—Contact Investigations for Tuberculosis 

56

If the visit or interview takes place in an airborne infection isolation (AII) room, the 

investigator should wear an N95 respirator for which they have been fit-tested. 

If a case is discharged home while still infectious, the investigator should wear an N95 

respirator and the case should be asked to wear a surgical mask. The investigator may 

also choose to do the interview outdoors. However, because the sight of respirators or 

masks might add to the social stigma of TB, investigators should be careful about 

using them where others may notice. For more information about infection control 

precautions for TB, refer to Module 5, Infectiousness and Infection Control.
Module 8—Contact Investigations for Tuberculosis 

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Study Questions 8.13-8.14 

8.13 What are the four main functions of a field visit? 

 

 

 

 

 

 

 

 

 

 

8.14 List four safety precautions investigators should take while conducting 

field visits. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

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Case Study 8.6 

Carmen is a 30-year-old woman who was recently diagnosed with infectious TB 

disease. She works at the local community college and lives with her aunt.

A contact investigator from the local health department is conducting an 

interview with Carmen at Carmen’s home. Three coworkers and her aunt have 

been reported to be contacts by Carmen.

 

 Refer back to Figure 8.6 on page 54. Based on what is visible in the photo, 

is there evidence of any additional contacts in Carmen’s home other than 

her aunt? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to case studies are on pages 106-112

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

59

Step 8: Conduct Contact Assessments 

Contact investigators should meet and assess priority contacts within three working 

days of the contact being identified. 

Contact investigators should meet and assess priority contacts within 

three working days of the contact being identified. 

When meeting with the contacts, the investigator should ensure that confidentiality is 

maintained by not revealing any personally identifying information about the case or 

any specific details about their exposure.

The major activities of the contact assessment include

 Meeting with the contact

o Maintaining confidentiality

o Collecting and confirming information

 Conducting a medical evaluation

o Medical history

o HIV test 

o TB symptom review

o TST or IGRA to test for infection with M. tuberculosis

For more detailed information on contact assessment activities, refer to the 

Assessment and Management of TB Contacts section of this module, page 69.

Step 9: Determine Whether to Expand or Conclude an Investigation

As part of the contact investigation process, it is important to continually review 

findings to determine if there is a need to expand investigation efforts beyond the 

priority contacts. Expanding the investigation includes assessing contacts who were 

not originally considered a priority or finding new contacts in need of TB assessment. 

Expanding the investigation includes assessing contacts who were 

not originally considered a priority or finding new contacts in need of 

TB assessment. 

 
Module 8—Contact Investigations for Tuberculosis 

60

Evidence of Recent Transmission 

The need for expansion is generally determined by evidence of recent transmission. 

Evidence of recent transmission further confirms that a case was infectious and, thus, 

implies an increased likelihood that others were infected.

Evidence of recent transmission includes

 TB infection or TB disease in contacts younger than 5 years of age

 Change in contacts’ TST or IGRA status from negative to positive 

 A greater-than-expected rate of TB disease or TB infection among priority 

contacts 

 Evidence of secondary transmission

 TB disease among contacts not initially considered priority (particularly if 

genotypes match that of the case)

The need for expansion is generally determined by evidence of recent 

transmission. 

TB Infection or TB Disease in Contacts Younger than 5 years of Age 

When children younger than 5 years of age have LTBI or TB disease, there is reason to 

suspect recent transmission.

When children younger than 5 years of age have LTBI or TB disease, 

there is reason to suspect recent transmission. 

Change in Contacts’ TST or IGRA Status from Negative to Positive 

As part of a contact assessment, contacts should receive a TST or IGRA to determine if 

they are infected with M. tuberculosis. Contacts with an initial negative TST or IGRA 

result should be retested 8 to 10 weeks after their last exposure to the case. If the 

result of the repeat test is positive, this implies that recent transmission may have 

occurred. (For more information on using TST or IGRA during contact assessments, 

refer to page 69.)

A Greater-than-Expected Rate of TB Disease or TB Infection among Priority Contacts 

Greater-than-Expected Rate of TB Disease 

During a contact investigation it is not unusual to find one case of TB among priority 

contacts. An infected contact who develops TB disease is referred to as a secondary 
Module 8—Contact Investigations for Tuberculosis 

61

case of TB. It is important to remember that for each secondary case of TB, a separate 

contact investigation needs to be considered immediately.

It is important to remember that for each secondary case of TB, a 

separate contact investigation needs to be considered immediately. 

More than one secondary case suggests the contact investigation may need to be 

expanded to other contacts. It can also mean an outbreak is occurring, particularly if 

genotypes match, because matching genotypes help confirm transmission links. Also, 

if an additional case in the same geographic area around the same time has a matching 

genotype, and neither case identified the other as a contact, contact investigators 

should determine if there were any missed connections between these two cases.

 

Greater-than-Expected Prevalence of TB Infection 

A greater-than-expected prevalence of TB infection among contacts can also be 

evidence of recent transmission. The prevalence of TB infection is the percentage of 

persons infected with M. tuberculosis within a defined population.

To determine if the prevalence of infection among contacts is higher than expected, it 

is necessary to know the background prevalence of TB infection ideally among a local 

population similar to that of the contacts being evaluated (e.g., immigrants from 

Mexico). In the absence of information on a specific local population similar to the 

contacts being evaluated, the prevalence in the general population within the local area 

can be used. However, the latter prevalence will not be a good estimate if the contacts 

being evaluated are substantially different from the general population in terms of 

possible prior exposure to TB. If the prevalence of TB infection among contacts is 

higher than the background prevalence, this could indicate recent transmission and a 

need to expand the contact investigation.

The prevalence of TB infection among contacts can be calculated by the following 

steps:

1. Determine the total number of contacts who have completed testing (TST or 

IGRA). Do not include contacts who have a documented previous positive test 

result, have not completed testing, or who were not tested.

2. Determine the number of contacts with a newly positive TST or IGRA result.
Module 8—Contact Investigations for Tuberculosis 

62

3. Divide the number of contacts with a newly positive test result by the total 

number of contacts that have completed testing (i.e., divide the number from 

Step 2 by the number from Step 1)

4. Multiply the number from Step 3 by 100%. The resulting number is the TB 

infection prevalence for that group of contacts.

An example of how to determine the prevalence of newly diagnosed infection with M. 

tuberculosis among contacts is shown in Figure 8.7.

Evidence of Secondary Transmission 

If the contact investigation for the secondary case finds additional persons with LTBI or 

TB disease, this is referred to as secondary transmission. Secondary transmission is 

strong evidence of a potential outbreak occurring, particularly if genotypes match. 

More information about detecting TB outbreaks is presented in Module 9, Tuberculosis 

Outbreak Detection and Response.

Secondary transmission is strong evidence of a potential outbreak 

occurring, particularly if genotypes match. 
Module 8—Contact Investigations for Tuberculosis 

63

 

Figure 8.7 Calculation of TB infection prevalence for a group of contacts.

 

TB Disease among Contacts Not Considered Priority 

If a contact who was originally considered a low priority for assessment is found to 

have TB disease, this may indicate a need to expand the investigation to other low 

priority contacts. 

Generally, if any of the above evidence of recent transmission is found, expanding the 

contact investigation to include contacts at a lower priority should be considered. This 

may also indicate a need to re-interview the case to identify other contacts. If there is a 

plan to expand the investigation, the TB program still needs to continue to ensure that 

all priority contacts are properly assessed, managed, and treated. If this is a challenge, 

consultation and assistance from the next higher level of public health administration 

Example Calculation of TB Infection Prevalence for a Group of Contacts 

Eleven contacts were identified for a reported TB case. One contact had a documented 

previous positive TST result. The other 10 contacts did not have documented previous 

TST results. These 10 contacts had a skin test administered; seven had positive TST 

results and three had negative TST results. 

Step 1: Determine the total number of contacts who completed testing for M. tuberculosis 

 infection. Do not include contacts who have a documented previous positive test 

 result, have not completed testing, or who were not tested. 

10 contacts completed testing. 

Step 2: Determine the number of contacts with a newly positive TST result. 

7 of the 10 contacts who were tested had a positive TST result. 

Step 3: Divide the number of contacts with a newly positive test result by the total number 

of contacts that completed testing. 

7/10 = 0.70 

Step 4: Multiply the number from Step 3 by 100%. 

0.70 x 100% = 70% 

Answer: The TB infection prevalence for the contacts is 70%. 

 
Module 8—Contact Investigations for Tuberculosis 

64

should be sought (e.g., the county health department would consult with the state 

health department). 

