From the Guidelines
Yes, TB AFB testing should be performed on family members of a person diagnosed with active tuberculosis, particularly those living in the same household. Testing should include tuberculin skin tests (TST) or interferon-gamma release assays (IGRAs) for all close contacts. For children under 5 years and immunocompromised individuals, testing is especially urgent as they face higher risk of developing severe disease. If the index case has pulmonary TB with positive sputum smears, priority should be given to testing household contacts, as outlined in the guidelines for the investigation of contacts of persons with infectious tuberculosis 1. Family members with positive screening tests should undergo chest X-rays to rule out active disease. Those with latent TB infection may require preventive therapy, typically isoniazid 300mg daily for adults (or 10mg/kg for children) for 6-9 months, or rifampin 600mg daily for 4 months as an alternative, as recommended by the American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America 1. This contact investigation is essential because TB spreads through airborne transmission, and early identification of infected contacts can prevent disease progression and further transmission within the family and community. Some key points to consider in the contact investigation include:
- Deciding to initiate a contact investigation based on the index patient's characteristics and the features of the exposure
- Assigning priorities to contacts based on their individual characteristics and the features of the exposure
- Diagnostic and public health evaluation of contacts, including the use of tuberculin skin tests and interferon-gamma release assays
- Medical treatment for contacts with latent TB infection, including the use of isoniazid and rifampin. It is also important to note that the guidelines for the investigation of contacts of persons with infectious tuberculosis recommend that contact investigations be conducted in a timely and thorough manner, with attention to the potential for transmission in high-risk settings such as households and congregate living settings 1.
From the Research
TB AFB Testing for Family Members
- The decision to perform Tuberculosis Acid-Fast Bacillus (TB AFB) testing on family members depends on various factors, including the presence of TB symptoms, exposure to a TB patient, and the individual's overall health status 2, 3, 4, 5, 6.
- Close contact investigation is a crucial step in TB case finding and control, and testing family members can help identify those who may be infected or at risk of developing TB disease 2.
- Studies have shown that TB infection testing, including TB AFB testing, can be an effective way to identify individuals who are at risk of developing TB disease, especially in high-burden settings 3, 4.
- The use of TB AFB testing in children is also recommended, especially for those under five years of age who are in contact with sputum smear-positive cases of TB 5.
- However, it's essential to consider the risks and benefits of TB AFB testing, including the potential for false-positive results and the need for careful interpretation of test results 5, 6.
Risk Factors for TB Transmission
- Certain risk factors can increase the likelihood of TB transmission, including:
- These risk factors should be taken into account when deciding whether to perform TB AFB testing on family members.
Testing and Treatment
- If TB AFB testing is performed, it's essential to follow up with additional testing and treatment as needed, including: