Module 2: Epidemiology of Tuberculosis
 

Slide 1: (Title Slide.) Self-Study Modules on Tuberculosis, Module 2 

Slide 2: Module 2: Objectives 

At completion of this module, learners will be able to: 

1.	 Describe how the number of TB cases reported in the U.S has changed over the last 60 years 

2.	 List 5 factors that contributed to the increase of TB cases between 1985 and 1992 

3.	 List 3 improvements TB programs made with increased funds that have contributed to a decrease 

in TB cases since 1993 

4.	 List groups of people who are more likely to be exposed to or infected with M. tuberculosis 

5.	 List groups of people who are more likely to develop TB disease once infected with M.
 

tuberculosis
 

Slide 3: Module 2: Overview 

•	 Introduction to TB Epidemiology 

•	 People at High Risk for TB Infection and TB Disease 

•	 Case Studies 

Slide 4: (Title Slide) Introduction to TB Epidemiology 

Slide 5: Epidemiology (1) 

•	 Epidemiology is the study of the distribution and causes of disease and other health problems in 

groups of people. 

Slide 6: Epidemiology (2) 

•	 Epidemiologists: 

o	 Determine frequency and pattern of health problems in communities 

o	 Try to figure out why health problems are occurring 

Slide 7: Global Epidemiology of TB 

•	 TB is one of the leading causes of death due to infectious disease in the world 

•	 Almost 2 billion people are infected with M. tuberculosis 

•	 Each year about: 

o	 9 million people develop TB disease 

o	 1.5 million people die of TB 

Slide 8: TB Reporting in U.S. 

•	 The Report of Verified Case of Tuberculosis (RVCT) is the national TB surveillance data
 

collection form and is used for reporting all verified TB cases to CDC
 

o	 The 50 states, District of Columbia, New York City, Puerto Rico, and 7 other 

jurisdictions in the Pacific and Caribbean report TB cases to CDC 

o	 Health care providers are required by law to report TB cases to state or local health 

departments 

Slide 9: U.S Epidemiology of TB 1953- 1986 

•	 1953: 

o	 More than 84,000 cases of TB 
 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

•	 1953-1984: 

o	 TB cases declined about 6% each year 

•	 1985: 

o	 TB cases reached a low of 22,201 

•	 1986: 

o	 Significant increase in TB cases began 

Slide 10: U.S. TB Resurgence (1) 1986-1992 

•	 [IMAGE: Graph showing the number of TB cases per year from 1982-2014. The 

resurgence of TB in the mid-1980s was marked by several years of increasing case counts 

until its peak in 1992.] 

Slide 11: U.S. TB Resurgence (2) 1986-1992 

•	 Contributing factors: 

o	 Inadequate funding for TB control and other public health efforts 

o	 HIV epidemic 

o	 Increased immigration from countries where TB is common 

o	 Spread of TB in certain settings (e.g., homeless shelters and correctional facilities) 

o	 Spread of multidrug-resistant TB (MDR TB) 

Slide 12: U.S. TB Control and Prevention (1) 1993- 2014 

•	 1993-2014: 

o	 Number of TB cases reported annually in U.S. steadily declined 

• Increased federal funds and other resources allowed TB programs to improve control efforts to: 

o	 Promptly identify persons with TB 

o	 Start appropriate initial treatment for TB cases 

o	 Ensure patients complete treatment 

o	 Conduct contact investigations 

Slide 13: U.S. TB Control and Prevention (2) 1993- 2014 

•	 [IMAGE: Case counts began decreasing again in 1993, and 2014 marked the twenty-second 

year of decline in the total number of TB cases reported in the United States since the peak 

of the resurgence. From 1992 until 2002, the total number of TB cases decreased 5%–7% 

annually. From 2002 to 2003, however, the total number of TB cases decreased by only 

1.4%. In 2014, a total of 9,421 cases were reported from the 50 states and the District of 

Columbia (DC). This represents a decline of 1.5% from 2013 and 64.7% from 1992.] 