If there is a plan to expand the investigation, the TB program still needs to 

continue to ensure that all priority contacts are properly assessed, managed, 

and treated. 

It is important to note that evidence of recent transmission may indicate an outbreak is 

occurring. If an outbreak is suspected, supervisory staff should immediately be alerted. 

More information about detecting TB outbreaks is presented in Module 9, Tuberculosis 

Outbreak Detection and Response.

If an outbreak is suspected, supervisory staff should immediately be alerted. 

Concluding a Contact Investigation 

If no evidence of recent transmission is found, the investigation usually would not be 

expanded. 

If no evidence of recent transmission is found, the investigation usually would 

not be expanded. 

A contact investigation can be concluded if

 All contacts have been assessed for TB infection and disease

 Contacts with LTBI have completed or are close to completing treatment

 No additional secondary cases of TB are found, either among identified contacts 

or through reviewing genotype information

Once the contact investigation is concluded, all investigation activities should be 

evaluated.
Module 8—Contact Investigations for Tuberculosis 

65

Study Questions 8.15-8.16 

8.15 List five indicators of recent transmission. 

 

 

 

 

 

 

 

 

 

 

8.16 When can a contact investigation be concluded? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

66

Step 10: Evaluate the Contact Investigation Activities 

An evaluation of the investigation activities should be conducted with or by a 

supervisor. The purpose of evaluating the activities of the investigation is to determine

 If the appropriate contacts were identified

 How many contacts were diagnosed with LTBI

 How many contacts with LTBI completed treatment 

 How many additional cases of TB disease were found 

 How many secondary cases of TB disease completed treatment

 How many contacts were not located

 How many contacts were located, but did not complete assessment 

 The timeliness of identifying and assessing contacts, and starting treatment if 

necessary

 If the contact investigation was performed in all necessary settings

 If the contact investigation was expanded appropriately

The answers to these questions will help determine how effectively and efficiently the 

contact investigation activities were conducted. 

An evaluation of the investigation activities should be conducted with 

or by a supervisor. 

Evaluation of activities should be conducted during case reviews and contact 

investigation team meetings throughout the contact investigation process. This will 

allow for any necessary immediate changes to improve the outcomes of the 

investigation.

At the end of the investigation, an evaluation can help identify areas in need of 

improvement. Additionally, many public health programs use a cohort review process. 

This allows for an opportunity to evaluate the contact investigation activities for each 

case within a certain time frame and identifies areas in need of improvement. Several 

resources are available about the TB cohort review process, including Understanding 

the TB Cohort Review Process: Instruction Guide and DVD Package. This resource is 

available from the CDC website.
Module 8—Contact Investigations for Tuberculosis 

67

The cohort review process provides an opportunity to evaluate the 

contact investigation activities for each case within a certain time 

frame and identifies areas in need of improvement. 

Contact investigations are also an important indicator of the overall effectiveness of a 

TB control program. Thus, on a programmatic level, an aggregate of all contact 

investigation activities should be compiled and analyzed using data from the National 

Tuberculosis Indicators Project (NTIP).

Evaluation of program performance ensures that resources are being used effectively 

and for the highest priority activities. Conducting contact investigations is a priority 

activity. Information from each contact investigation should be compiled separately 

and examined by management staff as part of ongoing part of program evaluation 

activities. 

The results of these program evaluations can be used to

 Determine program effectiveness

 Identify program strengths and areas in need of improvement

 Determine training needs

 Prioritize program activities and resources

In order to evaluate the contact investigation activities and overall program 

effectiveness, there should be a system in place to keep track of the number of 

contacts 

 Identified

 Assessed and yet-to-be assessed

 Diagnosed with LTBI or TB disease

 Started on treatment for LTBI or TB disease

 Who have completed treatment
Module 8—Contact Investigations for Tuberculosis 

68

Study Questions 8.17-8.18 

8.17 What is the purpose of evaluating the TB contact investigation? 

 

 

 

 

 

 

 

 

 

8.18 List the 10 steps of the systematic approach to contact investigation. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

69

Assessment and Management of TB 

Contacts 

This section provides more detailed information about Step 8 of the Systematic 

Approach to Contact Investigations. 

A contact assessment involves examining the contact for LTBI or TB disease. Health 

departments should have policies and procedures in place for the assessment and 

management of TB contacts. If a contact refuses to respond to requests for 

assessment, some states have communicable disease regulations or laws that set the 

precedents for legal action. 

Health departments should have policies and procedures in place for 

the assessment and management of TB contacts. 

What is Included in a Contact Assessment? 

The major activities of the contact assessment include 

 Meeting with the contact 

o Collecting and confirming information 

o Maintaining confidentiality 

 Conducting a medical evaluation 

o Medical history 

o HIV test 

o TB symptom review 

o TST or IGRA to test for infection with M. tuberculosis

Meeting with Contacts 

Investigators should meet in person and assess priority contacts within three working 

days of the contact being identified. When meeting with contacts, investigators should 

introduce themselves and explain that the purpose of the visit is to discuss a health 

matter. Before discussing any specific information, the investigator should verify the 

contact’s identity. The discussion should be continued at a place that allows for 

privacy. 
Module 8—Contact Investigations for Tuberculosis 

70

Investigators should meet in person and assess priority contacts 

within three working days of the contact being identified. 

The investigators should inform the contact that he or she may have been exposed to 

TB and will need to be medically evaluated for TB disease or LTBI. The investigators 

should explain TB disease and how it is transmitted, diagnosed, and treated. TB 

educational tools can be used to help answer any questions the contact may have 

about TB disease or LTBI.

 

Collecting and Confirming Information 

Contacts generally do not need to undergo the same in-depth interviewing process as 

TB cases. Contacts should be asked if they have any signs and symptoms of TB 

disease; or if they have a history of TB disease or LTBI, whether they completed 

treatment for either. It may be useful to ask the contact a few questions to confirm 

where they spent time and if they have any acquaintances who have signs and 

symptoms of TB. These questions may provide information about additional contacts 

and places the case had not mentioned.

Contacts should be asked if they have any signs and symptoms of TB 

disease; or if they have a history of TB disease or LTBI, whether they 

completed treatment for either. 

Maintaining Confidentiality 

When meeting with contacts, the investigator should ensure that confidentiality is 

maintained by not revealing any personally identifying information about the case or 

any specific details about the exposure. Additionally, the investigator should be careful 

not to accidentally reveal clues about the case. Confidentiality should not be violated 

even if contacts refuse to be evaluated. 

When meeting with contacts, the investigator should ensure that 

confidentiality is maintained by not revealing any personally 

identifying information about the case or any specific details about 

the exposure. 

The following strategies can be used to protect confidentiality when meeting with 

contacts:
Module 8—Contact Investigations for Tuberculosis 

71

 Use gender-neutral language. For example, “Somebody was diagnosed with TB 

and they were concerned about you” instead of “A woman was diagnosed with 

TB and she was concerned about you.”

 Do not mention the case’s healthcare worker, place and dates of diagnosis, or 

hospitalization. 

 Do not mention the environment in which the exposure occurred. For example, 

“You have been around somebody who has TB” instead of “You have been 

around somebody at work who has TB.”

 Do not confirm the name of the case if the contact correctly guesses his or her 

identity.

The investigator should also let the contact know that any information provided will 

remain confidential.

 

Conducting a Medical Evaluation 

The contact’s medical evaluation may occur in the field or at the clinic. The following 

are components of a medical evaluation for contacts:

 Medical and social history

 HIV test

 TB symptom review

 TST or IGRA

Medical and Social History 

The medical history of the contact should include information about prior LTBI or TB 

diagnosis, treatment, or exposure, and medical or social risk factors for progression to 

TB disease. 

 

HIV Test 

Contacts should be offered an HIV test if their status is unknown, even if the person is 

at low risk for HIV. 

TB Symptom Review 

All contacts should be assessed for symptoms of TB disease. General symptoms of TB 

disease include 

 Fever 
Module 8—Contact Investigations for Tuberculosis 

72

 Chills 

 Night sweats 

 Weight loss 

 Appetite loss 

 Fatigue 

 Malaise 

Symptoms of pulmonary TB disease include 

 Cough lasting 3 weeks or longer 

 Chest pain 

 Coughing up blood or sputum (phlegm) 

Symptoms of extrapulmonary TB disease depend on the part of the body that is 

affected. For example 

 TB disease in spine may cause back pain 

 TB disease in kidneys may cause blood in urine 

 TB disease in lymph nodes may cause swelling in the neck

 TB disease of the larynx may cause hoarseness

Contacts with symptoms of TB disease should be further evaluated with a chest x-ray 

and three respiratory specimens for AFB smear and culture. For more information on 

diagnosing TB disease, please refer to Module 3, Targeted Testing and the Diagnosis 

of Latent Tuberculosis Infection and Tuberculosis Disease.

