Children and Adolescents

TST is a method to detect TB infection that involves intradermal injection of tuberculin purified protein derivative (PPD). Previous exposure results in a local delayed-type hypersensitivity reaction within 24–72 hours (6). The reaction is identified as palpable induration at the site of injection. It only indicates hypersensitivity to proteins of the TB bacillus as a result of infection with M. tuberculosis or induced by BCG vaccination. A positive TST does not indicate the presence or extent of TB disease.

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).

Children and adolescents living with HIV should be screened for TB disease at every visit to a health facility or interaction with a health worker, using standard screening questions, as part of routine clinical care (see Chapter 2). Those who do not have any of the symptoms in the questionnaire are unlikely to have TB disease and should be offered TPT, regardless of their ART status. CXR may be offered to adolescents living with HIV and on ART; if there are no abnormal radiographic findings, they may be given TPT.

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).

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.

It is important to exclude TB disease before initiating TPT. A clinical algorithm based on screening for symptoms of TB, history of contact with a person with TB, HIV status, age, TB infection test results and abnormal findings on CXR is recommended (15). Figure 3.4 shows an algorithm applicable to children aged under 5 years with and without HIV, and children and adolescents aged 5 years and over.

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.

Children and adolescents living with HIV are 8–20 times more likely to develop TB disease than those without HIV infection and should be prioritized for systematic evaluation and TPT in all settings (15, 46). Despite major progress in access to and effectiveness of ART, TB is the most frequent cause of acquired immunodeficiency syndrome (AIDS)-related deaths worldwide (47).

The WHO consolidated guidelines on tuberculosis (28) and the WHO operational handbook on tuberculosis (15) identify two broad at-risk child and adolescent populations that need systematic assessment for eligibility for TPT:

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).