Slide 14: Continuing Challenges in TB Control 

•	 TB is reported in almost every state and is increasing in some areas 

•	 More than half of all TB cases in the U.S. are among foreign-born persons 

•	 TB affects racial/ethnic minorities disproportionately 

•	 MDR TB and extensively drug-resistant TB (XDR TB) remain serious public health concerns 

Slide 15: TB Case Rates (1) 

•	 A case rate is the number of TB cases that occur during a certain time period, divided by size of 

the population at that time 

•	 Often expressed in terms of a population size of 100,000 persons 

Slide 16: TB Case Rates (2) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 


 


 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

Example: 

•	 In the U.S. in 2014, there were 9,421 new TB cases in a population size of 318,857,056 

9,421 x 100,000 = 2.96
 

318,857,056
 

•	 In 2014, the U.S. TB case rate was 2.96 TB cases per 100,000 persons (rounded to 3.0) 

Slide 17: TB Case Rates by State, 2014 

•	 [IMAGE: This map shows the TB case rates for all 50 states in the United States. The white 

color indicates that the state has a rate equal to or less than 3.0 TB cases per 100,000. The 

purple color indicates that the state has a rate above 3.0 TB cases per 100,000. States with 

case rates greater than 3.0 include Alaska, Hawaii, California, Texas, Arkansas, Georgia, 

New York, Maryland, New Jersey, and Washington, DC.] 

Slide 18: TB Case Rates (3) 

•	 Health departments, CDC, and others can compare the occurrence of TB in different places, time 

periods, and groups of people using case rates 

•	 Comparisons have shown that rates of TB are higher in certain groups than in others 

Slide 19: Epidemiology of TB, Study Question 2.1 

•	 What happened to the number of TB cases in the United States between 1953 and 1984? 

o	 From 1953 - 1984, the number of TB cases reported in the U.S. decreased by an average 

of 6% each year. 

Slide 20: Epidemiology of TB, Study Question 2.2 

•	 What happened to the number of TB cases in the United States between 1985 and 1992? 

o	 From 1985 - 1992, the number of new TB cases increased by 20%. 

Slide 21: Epidemiology of TB, Study Question 2.3 

•	 Name 5 factors that may have contributed to the increase in the number of TB cases between 

1985 and 1992. 

o	 Inadequate funding for TB control and other public health efforts 

o	 HIV epidemic 

o	 Increased immigration from countries where TB is common 

o	 Spread of TB in certain settings (e.g., correctional facilities and homeless shelters) 

o	 Spread of MDR TB 

Slide 22: Epidemiology of TB, Study Question 2.4 

•	 What happened to the number of TB cases in the United States from 1993 to 2014? 

o	 From 1993 to 2014, there was a steady decline in the number of TB cases reported 

annually in the United States. 

Slide 23: Epidemiology of TB, Study Question 2.5 

•	 Name 3 improvements TB programs were able to make with increased federal, state, and other 

funds that contributed to the decrease in TB cases since 1993. 

o	 Promptly identify persons with TB 

o	 Start appropriate initial treatment for TB cases 

o	 Ensure patients complete treatment 

o	 Conduct contact investigations 
 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 


 

	 

	 

	 

	 

	 

	 

	 

	 

	 

Slide 24: Race and Ethnicity (1) 

•	 TB affects certain racial and ethnic minorities disproportionately 

•	 In 2014, about 85% of TB cases in the U.S. were among racial and ethnic minorities 

•	 Percentage of TB cases in racial and ethnic minorities is higher than expected based on 

percentage of these minorities in the U.S. population
 

Slide 25: Race and Ethnicity (2) 

•	 [IMAGE: Pie chart showing reported TB case rates by race and ethnicity. In 2014, 85% of 

all reported TB cases occurred in racial and ethnic minorities (32% in Asians , 29% in 

Hispanics, 21% in non-Hispanic blacks or African-Americans, 1% in American Indians or 

Alaska Natives, and 1% in Native Hawaiians or Other Pacific Islanders), whereas 13% of 

cases occurred in non-Hispanic whites. Persons reporting two or more races, not including 

persons of Hispanic or Latino origin, accounted for 2% of all cases.] 

Slide 26: Race and Ethnicity (3) 

•	 [IMAGE: This pie chart shows racial and ethnic groups by percentage of U.S. population 

in 2014. In 2014, the U.S. population was 63% non-Hispanic white; 17% Hispanic or 

Latino; 12% non-Hispanic black or African American; 5% Asian; 1% Alaskan Indian or 

Alaskan Native; 0.2% Native Hawaiian or other Pacific Islander; and 2% two or more 

races.] 

Slide 27: Race and Ethnicity (4) 

•	 Disparities may exist due to racial and ethnic minorities having other risk factors for TB, such as: 

o	 Birth in a country where TB is common 

o	 HIV infection 

o	 Low socioeconomic status 

o	 Exposure to TB in high-risk settings 

Slide 28: Relative Risk for TB (1) 

•	 Relative risk is a comparison of case rates between two groups. 