Contacts with symptoms of TB disease should be further evaluated 

with a chest x-ray and three respiratory specimens for AFB smear 

and culture. 

TST or IGRA 

Contacts should be tested for M. tuberculosis infection using either a TST or an IGRA. 

Contacts who have a history of TB disease or a previous positive TST or IGRA result 

generally do not need to be retested for M. tuberculosis infection. They should be 

assessed for signs and symptoms of TB disease and asked about prior treatment for 

LTBI or TB disease. 
Module 8—Contact Investigations for Tuberculosis 

73

Contacts should be tested for M. tuberculosis infection using either a 

TST or an IGRA. 

For those contacts given a TST or tested with an IGRA, a repeat test may be needed 

depending on the result of the test. The same method of testing for infection should 

be used for both the initial and repeat test (i.e., if the first test was a TST, the repeat 

test should be a TST). For more information on administering and interpreting TST or 

IGRA results, refer to Module 3, Targeted Testing and the Diagnosis of Latent 

Tuberculosis Infection and Tuberculosis Disease.

Initial Negative TST or IGRA 

If the initial TST or IGRA is negative, a repeat test is needed if the initial test was given 

less than 8 to 10 weeks since the contact’s last exposure to the case. This is because it 

can take 2 to 8 weeks after being infected with M. tuberculosis for the body’s immune 

system to mount a response detectable by the tests. The time between the contact’s 

last exposure to the case and when a TST or IGRA can reliably detect infection is 

referred to as the window period.

If the initial TST or IGRA is negative, a repeat test is needed if the 

initial test was given less than 8 to 10 weeks since the contact’s last 

exposure to the case. 

The time between the contact’s last exposure to the case and when a 

TST or IGRA can reliably detect infection is referred to as the window 

period. 

The repeat test should be conducted 8 to 10 weeks after the last exposure to the case. 

If the result of the repeat test is positive, and TB disease is ruled out, the contact 

should be classified as recently infected and followed-up and treated appropriately. 

Figure 8.8 shows an example of calculating the window period and determining when a 

repeat test should occur for contacts with an initial negative test result. 

 

 
Module 8—Contact Investigations for Tuberculosis 

74

Initial Positive TST or IGRA 

If the initial TST or IGRA is positive, the contact should be considered positive for M. 

tuberculosis infection and a repeat test is unnecessary, even if it has been less than 8 

weeks since the last exposure to the case. A TST result of 5 mm or more is considered 

a positive result for a TB contact. The interpretation of IGRA results is the same for all 

patients; no cut-points are defined differently for contacts. TB disease should first be 

ruled out before initiating LTBI treatment.

If the initial TST or IGRA is positive, the contact should be considered 

positive for M. tuberculosis infection and a repeat test is 

unnecessary, even if it has been less than 8 weeks since the last 

exposure to the case. 

 

Figure 8.8 Example of calculating the window period. If a contact’s last exposure to a 

TB case was July 1st, and he or she had a negative TST or IGRA on August 1st, a 

second TST or IGRA should be done between September 1st and September 15th (8 to 

10 weeks after July 1st).

Management and Treatment of Contacts 

For a contact investigation to be considered successful, contacts who have TB disease 

or LTBI should complete treatment. The appropriate management and treatment of 

these contacts is the responsibility of the health department.
Module 8—Contact Investigations for Tuberculosis 

75

Management and Treatment of Contacts with TB Disease 

Contacts who have TB disease should be managed and treated in accordance with CDC 

treatment guidelines. DOT and the use of incentives and enablers are recommended to 

support adherence and achieve completion of treatment. For more information about 

the treatment of TB disease, refer to Module 4, Treatment of Tuberculosis Infection 

and Tuberculosis Disease. For detailed recommendations for the treatment of TB 

disease, refer to the Official American Thoracic Society/Centers for Disease Control 

and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: 

Treatment of Drug-Susceptible Tuberculosis. It is important to remember that for each 

contact who is found to have infectious TB disease, a separate contact investigation 

needs to be started immediately.

Contacts who have TB disease should be managed and treated in 

accordance with CDC treatment guidelines. 

Management and Treatment of Contacts with LTBI 

Once TB disease has been ruled out, treatment for LTBI should be offered to all 

contacts with a positive TST or IGRA, unless there is a compelling reason not to do so. 

Treatment should be offered regardless of whether the contact has received the BCG 

vaccine in the past. Treatment should also be offered to contacts with a prior positive 

TST or IGRA who did not complete treatment for LTBI.

Once TB disease has been ruled out, treatment for LTBI should be 

offered to all contacts with a positive TST or IGRA, unless there is a 

compelling reason not to do so. 

In general, contacts with a positive TST or IGRA and a documented history of LTBI 

treatment completion do not need to be re-treated. However, in some circumstances, 

repeat treatment for LTBI may be advisable based on the contact’s risk for re-infection 

with M. tuberculosis and progression to TB disease. 

Special Considerations in TB Contact Assessment and Management 

Window Period Prophylaxis 

Contacts Younger than 5 Years of Age 

Because of their age, young children with M. tuberculosis infection are known to have 

been recently infected, and thus are at a high risk of progressing to TB disease. Young 
Module 8—Contact Investigations for Tuberculosis 

76

children are also more likely than older children and adults to develop life-threatening 

forms of TB disease, especially meningeal and disseminated disease. 

Children younger than 5 years of age should be medically assessed, including a chest 

x-ray, regardless of a history of LTBI or TB disease treatment or an initial negative TST 

or IGRA result. Since TB disease may present differently in children than adults, 

clinicians with pediatric TB disease experience should be consulted during the 

assessment and medical evaluation process.

Once TB disease has been ruled out, children younger than 5 years of age should 

receive LTBI treatment, even if their initial TST or IGRA result is negative. This is called 

window period prophylaxis.

Once TB disease has been ruled out, children younger than 5 years of 

age should receive LTBI treatment, even if their initial TST or IGRA 

result is negative. This is called window period prophylaxis. 

Window period prophylaxis can be stopped if ALL of the following conditions are met: 

 The child is at least 6 months of age

 The second TST or IGRA is negative

 The second TST or IGRA was done at least 8 weeks after the child was last 

exposed to an adult with infectious TB disease

If the second TST or IGRA is positive, a full course of LTBI treatment should be 

continued and completed.

 

Contacts with HIV Infection 

Because of their weakened immune systems, persons living with HIV are at high risk 

for rapidly developing TB disease. Contacts known or suspected to be HIV-infected 

should be medically evaluated, including a chest x-ray, to rule out TB disease. Expert 

consultation should be sought for contacts with HIV infection who need TB treatment.

Once TB disease has been ruled out, HIV-infected contacts should receive window 

period prophylaxis for LTBI regardless of their initial IGRA or TST result. In general, 

treatment of LTBI should be continued even if the second TST or IGRA result is 

negative. This is because some HIV-infected contacts may not be able to produce a 
Module 8—Contact Investigations for Tuberculosis 

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positive TST or IGRA result because of their weakened immune systems. Clinicians 

should use TB exposure information (e.g., frequency, duration, and infectiousness of 

the case) to guide their decision on whether to continue or discontinue LTBI treatment. 

Once TB disease has been ruled out, HIV-infected contacts should 

receive window period prophylaxis for LTBI regardless of their initial 

IGRA or TST result. 

Contacts with Other Immune Impairment 

Expert consultation should be sought to determine if contacts with immune 

impairments other than HIV infection (e.g., contacts taking immunosuppressive 

therapies) could benefit from window period prophylaxis, regardless of their initial TST 

or IGRA results. Offering treatment for presumed M. tuberculosis infection may be 

considered if the likelihood of infection is high, based on the circumstances of the 

exposure and prevalence of TB infection among other contacts.

Table 8.5 summarizes the CDC recommendations for the prophylactic treatment of 

presumed infection with M. tuberculosis for contacts younger than 5 years of age and 

contacts with HIV infection.

