The most efficient way to prevent pediatric TB is the prompt evaluation and treatment of children exposed to an infectious adult source case. All close contacts should have a symptom inquiry and TST or IGRA. A chest x-ray and physical exam should be included for all children <5 years old, children with TB symptoms and children older than 5 years of age with a positive TST or IGRA. Children less than 5 years of age with a negative TST or IGRA and no evidence of TB disease by examination or radiology should be given a “window” of preventive therapy to prevent the development of TB disease. This is because it may take up to 8 weeks after infection for the TST or IGRA to convert to positive.116 During this time, untreated infection may progress quickly to severe disease in young children. For children presumed to have been exposed to a drug-susceptible isolate, INH has traditionally been used but RMP may also be used, in accordance with the TB preventive therapy section, detailed previously. Preventive therapy may be discontinued if, after a period of 8 weeks following the last contact, the repeat TST or IGRA is negative, the child remains asymptomatic and is immunocompetent and more than 6 months of age.
In the exposed child, if the initial TST (≥5 mm) or IGRA is positive and there is no clinical or radiographic evidence of disease, then a full course of treatment for TB infection is recommended. When a child <5 years old is diagnosed with TB disease as the index case, reverse contact tracing should be undertaken to identify the infectious source case. Although most source cases are found among adolescent or adult household contacts of the child, other source cases may be found among adolescent or adult non-household contacts, such as babysitters and other caregivers either in or outside the household. Molecular characterization of M. tuberculosis isolates by genotyping can lead to identification of previously unrecognized source cases.117 If the child is hospitalized, it is advisable to screen adolescent or adult visitors for evidence of TB disease.118
The optimal treatment of children in contact with patients with MDR-TB is not well-established. Consultation with a TB specialist is recommended (see Chapter 8: Drug-resistant Tuberculosis for more details).
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