Slide 29: Relative Risk for TB (2) 

Example: 

•	 The case rate for Asians is 17.8 compared to 0.6 for non-Hispanic whites. Therefore, the relative 

risk for Asians is about 29 times higher than non-Hispanic whites 

17.8 (TB case rate for Asians) = 29.6 

0.6 (TB case rate for non-Hispanic whites) 

Slide 30: Relative Risk for TB (3), Race and Ethnicity, 2014 

Race/Ethnicity TB Case Rate Relative Risk 

Asians 17.8 29.6 

Native Hawaiians or 

Other Pacific 

Islanders 

16.9 28.1 

Blacks or African 

Americans 5.1 8.5 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

American Indians 

or Alaska Natives 5.0 8.3 

Hispanics or 

Latinos 5.0 8.3 

Multiple Race 2.8 4.6 

Non- Hispanic 

Whites 0.6 1 

Slide 31: Race and Ethnicity, Study Question 2.6 

•	 Which racial and ethnic groups are disproportionally affected by TB? 

o	 Asians, Native Hawaiians or Other Pacific Islanders, non-Hispanic blacks, Hispanics, and 

American Indians or Alaska Natives are disproportionately affected by TB. 

Slide 32: (Title Slide). People at High Risk for TB Infection and TB Disease 

Slide 33: High-Risk Groups 

•	 High-risk groups can be divided into two categories: 

o	 High risk for exposure to or infection with M. tuberculosis 

o	 High risk for developing TB disease after infection with M. tuberculosis 

Slide 34: People at High Risk for Exposure to or Infection with M. tuberculosis 

•	 Contacts 

•	 People who have come to the U.S. within the last 5 years from areas of the world where TB is 

common 

•	 Persons who visit areas with a high prevalence of TB disease 

•	 People who live or work in high-risk congregate settings 

•	 Health care workers who serve patients at increased risk 

•	 Populations defined locally as having an increased incidence of LTBI or TB disease, possibly 

medically underserved, low-income populations, or persons who abuse drugs or alcohol 

•	 Infants, children, and adolescents exposed to adults who are at increased risk for LTBI or TB 

disease 

Slide 35: People at High Risk for Developing TB Disease after Infection with M. tuberculosis (1) 

•	 People living with HIV 

•	 Children younger than 5 years of age 

•	 People infected with M. tuberculosis within past 2 years 

•	 People with a history of untreated or inadequately treated TB disease 

•	 People who are receiving immunosuppressive therapy 

•	 People with silicosis, diabetes mellitus, chronic renal failure, leukemia, or cancer of the head, 

neck, or lung 

Slide 36: People at High Risk for Developing TB Disease after Infection with M. tuberculosis (2) 

•	 Persons who have had a gastrectomy or jejunoileal bypass 

•	 Low body weight 

•	 Cigarette smokers and persons who abuse drugs or alcohol 

•	 Populations defined locally as having an increased risk 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

Slide 37: High-Risk Groups for TB Infection (1) Contacts 

•	 Contacts are persons who have spent time with someone who has infectious TB disease 

•	 May include: 

o	 Family members 

o	 Coworkers 

o	 Friends 

•	 [IMAGE: Two women talking] 

Slide 38: High-Risk Groups for TB Infection (2) Foreign-Born Persons/Immigrants 

•	 In the U.S., LTBI and TB disease often occur among people born in areas of the world where TB 

is common: 

o	 Asia 

o	 Africa 

o	 Russia 

o	 Eastern Europe 

o	 Latin America 

•	 [IMAGE: Pie chart showing the overall distribution of the countries of birth of foreignborn persons reported with TB in 2014, with the top seven highlighted. The seven top 

countries accounted for 62% of the total, with Mexico accounting for 21%; the Philippines, 

12%; India, 8%; Vietnam, 8%; China, 7%; Guatemala, 3%; and Haiti, 3%. Persons from 

other countries accounted for 38% of foreign-born persons reported with TB.] 

Slide 39: High-Risk Groups for TB Infection (3) Foreign-Born Persons/Immigrants 

•	 [IMAGE: Two pie charts. In 1992, 27% of TB cases occurred in foreign-born persons; 

73% of TB cases occurred in U.S.-born persons. In 2014, 66% of TB cases occurred in 

foreign-born persons; 34% occurred in U.S.-born persons.] 