 
Module 8—Contact Investigations for Tuberculosis 

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Table 8.5 

Recommendations for Prophylactic Treatment of Presumed Infection with M. 

tuberculosis for Contacts Younger than 5 Years of Age and Contacts with HIV Infection 

Contacts Less than 

6 Months of Age* 

Contacts Older than 

6 Months but 

Younger than 5 

Years of Age 

 

Contacts with HIV 

(any age) 

When to 

start 

treatment 

As soon as possible if medical assessment and chest x-rays show 

no evidence of current TB disease, even if initial TST or IGRA result 

is negative

 

When to 

stop 

treatment 

Contact reaches 6 

months of age and 

TST or IGRA done 8 

to 10 weeks after 

last exposure is 

negative

or 

Once a full course of 

treatment for LTBI is 

completed

TST or IGRA done 8 

to 10 weeks after 

last exposure is 

negative

 

or 

Once a full course of 

treatment for LTBI is 

completed

Once a full course 

of treatment for 

LTBI is completed

 

* Negative TST and IGRA results can be unreliable in children younger than 6 months 

of age.

Contacts to Drug-Resistant TB 

Treatment regimens for contacts should reflect the drug susceptibility patterns of the 

M. tuberculosis isolate of the presumed source case. Selection of treatment regimens 

for contacts to drug-resistant TB requires expert consultation. Additionally, supporting 

adherence to LTBI treatment for infected contacts of drug-resistant TB is very 

important. Consideration should be given to providing DOT and using incentives and 

enablers for contacts believed to be infected with drug-resistant M. tuberculosis. 

 
Module 8—Contact Investigations for Tuberculosis 

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Contacts of Isoniazid-Resistant TB 

If a person is a contact to isoniazid-resistant TB, a 4-month regimen of daily rifampin 

may be recommended. In situations where rifampin cannot be used, rifabutin may be 

substituted. 

 

Contacts of Multidrug-Resistant TB 

The risk for developing TB disease should be considered before recommending LTBI 

treatment for contacts to multidrug-resistant (MDR) TB. MDR-TB contacts may be 

treated for 6–12 months or they can be observed for signs and symptoms of disease 

without treatment. If treating an MDR-TB contact for LTBI, an alternative regimen of 

drugs to which the M. tuberculosis isolate is known to be susceptible should be used. 

Immunocompromised contacts should be treated for 12 months. All persons with

suspected MDR LTBI should be followed and observed for signs and symptoms of 

TB disease for 2 years, regardless of the treatment regimen. An expert in the 

treatment of MDR TB should be consulted. 

For more information about the treatment of LTBI, refer to Module 4, Treatment of 

Latent Tuberculosis Infection and Tuberculosis Disease. For detailed 

recommendations for the treatment of LTBI, refer to the CDC’s Targeted Tuberculin 

Testing and Treatment of Latent Tuberculosis Infection and Update of 

Recommendations for Use of Once-Weekly Isoniazid-Rifapentine Regimen to Treat 

Latent Mycobacterium tuberculosis Infection.

Figure 8.9 on page 81 diagrams the assessment and management process of TB 

contacts. This figure is presented as a guide only, and is not meant to substitute 

for careful consideration of each contact’s risk of infection and progression to TB 

disease.

Data Management and Collection for Contacts 

To ensure that contacts are managed and followed-up appropriately, it is essential to 

have a good data collection and management system. Data should be recorded 

throughout the contact assessment and management process. This information will 

also be used to evaluate the success of the contact investigation. 
Module 8—Contact Investigations for Tuberculosis 

80

To ensure that contacts are managed and followed-up appropriately, 

it is essential to have a good data collection and management 

system. 

Information collected from each contact may vary by jurisdiction. Each jurisdiction may 

have their own forms for collecting information about contacts and for summarizing 

investigation findings. Some health jurisdictions have a separate record for each 

contact, while others have multiple contacts recorded on a single form that is attached 

to the index case records. 

Table 8.6 lists information that should be collected about each contact. Some of this 

information will be collected from the case during the interview, and some of it will be 

collected from the contact during the investigation process.

 

 
Module 8—Contact Investigations for Tuberculosis 

81

 

Figure 8.9 Assessment and management of TB contacts.

 

 
Module 8—Contact Investigations for Tuberculosis 

82

Table 8.6 

Information to Collect About Each Contact 

Information to Obtain from the Case

 Name(s)

 Address(es) and telephone number(s)

 Gender

 Physical description

 Contact’s relationship to the case

 Date of last exposure to the case

 Location where exposure occurred

 Frequency and durations of the exposure(s)

 Physical proximity between the contact and the case during the exposure

Information to Obtain from the Contact

 Basic demographic information, including name(s), date of birth

 Preferred language

 Address(es) and telephone number(s)

Information to Obtain During the Assessment Process

 Date and location of the assessment

 Risk factors for development of TB disease

 Symptoms of TB disease, if any 

 TST or IGRA dates and results

 Chest x-ray dates and results

 HIV infection status

 Final diagnostic classification

 Treatment and other follow-up

 

 
Module 8—Contact Investigations for Tuberculosis 

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Study Questions 8.19-8.21 

8.19 What are the major activities of the contact assessment? 

 

 

 

 

 

 

 

8.20 What is the window period? 

 

 

 

 

 

 

 

 

8.21 What is window period prophylaxis? Which contacts should receive window 

period prophylaxis? 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

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Case Study 8.7 

Priya is a 34-year-old woman who was diagnosed with infectious TB disease. As part of 

her contact investigation, you identified the following priority contacts: 

 Naveen (husband, 35 years old)

 Sanjay (son, 3 years old)

 Asha (close friend, 37 years old)

 Paul (co-worker, 52 years old)

 Marie (co-worker, 43 years old) 

Five weeks have passed since the contacts were last exposed to Priya while she was 

infectious. These contacts (a total of 5) have been assessed by the contact investigation 

team. None of the contacts were found to have TB symptoms. 

The skin test results were as follows:

 Naveen: 11 mm

 Sanjay: 0 mm

 Asha: 5 mm

 Paul: 3 mm

 Marie: 0 mm 

 What follow-up testing and treatment are needed for contacts with a positive skin 

test? 

 

 

 Should any follow-up testing be given to contacts with a negative skin test? 

 

 

 Which contacts should receive a repeat skin test? When should the repeat test be 

performed? 

 

 

Answers to case studies are on pages 106-112

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

85

TB Contact Investigations in 

Congregate Settings 

This section highlights challenges and solutions to conducting TB contact 

investigations in congregate settings. Local public health programs should consult with 

the next higher level of public health administration if needed. 

What is a Congregate Setting? 

A congregate setting is a setting in which a group of persons reside in close physical 

proximity. Examples of congregate settings include 

 Schools 

 Shelters 

 Nursing homes 

 Correctional facilities 

 Workplaces 

 Hospitals or other healthcare settings 

How are Contact Investigations Conducted in Congregate Settings? 

Contact investigations involving congregate settings should follow the systematic 

contact investigation process presented on pages 20-67 of this module. However, 

there may be some additional challenges to consider when conducting an investigation 

in a congregate setting, including 

 Large numbers of contacts 

 Incomplete data for determining which contacts should be prioritized for 

assessment 

 Difficulties related to maintaining confidentiality 

 Incomplete information about contacts’ names and locating information 

 A need to collaborate with officials and administrators who are not familiar with 

TB 

 Media interest, particularly for investigations involving schools or worksites 

 Political implications of negative publicity related to TB 

 Legal implications for the facility 
Module 8—Contact Investigations for Tuberculosis 

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To effectively address these potential challenges, contact investigations involving 

congregate settings often require additional resources. This is to ensure that other 

essential TB control activities are not disrupted.

To effectively address potential challenges, contact investigations 

involving congregate settings often require additional resources to 

ensure that other essential TB control activities are not disrupted. 

An initial notification of the need for a contact investigation in the congregate setting 

can occur by phone call. This call should also be used to schedule an in-person 

meeting with administrators to discuss the contact investigation process. 

At the meeting, the following items should be discussed:

 Purpose of the meeting

 Basic TB concepts 

 Confidentiality issues 

 Infectious period 

 Total number of persons in the congregate setting 

 Process of identifying, prioritizing, and testing contacts

 Potential media interest

Because of confidentiality issues, contact investigators should be careful not to reveal 

personally identifying information to administrators without the case’s knowledge and 

without reviewing local jurisdiction policy and consultation with a supervisor at the TB 

program. In some situations, a signed confidentiality agreement from the 

administrators or consent from the case may be needed.

