# Presentation: 305320

## Testing for 

- TB Disease and Infection

**This is an archived document.**

## Purpose of Targeted Testing

- Find persons with LTBI who would benefit from treatment
- Find persons with TB disease who would benefit from treatment
- Groups that are not high risk for TB should not be tested routinely

## All testing activities should be accompanied 

**by a plan for follow-up care.**

## Groups That Should Be Tested for LTBI

- Persons at higher risk for exposure to or infection with TB
- Close contacts of a person known or suspected
-  to have TB
- Foreign-born persons from areas where TB is
- common
- Residents and employees of high-risk
- congregate settings
- Health care workers (HCWs) who serve high-
- risk clients

## Groups That Should Be Tested 

- for LTBI (cont.)

- Persons at higher risk for exposure to or infection with TB
- Medically underserved, low-income populations
- High-risk racial or ethnic minority populations
- Children exposed to adults in high-risk categories
- Persons who inject illicit drugs

## Groups That Should Be Tested 

- for LTBI (Cont.)

- Persons at higher risk for TB disease once infected
- Persons with HIV infection
- Persons recently infected with *M. tuberculosis*
- Persons with certain medical conditions
- Persons who inject illicit drugs
- Persons with a history of inadequately treated TB

## Administering the Tuberculin Skin Test

- Inject intradermally 0.1 ml of 5
- TU PPD tuberculin
- Produce wheal 6 mm to 10 mm
- in diameter
- Do not recap, bend, or break
- needles, or remove needles from syringes
- Follow universal precautions for infection control

## Reading the Tuberculin Skin Test

- Read reaction 48-72 hours after
- injection
- Measure only induration
- Record reaction in millimeters

## Classifying the Tuberculin Reaction

** ******5 mm is classified as positive in
- HIV-positive persons
- Recent contacts of TB case
- Persons with fibrotic changes on chest radiograph
- 	consistent with old healed TB
- Patients with organ transplants and other
- 	immunosuppressed patients

## Classifying the Tuberculin 

- Reaction (cont.)

****10 mm is classified as positive in
- Recent arrivals from high-prevalence countries
- Injection drug users
- Residents and employees of high-risk congregate settings
- Mycobacteriology laboratory personnel
- Persons with clinical conditions that place them at high risk
- Children <4 years of age, or children and adolescents
- 	exposed to adults in high-risk categories

## Classifying the Tuberculin 

- Reaction (cont.)

****15 mm is classified as positive in
- Persons with no known risk factors for TB
- Targeted skin testing programs should only be
-     conducted among high-risk groups

## Occupational Exposure to TB, 

- Appropriate Cutoff Depends on

- Individual risk factors for TB
- Prevalence of TB in the facility

## Factors that May Affect the 

- Skin Test Reaction

**Type of Reaction**      **Possible Cause**
- False-positive	       Nontuberculous mycobacteria
-                                    BCG vaccination
- 	                          Anergy
- False-negative	       Recent TB infection
-                                    Very young age (< 6 months old)
-                                    Live-virus vaccination
-                                    Overwhelming TB disease

## Anergy

- Do not rule out diagnosis based on negative skin test result
- Consider anergy in persons with no reaction if
-  HIV infected
-  Overwhelming TB disease
-  Severe or febrile illness
-  Viral infections
-  Live-virus vaccinations
-  Immunosuppressive therapy.
- Anergy skin testing no longer routinely recommended

## Boosting

- Some people with LTBI may have negative skin
- test reaction when tested years after infection
- Initial skin test may stimulate (boost) ability to react
- to tuberculin
- Positive reactions to subsequent tests may be
- misinterpreted as a new infection

## Two-Step Testing

- Use two-step testing for initial skin testing of adults
- who will be retested periodically
- If first test positive, consider the person infected
- If first test negative, give second test 1-3 weeks
- 	later
- If second test positive, consider person infected
- If second test negative, consider person
- 	uninfected