Operational Handbooks

3.3.4. Testing for TB infection

TST or IGRA can be used to test for TB infection. People living with HIV who are on ART (including adolescents and children) benefit from TPT regardless of whether they test positive or negative for TB infection. People living with HIV who are not on ART and who test positive for TB infection are shown to benefit more from TPT than those who test negative (49).

3.3.3.2. HIV-negative household and close contacts of a person with pulmonary TB: children and adolescents aged 5 years and over

Target groups for TPT were expanded from the 2018 WHO updated and consolidated guidelines for programmatic management (61) and later versions to include HIV-negative household contacts aged 5 years and over. In this target group, confirmation of TB infection using TST or IGRA, absence of any symptoms of TB, and absence of abnormal findings on CXR may be used to rule out TB disease before starting TPT (28).

3.3.3.1. HIV-negative household and close contacts of a person with pulmonary TB: infants and children aged under 5 years

Children aged under 5 years who are household contacts of a person with bacteriologically confirmed PTB are usually identified through contact investigation or visits to health care facilities. They should be screened for TB symptoms (current cough, fever, not eating well or anorexia, weight loss or failure to thrive, fatigue, reduced playfulness, decreased activity). Those with any one of the symptoms should be evaluated for TB disease, while those who are asymptomatic should be offered TPT.

3.3.2.2. Child and adolescent household contacts

Children aged under 5 years who are household contacts of people with bacteriologically confirmed TB have a significantly higher risk of acquiring TB infection and progressing rapidly to TB disease. Children aged under 2 years are also at particularly high risk for severe and disseminated forms of TB with very high risk of morbidity and mortality. TPT is strongly recommended in all TB household contacts aged under 5 years once TB disease is ruled out.

3.3.1. Introduction

TB infection (previously called latent TB infection) is defined as a “state of persistent immune response to stimulation by M. tuberculosis antigens without evidence of TB disease” (15). The number of people worldwide estimated to have M. tuberculosis infection is 1.7 billion. Further, 7.5 million children aged under 15 years are estimated to be infected with TB every year (11).

2.4.4. Screening of adolescents living with HIV

As highlighted in Box 2.7, systematic screening for TB disease should be conducted among adolescents living with HIV using the WHO-recommended four-symptom screen (W4SS). Those who report any one of the symptoms of current cough, fever, weight loss or night sweats may have TB and should be evaluated for TB and other diseases. Adolescents living with HIV may also be screened using CRP (using a cut-off of >5 mg/L), CXR or mWRDs.