Whenever possible, health departments should collaborate with administrators from 

congregate settings to identify opportunities for efficient and convenient assessment 

of contacts and delivery of treatment to contacts for LTBI or TB disease. Onsite 

assessment is typically the most effective way to reach contacts. If such an approach is 

not possible, special arrangements may be necessary to ensure priority contacts are 

completely assessed. For example, health departments may need to extend clinic 

hours or hire additional staff. As a last resort, the health department can notify 

contacts in writing to seek assessment for TB with their own healthcare provider.
Module 8—Contact Investigations for Tuberculosis 

87

Whenever possible, health departments should collaborate with 

administrators from congregate settings to identify opportunities for 

efficient and convenient assessment of contacts and delivery of 

treatment to contacts for LTBI or TB disease.

Correctional Facilities 

Investigations involving correctional facilities can be particularly challenging because 

of crowded conditions, large numbers of contacts (both inmates and correctional 

employees), poor ventilation, incomplete records, inaccessible records, misconceptions 

about TB and its transmission, slow access to medical care, and high turnover or 

movement of inmates.

Identifying contacts requires that investigators collect information on where the case 

spent time, as well as any work assignments and activities within the correctional 

facility. Because of the potential intensity of exposure within a crowded or poorly 

ventilated space, contacts should be considered high priority unless records indicate a 

brief exposure. Investigators should also locate priority contacts who have been 

transferred, released, or paroled. For contacts who start treatment, it is important to 

have follow-up supervision to ensure completion of treatment, particularly if the 

contact has been released or paroled. 

Schools 

Contact investigations in schools typically feature a potentially large number of 

contacts and can come with unique challenges because children are involved. Contact 

investigations based in schools may generate community and media attention. 

Therefore, TB control officials should anticipate media coverage and plan a 

collaborative strategy with the school to address parental and community concerns. 

Often, the concern from parents and the community can lead to the entire school being 

tested, regardless of the priority level of the contact. Some parents or guardians may 

not offer consent to have their children assessed for TB. In these circumstances, the 

health department should be prepared to consult with legal experts if necessary. 

Contact investigations in schools typically feature a potentially large 

number of contacts and can come with unique challenges because 

children are involved. 
Module 8—Contact Investigations for Tuberculosis 

88

Identifying and assigning priorities to contacts may be challenging as it can be difficult 

to define the duration and proximity of exposure to the case. If available, contact 

investigators should refer to class assignments, extramural activities, and bus rosters 

to assist in prioritization. Additionally, interviews with the case, his or her parents or 

guardians, and school officials can elicit more information.

Homeless Shelters 

Contact investigations involving shelters and homeless persons can be complicated 

because they often require assessment of a large number of contacts. Additionally, 

these investigations can be difficult because of the transient characteristics and 

lifestyle of some homeless persons. Locating the contacts of a homeless TB case can 

be challenging because of the following potential characteristics associated with 

homeless persons: 

 Migration from one shelter or jurisdiction to another

 Mental illnesses

 Alcohol or drug use

 Periodic incarceration

 Preexisting medical conditions (e.g., HIV)

To help identify contacts, investigators should work with the administrators at 

homeless shelters. Some shelters may maintain daily sign-in sheets or logs. These may 

be used to help identify persons who were at the shelter at the same time as the case. 

However, it is important to note that in some jurisdictions, this information may be 

restricted by law.

To identify and assess additional contacts who may not have been named by the case, 

a location-based approach may be useful (refer to page 54 of this module).
Module 8—Contact Investigations for Tuberculosis 

89

Study Question 8.22 

8.22 List five challenges associated with conducting contact investigations in 

congregate settings. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 106-112

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

90

Conducting Source Case 

Investigations 

What is a Source Case Investigation? 

A source case is a person with TB disease who is responsible for transmitting M. 

tuberculosis to another person or persons. A source case investigation is a method 

used to identify source cases. 

A source case is a person with TB disease who is responsible for 

transmitting M. tuberculosis to another person or persons. A source 

case investigation is a method used to identify source cases. 

The purposes of a source case investigation are to determine 

 Who transmitted M. tuberculosis to a child or to a group of persons (such as 

healthcare workers or correctional facility inmates and staff) who have been 

recently infected with M. tuberculosis

 Whether the source case is still infectious 

 Whether the source case was reported to the health department 

 Whether any other persons were infected by the source case 

 The drug susceptibility test results and genotyping results of the source case 

who transmitted TB to a child 

When Should a Source Case Investigation be Conducted? 

Because source case investigations require a lot of time and effort and generally do not 

result in finding the source case or additional priority contacts, a health department 

must determine when it is necessary to conduct a source case investigation. State or 

local policies should be consulted for the specific criteria for conducting a source case 

investigation. A source case investigation could be considered in the following 

situations: 

 A child 5 years of age or younger has been diagnosed with TB disease 

 An infant 2 years of age or younger has been diagnosed with LTBI 

 Healthcare settings where serial TB testing indicates recent M. tuberculosis

infection in a healthcare worker 
Module 8—Contact Investigations for Tuberculosis 

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 Correctional facilities (e.g., jails, prisons) where TB testing indicates an increase 

in M. tuberculosis infection among inmates or staff 

TB disease in children 5 years of age or younger and LTBI in infants 2 years of age 

and younger indicates that M. tuberculosis was recently transmitted. If exposure to 

an infectious case is unknown, a source case investigation may help find a person 

with undiagnosed TB disease who had contact with the child. It may also find 

additional contacts who have recent M. tuberculosis infection from the same source 

case and need medical attention.

In healthcare settings, if serial TB testing detects a change in a healthcare worker’s 

TST or IGRA status from negative to positive, this could indicate recent TB 

transmission. If the source of exposure is unknown, a source case investigation can 

help determine whether there is unrecognized infectious TB within the healthcare 

facility. For more detailed information, please refer to the CDC’s Guidelines for 

Preventing the Transmission of Mycobacterium tuberculosis in Health-Care 

Settings, available from the CDC website (www.cdc.gov/tb).

If TB testing in correctional facilities indicates an increase in M. tuberculosis

infection among inmates or employees, a source case investigation should be 

considered to determine if there is a case of unrecognized infectious TB in the 

facility.

How Are Source Case Investigations Conducted? 

A source case investigation moves in the opposite direction of a contact investigation,

but the same principles and investigative skills apply. A source case investigation 

usually begins by reviewing existing information (e.g., medical records) to confirm that 

the person has been recently infected with M. tuberculosis. Once it has been 

determined that the person has been recently infected, the next step is to determine 

potential source cases. This is done by interviewing the person who has been recently 

infected or by conducting proxy interviews if the source case investigation involves a 

young child. 

A source case investigation moves in the opposite direction of a 

contact investigation, but the same principles and investigative skills 

apply. 
Module 8—Contact Investigations for Tuberculosis 

92

Conducting Source Case Investigations Involving Children 

If the source case investigation is for a child, their parent, guardian, or someone else 

who knows the child’s lifestyle should be interviewed. The principles of a source case 

interview are similar to the standard TB contact investigation interview; however, the 

emphasis is on finding the source of TB instead of finding contacts to the case.

If the source case investigation is for a child, their parent, guardian, 

or someone else who knows the child’s lifestyle should be 

interviewed. 

During the interview, the investigators should ask about whom the child has spent 

time with at the following locations or activities:

 Home (e.g., persons living in the household, frequent visitors, babysitters) 

 School

 Day care (both inside the home and outside the home) 

 Car pools or buses

 Play groups 

 Recreational activities 

 Places of recent travel 

Additionally, investigators should ask if any person whom the child has spent time with 

has shown symptoms of TB disease. Once potential sources have been identified, they 

should be located and assessed. Assessments during source case investigations 

typically focus on symptom reviews, potentially followed by chest x-rays and 

respiratory specimen collection for AFB smear and culture. Compared to a contact 

investigation, less emphasis is usually placed on testing for infection unless 

investigators are concerned about potential ongoing transmission. 

Conducting Source Case Investigations Involving Healthcare Workers and 

Correctional Facility Staff or Inmates 

When a source case investigation involves a person who is thought to have been 

infected at a healthcare or correctional setting, investigators should determine the 

timeframe during which the person may have been infected. This time frame is 

referred to as the likely exposure period. The exposure period usually begins 8 weeks

prior to the most recent negative TST or IGRA result and ends 2 weeks before the first 

positive TST or IGRA result. The exposure period should be used to determine 
Module 8—Contact Investigations for Tuberculosis 

93

potential source cases. The persons infected with M. tuberculosis should be 

interviewed to identify the following persons or locations visited during the exposure 

period:

 Persons with symptoms of infectious TB disease 

 Persons at increased risk for having TB disease 

 Locations where they spent time during the exposure period where source cases 

may also have been present 

In addition to interviewing newly infected persons, investigators can also identify 

potential source cases by determining which areas of the facility are associated 

with the new TB infections.