Slide 40: High-Risk Groups for TB Infection (4) Foreign-Born Persons/Immigrants 

•	 To address high rates of TB in foreign-born persons, CDC and other public health organizations 

are working to: 

o	 Improve the overseas and domestic screening process for immigrants and refugees 

o	 Strengthen the notification system that alerts health departments about the arrival of 

immigrants and refugees with suspected TB disease 

o	 Test recent arrivals from countries where TB is common for TB infection and ensure 

completion of treatment 

Slide 41: High-Risk Groups for TB Infection (5) Foreign-Born Persons/Immigrants 

•	 Individuals applying for immigration and refugee status from overseas: 

o	 Must be screened for TB by panel physicians before entering the U.S. 

o	 Must have completed treatment before entering the U.S. if diagnosed with TB disease 

Slide 42: High-Risk Groups for TB Infection (6) Foreign-Born Persons/Immigrants 

•	 Immigrants living in the U.S. who apply for permanent residence or citizenship: 

o	 Must be tested for TB infection and evaluated for TB disease by U.S.- based civil 

surgeons 

•	 [IMAGE: A doctor and patient reviewing chest x-ray] 

Slide 43: High-Risk Groups for TB Infection (7) Congregate Settings 
 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

•	 In certain congregate settings, the risk of being exposed to TB is higher than other places. This 

may include: 

o	 Correctional facilities 

o	 Homeless shelters 

o	 Nursing homes 

o	 Health care facilities 

Slide 44: High-Risk Groups for TB Infection (8) Congregate Settings 

•	 Risk of exposure to TB is higher than in other settings 

•	 Risk is higher if facility is crowded 

Slide 45: High-Risk Groups for TB Infection (9) Correctional Facilities 

•	 Higher risk in correctional facilities may be due to: 

o	 Incarcerated population includes a high proportion of people at greater risk for TB than 

overall population (risk factors may include HIV-infection and a history of homelessness 

or drug use) 

o	 Physical structure of correctional facilities (e.g., close living quarters, overcrowding, 

potential for inadequate ventilation) 

o	 Movement of inmates into and out of facilities can lead to interruption of therapy 

Slide 46: High-Risk Groups for TB Infection (10) Health Care Workers 

•	 Might be exposed to TB at work 

•	 Risk depends on: 

o	 Number of persons with TB in facility 

o	 Job duties 

o	 Infection control procedures 

•	 [IMAGE: A doctor and patient talking] 

Slide 47: High-Risk Groups for TB Infection (11) Populations Defined Locally 

•	 Populations that may have an increased risk include 

o	 Persons experiencing homelessness 

o	 Medically underserved populations 

o	 Low-income groups 

o	 Persons who abuse drugs or alcohol 

•	 [IMAGE: Homeless man under a bridge] 

Slide 48: High-Risk Groups for TB Infection (12) Populations Defined Locally 

•	 Low-income is linked to higher risk of TB exposure 

•	 Possible reasons include factors associated with low-income: 

o	 Inadequate living conditions 

o	 Crowding 

o	 Malnutrition 

o	 Poor access to health care 

o	 TB rates are 10 times higher for people experiencing homelessness 

Slide 49: High-Risk Groups for TB Infection (13) Children and Adolescents 

•	 High risk if exposed to adults in high-risk groups 

•	 If a child has TB infection or disease, it suggests that: 

o	 TB was transmitted relatively recently 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

o	 Person who transmitted TB to child may still be infectious 

o	 Others may have been exposed 

•	 [IMAGE: Grandfather sitting with his two grandchildren] 

Slide 50: High-Risk Groups for TB Disease (1) Infants and Children Younger than 5 Years 

•	 High risk for rapidly developing TB disease due to underdeveloped immune system 

•	 [IMAGE: Toddler] 

Slide 51: High-Risk Groups for TB Disease (2) People Living with HIV 

•	 HIV is the strongest known risk factor for developing TB disease 

•	 TB is the leading cause of death for people with HIV/AIDS 

•	 Risk of developing TB disease is 7% - 10% each year for people who are infected with both TB 

and HIV (if the HIV is not treated) 

Slide 52: High-Risk Groups for TB Infection, Study Question 2.7 

• Name 7 groups of people who are more likely to be exposed or infected with M. tuberculosis. 

o	 Contacts of people known or suspected to have TB 

o	 People who have come to the U.S. within last 5 years from countries where TB is 

common 

o	 Persons who visit areas with a high prevalence of TB disease 

o	 People who live or work in high-risk congregate settings 

o	 Health care workers who serve high-risk groups 

o	 Populations defined locally as having an increased incidence of LTBI or TB disease, 

possibly medically underserved, low-income populations, or persons who abuse drugs or 

alcohol 

o	 Infants, children, and adolescents exposed to adults who are at increased risk for LTBI or 