Investigators may also review medical records at the facility for recent respiratory 

illnesses that may have been infectious TB disease, but were diagnosed as something 

else. Once the potential source cases have been determined, they should be located 

and assessed for TB disease. For inmates who have been in more than one facility, 

efforts should be made to collaborate with all facilities affected.

 

Data in Source Case Investigations 

If source case investigations are conducted, data should be monitored to determine the 

value of the investigations. Data should include

 Total number of source case investigations conducted

 Number of persons assessed for TB disease

 Number of times a source case was identified

 Whether identified source cases were previously known to the health 

department or if they were detected as a direct result of a source case 

investigation

How Can TB Genotyping Information Contribute to a Source Case 

Investigation? 

TB genotyping can contribute to source case investigations by either confirming or 

disproving a named person as the source case. Additionally, genotyping can identify 

potential source cases that were not originally identified in the investigation.
Module 8—Contact Investigations for Tuberculosis 

94

TB genotyping can contribute to source case investigations by either 

confirming or disproving a named person as the source case as well 

as identifying potential source cases that were not originally 

identified in the investigation. 

For example, if a source case investigation is conducted for a child or another case 

with active TB disease, their TB genotype information can be compared to other recent 

cases in the jurisdiction to determine if the genotypes match. If the genotypes match, 

this could mean that these cases were linked in the same chain of transmission. To 

confirm this, the medical records of the recent case should be reviewed and 

discussions with contact investigators of the case should be held to determine if there 

were any connections between these two cases. 

When a suspected source case is identified, genotyping can support evidence of the 

transmission link to the case if the isolates from both have matching genotypes. If the 

investigation yields no suspected source case, a review of all genotyping results from 

cases living in the same region as the case may identify a genotype match.
Module 8—Contact Investigations for Tuberculosis 

95

Study Question 8.23-8.24 

8.23 What is a source case investigation? 

 

 

 

 

 

 

 

 

 

8.24 How can genotyping contribute to source case investigations? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers to study questions are on pages 99-105

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

96

Case Study 8.8 

Jung is a 3-year-old child who has been diagnosed with TB meningitis. Jung, 

his parents, and his paternal grandmother immigrated to the United States 

from China one year ago.

 

 Should a source case investigation be conducted? 

 

 

 

 

 

 

 What information should you try to obtain? 

 

Answers to case studies are on pages 106-112

 

 

 

 

 

 

 

 
Module 8—Contact Investigations for Tuberculosis 

97

Additional Resources 

1. CDC. Effective TB Interviewing for Contact Investigation: DVD. Atlanta, GA: 

Department of Health and Human Services, CDC; 2006. 

www.cdc.gov/tb/publications/guidestoolkits/Interviewing/default.htm. 

2. CDC. Effective TB Interviewing for Contact Investigation: Self-Study Modules. 

Atlanta, GA: Department of Health and Human Services, CDC; 2006. 

www.cdc.gov/tb/publications/guidestoolkits/Interviewing/default.htm. 

3. CDC. Guidelines for Preventing the Transmission of Mycobacterium tuberculosis

in Health-Care Settings, 2005. MMWR 2005; 54 (No. RR-17). 

www.cdc.gov/mmwr/preview/mmwrhtml/rr5417a1.htm?s_cid=rr5417a1_e. 

4. CDC. Guidelines for the Investigation of Contacts of Persons with Infectious 

Tuberculosis: Recommendations from the National Tuberculosis Controllers 

Association and CDC. MMWR 2005; 54 (No. RR-15). 

www.cdc.gov/mmwr/preview/mmwrhtml/rr5415a1.htm. 

5. CDC. Targeted Tuberculin Testing and Treatment of Latent Tuberculosis 

Infection. MMWR 2000; 49 (No. RR-06). 

www.cdc.gov/MMWR/preview/MMWRhtml/rr4906a1.htm. 

6. CDC. TB Contact Investigation Interviewing Skills Course. Atlanta, GA: 

Department of Health and Human Services, CDC; 2013. 

http://www.cdc.gov/tb/education/skillscourse/default.htm. 

7. CDC. TB Genotyping Information Management System (TB GIMS). Atlanta, GA: 

Department of Health and Human Services, CDC; 2009. 

www.cdc.gov/tb/publications/factsheets/statistics/TBGIMS.pdf. 

8. CDC. Update of Recommendations for Use of Once-Weekly IsoniazidRifapentine Regimen to Treat Latent Mycobacterium tuberculosis Infection. 

MMWR 2018; 67:723–726. 

www.cdc.gov/mmwr/volumes/67/wr/mm6725a5.htm?s_cid=mm6725a5_w
Module 8—Contact Investigations for Tuberculosis 

98

9. CDC. Understanding the TB Cohort Review Process: Instruction Guide. Atlanta, 

GA: Department of Health and Human Services, CDC; 2006. 

www.cdc.gov/tb/education/cohort.htm. 

10. Global TB Institute at Rutgers, the State University of New Jersey. TB 

Interviewing for Contact Investigation: A Practical Resource for the Healthcare 

Worker; 2008. 

http://globaltb.njms.rutgers.edu/educationalmaterials/productfolder/tbinterviewi

ng.php. 

11. Nahid P, Dorman SE, Alipanah N, Barry PM, Brozek JL, Cattamanchi A, Chaisson 

LH, Chaisson RE, Daley CL, Grzemska M, Higashi JM, Ho CS, Hopewell PC, 

Keshavjee SA, Lienhardt C, Menzies R, Merrifield C, Narita M, O’Brien R, 

Peloquin CA, Raftery A, Saukkonen J, Schaaf HS, Sotgiu G, Starke JR, Migliori 

GB, Vernon A. Official American Thoracic Society/Centers for Disease Control 

and Prevention/Infectious Diseases Society of America Clinical Practice 

Guidelines: Treatment of Drug-Susceptible Tuberculosis. Clinical Infectious 

Disease 2016:1–49. https://academic.oup.com/cid/article/63/7/e147/2196792.
Module 8—Contact Investigations for Tuberculosis 

99

Answers to Study Questions 

8.1 What is a TB contact investigation?

A TB contact investigation is a systematic process to

 Identify persons (contacts) exposed to a person with infectious TB disease (a 

case)

 Assess contacts for infection with M. tuberculosis and TB disease 

 Provide appropriate treatment for contacts with LTBI or TB disease 

8.2 What are the goals of a TB contact investigation? 

The goals of a TB contact investigation are to successfully stop TB transmission 

and to prevent future cases and outbreaks of TB disease.

8.3 Which TB cases require a contact investigation? 

A contact investigation is required for all confirmed cases that have infectious 

forms of TB disease (e.g., TB disease of the lungs, airways, or larynx). 

The contact investigation process should be started for persons suspected of 

having infectious TB disease, even before confirmation. This includes persons 

with positive sputum smears and a positive nucleic acid amplification test result. 

For persons with positive sputum smears and a negative nucleic acid 

amplification test result, a contact investigation is not indicated.

For suspect cases with negative sputum smears or sputum smears not 

performed, the contact investigation process should be started if the case has 

abnormal chest x-ray findings consistent with TB disease. 

For suspect cases with negative sputum smear results and no pulmonary cavities, 

a contact investigation should only be considered for certain circumstances, such 

as if the suspect was identified during an outbreak or source case investigation 

that included vulnerable or susceptible contacts. 

If it is later determined that the suspect case does not have infectious TB disease, 

the contact investigation should be stopped.
Module 8—Contact Investigations for Tuberculosis 

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8.4 Who is responsible for conducting TB contact investigations? 

In the United States, state and local health departments are legally responsible 

for the prevention and control of TB in their communities. Thus, they are 

accountable for ensuring contact investigations are performed for TB cases 

reported in their jurisdictions, even when patients are receiving care outside the 

health department.

8.5 Which TB contact investigations should be given priority? 

In general, priority should be given to contact investigations involving

 Highly infectious cases 

 Settings where transmission of M. tuberculosis is likely 

 Contacts at high risk for rapid development of TB disease if infected with M. 

tuberculosis

8.6 What is the infectious period? 

The infectious period is the time during which a case is potentially capable of 

transmitting M. tuberculosis.

8.7 When does the infectious period end? 

The infectious period ends when all of the following criteria are met: 

 Effective treatment 2 weeks or longer;

 Diminished symptoms (e.g., coughing less); and 

 Mycobacteriologic response (e.g., decrease in grade of sputum smear 

positivity).

8.8 What is the main goal of the TB case interview? 

The main goal of the interview with a TB case is to identify contacts who have 

been exposed to M. tuberculosis.

8.9 List three strategies for conducting effective interviews. 

 Have a clear understanding of the objectives of the interview.

 Plan the interview so that each objective is given adequate time.

 Ensure the interview takes place under conditions that protect the privacy of 

the case and encourage effective communication.

 Arrange for the assistance of an interpreter if you do not speak the same 

language as the case.
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 Establish the foundation for an effective working relationship based on trust 

and respect. 

 Explain what a contact investigation is, how a contact investigation protects 

contacts from getting sick with TB disease, and what the case can do to help.

 Begin with an assessment of the case’s knowledge, feelings, and beliefs about 

TB.

 Remain objective, open-minded, and nonjudgmental.

 Ask open-ended questions and listen carefully to the case’s responses.

 Recognize and address the case’s fears and concerns about TB.

 Use opportunities that arise during the interview to educate the case about TB.

8.10 What is a proxy interview? Who may serve as an appropriate proxy? 

Proxy interviews are interviews conducted with persons who are familiar with the 

case’s practices, habits, and behaviors. Potential proxies include family 

members, close friends, or other persons who know the case well. 

8.11 What two factors should be taken into account when determining the priority 

of each contact? 

The priority assigned to each contact should be based on the following:

 Likelihood of transmission from the case 

 Contact’s risk for development of TB disease

8.12 In general, which contacts should be considered priority? 

Priority should be given to contacts who

 Are exhibiting symptoms of TB disease

 Are at risk for rapid development of TB disease 

 Had repeated or extended exposure to the case 

 Were exposed to a case in an environment where transmission was likely, such 

as a small, crowded, or poorly ventilated room or vehicle

 Were exposed to a case undergoing medical procedures that can release 

substantial numbers of M. tuberculosis into the air
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8.13 What are the four main functions of a field visit? 

 Identify additional cases of TB disease

 Identify additional contacts 

 Gather additional information about environmental characteristics of places 

where exposure occurred

 Lay a foundation for additional contact investigation activities at those 

locations, if needed

8.14 List four safety precautions investigators should take while conducting field 

visits.

 Wear an identification badge with a current photograph

 Work in pairs when visiting isolated or dangerous areas

 Have a working cell phone

 Limit visibility of valuable items

 Inform a coworker or supervisor of itinerary, planned route, and expected time 

of return

 Practice appropriate infection control procedures

8.15 List five indicators of recent transmission. 

 TB infection or TB disease in contacts younger than 5 years of age

 Change in contacts’ TST or IGRA status from negative to positive 

 A greater-than-expected rate of TB disease or TB infection among priority 

contacts 

 Evidence of secondary transmission

 TB disease among contacts not initially considered priority (particularly if 

genotypes match that of the case)

8.16 When can a contact investigation be concluded? 

A contact investigation can be concluded if

 All contacts have been assessed for TB infection and disease

 Contacts with LTBI have completed or are close to completing treatment

 No additional secondary cases of TB are found, either among identified 

contacts or through reviewing genotype information
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8.17 What is the purpose of evaluating the TB contact investigation? 

Evaluating the TB contact investigation can help determine how effectively the 

contact investigation activities were conducted and identify areas that may be in 

need of improvement. 

Specifically, the purpose of evaluating contact investigation activities is to 

determine

 If the appropriate contacts were identified

 How many contacts were diagnosed with LTBI

 How many contacts with LTBI completed treatment 

 How many additional cases of TB disease were found 

 How many secondary cases of TB disease completed treatment

 How many contacts were not located

 How many contacts were located, but did not complete assessment 

 The timeliness of identifying and assessing contacts, and starting treatment if 

necessary

 If the contact investigation was performed in all necessary settings

 If the contact investigation was expanded appropriately

8.18 List the 10 steps of the systematic approach to contact investigation. 

1. Review existing information about the case

2. Determine an initial estimate for the infectious period and estimate the 

degree of infectiousness

3. Interview the case

4. Review information and develop a plan for the investigation 

5. Refine the infectious period and degree of infectiousness 

6. Prioritize contacts

7. Conduct field visits 

8. Conduct contact assessments

9. Determine whether to expand or conclude an investigation

10. Evaluate the contact investigation activities 
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8.19 What are the major activities of the contact assessment? 

The major activities of the contact assessment include meeting with the contact 

and conducting a medical evaluation. During the meeting, the investigator should 

collect and confirm information and be sure to maintain the confidentiality of the 

case. Contacts should receive a medical evaluation that includes a medical history, 

HIV test, a TB symptom review, and a TST or IGRA to test for infection with M. 

tuberculosis.

8.20 What is the window period? 

The window period is the time between the contact’s last exposure to the case 

and when a TST or IGRA can reliably detect infection.

8.21 What is window period prophylaxis? Which contacts should receive window 

period prophylaxis? 

Window period prophylaxis is treatment for LTBI that is given to high-risk 

contacts (including children younger than 5 years of age, persons living with HIV, 

and other immunosuppressed persons) who have an initial negative test for TB 

infection less than 8 to 10 weeks after their last exposure to the case.

8.22 List five challenges associated with conducting contact investigations in 

congregate settings. 

Challenges that are sometimes associated with conducting contact investigations 

in congregate settings include

 Large numbers of contacts

 Incomplete data for determining which contacts should be prioritized for 

assessment

 Difficulties related to maintaining confidentiality

 Incomplete information about contacts’ names and locating information

 A need to collaborate with officials and administrators who are not familiar 

with TB

 Media interest, particularly for investigations involving schools or worksites

 Political implications of negative publicity related to TB

 Legal implications for the facility 
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8.23 What is a source case investigation? 

A source case investigation is a method used to identify source cases. A source 

case is a person with TB disease who is responsible for transmitting M. 

tuberculosis to another person or persons. 

8.24 How can genotyping contribute to source case investigations? 

TB genotyping can contribute to source case investigations by either confirming 

or disproving a named person as the source case. Additionally, genotyping can 

identify potential source cases that were not originally identified in the 

investigation.

Cases linked in the same chain of transmission should have matching genotypes. 

If the investigation yields no suspected source case, a review of all genotyping 

results from cases living in the same region as the case may identify a genotype 

match.
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Case Study Answers 

8.1 You are a TB case manager at a busy clinic. Two new TB cases have been assigned 

to you. Indicate which case(s) require a contact investigation and note the reason 

why you made your decision. 

 

 Jose is a 35-year-old agricultural worker diagnosed with extrapulmonary TB 

of the kidneys. He lives with his wife in a small, rented house in a rural area. 

 Dale is a 72-year-old widower who lives alone. He drives himself to the local 

retirement center for bingo and poker four times a week. He was recently 

evaluated for TB disease by his physician because he complained of having a 

cough, shortness of breath, fatigue, and weight loss. His sputum smears 

were positive and his culture results are pending. Dale’s chest x-ray shows a 

cavity in the right upper lobe of his lungs. The physician suspects TB and 

started Dale on a four-drug regimen. 

Dale requires a contact investigation because he has cavitary TB disease 

and his sputum smears are positive. Jose does not require a contact 

investigation because he has extrapulmonary TB of the kidneys, which is 

not infectious.

8.2 Calculate the infectious periods for the following TB cases: 

 

 Isaac is a 42-year-old man who was hospitalized on December 4th with 

symptoms of fever, night sweats, and cough. He was placed in airborne 

infection isolation for two weeks. On the same date (December 4th), AFB 

sputum smears were collected and were reported as positive with final 

cultures pending. Chest x-rays were taken on December 4th and reported as 

abnormal with cavitary disease. Isaac was diagnosed with suspected 

pulmonary TB with appropriate treatment started on December 5th. Isaac 

states that he started coughing around November 6th. His symptoms 

resolved on December 24th. Three consecutive sputum AFB smears were 

negative on February 10th. 

The beginning of Isaac’s infectious period is August 6th (three months 

before the onset of symptoms). For contact investigation purposes, his 

infectious period ends on December 4th since he was effectively isolated 
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and was no longer exposing any contacts. Biologically, the end of the 

infectious period would be February 10th because of the negative sputum 

smears, improved symptoms, and treatment for at least 2 weeks. 

 

 Trang is a 52-year-old woman who had a checkup on May 19th with her 

primary care provider. During this visit, she was found to have an abnormal 

chest x-ray. Sputum collected on the same day was reported as AFB smear 

positive with final cultures pending. On May 20th she was diagnosed with 

suspected pulmonary TB, started appropriate treatment, and was put on 

home isolation. Trang claims she never had a cough or other symptoms. 