TB disease 

Slide 53: High-Risk Groups for TB Infection, Study Question 2.8 

• What are public health agencies doing to address the high rate of TB in foreign born persons? 

o	 Improve the overseas and domestic screening process for immigrants and refugees 

o	 Strengthen the notification system that alerts health departments about the arrival of 

immigrants and refugees with suspected TB disease 

o	 Test recent arrivals from countries where TB is common for TB infection and ensure 

completion of treatment 

Slide 54: High-Risk Groups for TB Infection, Study Question 2.9 

•	 Why is the risk of being exposed to TB higher in certain settings, such as nursing homes or 

correctional facilities? 

o	 Many people in these facilities are at risk for TB disease 

o	 Risk of exposure is higher if facility is crowded 

Slide 55: High-Risk Groups for TB Infection, Study Question 2.10 

•	 What are some reasons why rates of TB disease are higher in correctional facilities? 

o	 The incarcerated population contains a higher proportion of people at greater risk for TB 

than the general population 

o	 An increasing number of inmates are infected with HIV, which means that they are more 

likely to develop TB disease if they become infected with M. tuberculosis 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

	 

o	 Some correctional facilities are crowded and may have inadequate ventilation, which 

promotes the spread of TB 

o	 Therapy can be interrupted when inmates are moved into and out of facilities 

Slide 56: High-Risk Groups for TB Infection, Study Question 2.11 

•	 When a child has TB infection or disease, what does it tell us about the spread of TB in the 

child’s home or community? Name 3 things. 

o	 TB was transmitted relatively recently 

o	 The person who transmitted TB to the child may still be infectious 

o	 Other adults and children in the home or community have probably been exposed to TB 

Slide 57: High-Risk Groups for TB Disease, Study Question 2.12 

•	 Name 8 groups of people who are more likely to develop TB disease once infected. 

o	 People living with HIV 

o	 Children younger than 5 years of age 

o	 People infected with M. tuberculosis within the past 2 years 

o	 People with a history of untreated or inadequately treated TB disease 

o	 People receiving immunosuppressive therapy 

o	 People with silicosis, diabetes mellitus, chronic renal failure, leukemia, or cancer of the 

head, neck, or lung 

o	 Persons who have had a gastrectomy or jejunoileal bypass 

o	 Low body weight 

o	 Cigarette smokers and person who abuse drugs or alcohol 

o	 Populations defined locally as having an increased incidence of disease due to M. 

tuberculosis 

Slide 58: High-Risk Groups for TB Disease, Study Question 2.13 

•	 What is the strongest known risk factor for the development of TB disease? 

o	 HIV infection is the strongest known risk factor for developing TB disease. HIV 

infection weakens the body’s immune system, making it more likely for a person who has 

TB infection to develop TB disease. 

Slide 59: High-Risk Groups for TB Disease, Study Question 2.14 

•	 If a person is infected with both M. tuberculosis and HIV, what are his or her chances of 

developing TB disease? How does this compare to the risk for people who are infected only with 

M. tuberculosis? 

o	 Risk is 7% to 10% each year if person is infected with both M. tuberculosis and HIV and 

the HIV is not treated 

o	 Risk is 10% over a lifetime if person is only infected with M. tuberculosis 

Slide 60: (Title Slide) Case Studies 

Slide 61: Module 2: Case Study 2.1 

For each of the following people, choose the factor(s) known to increase the risk of being exposed to or 

infected with TB 

•	 Mr. Petrov 

o	 Works at a nursing home (risk factor) 

o	 Rides the subway every day 

o	 Emigrated from Russia (risk factor) 
 

 

 

 

 

 

 

 

 

 

 

 

 

• Ms. Montoya 

o Was born in Latin America (risk factor) 

o Has a father who had pulmonary TB disease (risk factor) 

• Ms. Parker 

o Volunteers in the emergency room of an inner-city hospital (risk factor) 

o Works in a day care center 

• Mr. Dudley 

o Was released from prison last year (risk factor) 

o Sleeps in a homeless shelter (risk factor) 

Slide 62: Module 2: Case Study 2.2 

For each of the following people, indicate the factor(s) known to increase the risk of developing TB 

disease once infected 

• Mr. Sims 

o Injects heroin (risk factor) 

o Has HIV (risk factor) 

• Mr. Allen 

o Has diabetes (risk factor) 

o Has high blood pressure 

• Ms. Li 

o Has chest x-ray findings suggestive of previous TB disease (risk factor) 

o Has heart problems 

• Mr. Vinson 

o Is overweight 

o Became infected with M. tuberculosis 6 months ago (risk factor)