Three consecutive induced sputum AFB smears were negative on June 15th, 

June 18th, and June 21st. 

The beginning of Trang’s infectious period is February 19th (three months 

before the first finding consistent with TB). The end of her infectious 

period would be June 21st because she has three negative sputum smears 

and has been on treatment for at least 2 weeks.

8.3 You are the public health worker assigned to conduct a contact investigation for 

Judith, a 73-year-old woman who was recently diagnosed with infectious TB 

disease. Judith lives with her daughter in a small house outside of town. You are 

conducting the case interview in her home. 

 

 What questions should you ask Judith during the interview to learn more 

about her contacts? 

To identify Judith’s contacts, it is important to first determine her period of 

infectiousness. To estimate the start of the infectious period, you should 

ask Judith what symptoms she had (if any) and when they began. To 

determine the end of the infectious period, you should refer to her medical 

record.

Once the infectious period has been estimated, you should ask Judith 

about the following: 

o Where she spent time during her infectious period

o What activities or events she participated in during her infectious period

o Who she spent time with during her infectious period
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8.4 Derrick is a 47-year-old man who has had a severe cough for about two months 

and started treatment for TB disease three days ago. He lives alone in a small 

apartment and works the night shift three times a week with two other employees 

at the convenience store a few blocks away from his home. During the day, 

Derrick goes to friends’ apartments nearby or stays in his apartment to watch TV. 

He often goes to the local bar in his neighborhood with his friends Reggie and 

Melvin. He usually eats at one of two restaurants—the Main Street Diner or Susie’s 

Kitchen. 

 

Derrick says that his girlfriend, Tonya, spends the night with him a few times a 

week, and often brings her 2 year-old son Luke. Derrick also mentions another 

girlfriend, Kelly, who has stayed over about 10 times in the past three months. 

Last month, Derrick spent several days at Kelly’s house, where she lives with her 

mother. 

 

 Based on this information, who are Derrick’s contacts? 

o Tonya and her son 

o Kelly and her mother 

o The two coworkers at the convenience store 

o Friends whom Derrick visits at home, and anyone else who lives in their 

house 

o Reggie, Melvin, and other persons who regularly go to the local bar with 

Derrick

o The bartender 

o Waiters, waitresses, or friends at the two restaurants 

 Which contacts are at higher risk for TB infection and TB disease? 

Tonya and her son are probably the most at risk because they frequently 

stay in Derrick’s apartment. Luke is especially at risk because he is younger 

than 5 years of age. Kelly and her mother are also at risk because Derrick 

stayed at their house during the time he was probably infectious. In 

addition, the friends he spends the most time with—probably Reggie and 

Melvin—would be considered to be at higher risk.
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8.5 One week ago, Hector came to the health department complaining of night 

sweats, weight loss, and a cough that has lasted about a month. His sputum 

smears were positive and he started a four-drug regimen for TB disease. 

 When you interviewed Hector, you found out he lives with his 32-year-old wife, 

Mimi; his two sons, Luis, 2, and Javier, 4; and his mother-in-law, Alma, 65. 

Hector’s cousin, Henry, has stopped by the house a few times in the past month. 

 Hector rides to work 5 days a week in a car with his friend Joe. The ride lasts 

about 30 minutes. 

 Hector works in a mail order packing warehouse. About 100 employees work in 

the main room with Hector, but the room is divided into several sections. There 

are 20 persons in Hector’s section, and 4 of these persons are assigned to work 

closely with Hector. Hector eats lunch outside every day with these 4 coworkers. 

 About twice a week and on weekends, Hector goes to a small neighborhood bar 

located in the basement of a building. At the bar, Hector spends most of the time 

talking to the bartender. He notes that the bartender has been coughing a lot 

lately. 

 Based on this information, who are Hector’s contacts? 

o Household members: Mimi, Luis, Javier, Alma 

o His friend Joe 

o His cousin Henry

o Four coworkers who work closely with Hector 

o The bartender at the local bar 

 Which contacts should be considered a priority? 

All of the contacts listed above should be considered a priority. The highest 

priority should be given to the bartender because he is exhibiting 

symptoms of TB disease. Because of their young age, Luis and Javier are 

also at high risk and should be assessed as soon as possible.
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8.6 Carmen is a 30-year-old woman who was recently diagnosed with infectious TB 

disease. She works at the local community college and lives with her aunt. 

A contact investigator from the local health department is conducting an interview 

with Carmen at Carmen’s home. Three coworkers and her aunt have been 

reported to be contacts by Carmen. 

 Refer back to Figure 8.6 on page 54. Based on what is visible in the photo, is 

there evidence of any additional contacts in Carmen’s home other than her 

aunt? 

The investigator should notice that there are photos of children and others 

who were not mentioned in the interview. In addition, the investigator 

should notice the toys and children’s shoes on the floor. There is also a 

pair of men’s shoes on the floor. Carmen has not mentioned other contacts 

in the house. However the photos, shoes, and toys suggest that there may 

be other persons who live in or visit the house. If additional contacts are 

identified, they should be considered for assessment.

8.7 Priya is a 34-year-old woman who was diagnosed with infectious TB disease. As 

part of her contact investigation, you identified the following priority contacts: 

 Naveen (husband, 35 years old) 

 Sanjay (son, 3 years old) 

 Asha (close friend, 37 years old) 

 Paul (co-worker, 52 years old) 

 Marie (co-worker, 43 years old) 

Five weeks have passed since the contacts were last exposed to Priya while she 

was infectious. These contacts (a total of 5) have been assessed by the contact 

investigation team. None of the contacts were found to have TB symptoms. 

The TB skin test results were as follows: 

 Naveen: 11 mm 

 Sanjay: 0 mm 

 Asha: 5 mm 

 Paul: 3 mm 

 Marie: 0 mm 
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 What follow-up testing and treatment are needed for contacts with a positive 

skin test? 

Both contacts who have a positive TB skin test reaction, Naveen and 

Asha, should be given a chest x-ray to rule out the possibility of TB 

disease. If the chest x-ray is normal, they should complete a full course 

of treatment for LTBI. If the chest x-ray is abnormal, they should be 

evaluated for TB disease, including a sputum examination. 

 Should any follow-up testing or treatment be given to contacts with a 

negative skin test? 

Yes. Because he is at high risk of rapidly developing TB disease if 

infected, Sanjay should start treatment for LTBI if his chest x-rays are 

normal and he has no TB symptoms. His last exposure to Priya while 

she was infectious occurred only 5 weeks ago; therefore, his skin-test 

result may be a false-negative reaction. Sanjay should be given window 

period prophylaxis until 8 to 10 weeks from his last exposure, when he 

should have a repeat skin test. If his chest x-rays are abnormal, he 

should be evaluated for TB disease, including a sputum examination.

 Which contacts should receive a repeat skin test? When should the repeat 

test be performed? 

Sanjay should be retested 8 to 10 weeks after he was last exposed to 

Priya. If Sanjay’s second skin test reaction is negative, he can stop 

taking treatment for LTBI. If his second skin test reaction is positive, 

Sanjay should complete a full course of treatment for LTBI. 

The other contacts who had a negative skin test reaction, Paul and 

Marie, should be retested 8 to 10 weeks after they were last exposed to 

Priya while she was still infectious. Anyone who has a positive reaction 

to the second skin test should complete a full course of treatment for 

LTBI after TB disease has been ruled out.
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8.8 Jung is a 3-year-old child who has been diagnosed with TB meningitis. Jung, his 

parents, and his paternal grandmother immigrated to the United States from 

China one year ago. 

 Should a source case investigation be conducted? 

Yes, a source case investigation should be conducted to locate the 

person who transmitted TB to Jung. When a child has TB infection or 

disease, it indicates that TB was transmitted relatively recently. In Jung’s 

case, his young age indicates that he must have been exposed to 

someone with TB disease during the past 3 years. The person who is 

the source of this exposure is called the source case. In this situation, 

the source case may be a family member or friend (in the United States 

or in China) with infectious, possibly untreated, TB disease. 

 What would be the purpose of conducting a source case investigation for 

Jung? 

The purpose of a source case investigation would be to determine 

o Who transmitted M. tuberculosis to Jung 

o Whether the source case is still infectious

o Whether the source case was reported to the health department 

o Whether any other persons were infected by the source case

o The drug susceptibility test results and genotyping results of the source 

case who transmitted TB to Jung