Tuberculosis in children: an update.

TB is a common and serious global infection that is spread exclusively from person to person. The initial infection in most healthy people leads to LTBI 95% of the time, but untreated individuals have a 5% to 10% lifetime risk for reactivating their infection to develop highly infectious cavitary pulmonary TB or extrapulmonary disease. Following primary infection progressive disease is more likely to develop in children younger than 5 years old or those who are immunocompromised, particularly those with HIV infection. The diagnosis of TB in most of the world depends on the presence of a clinical illness typical for TB in concert with radiographic changes, the presence of AFB in sputum, or a positive TST. Newer methods of in vitro stimulation of T lymphocytes from TB-infected people to produce interferon may be more accurate than a TST but have yet to be well studied in children. Treatment of children with LTBI is generally 9 months of daily isoniazid unless the child has been in contact with an adult with known isoniazid-resistant TB. For active TB, children generally are treated for 6 months with an initial 2 months of isoniazid, rifampin, and pyrazinamide. Where exposure to an isoniazid-resistant strain is likely, ethambutol is added. After 2 months, pyrazinamide is discontinued unless the patient has been confirmed to have been infected with a resistant strain of M. tuberculosis. BCG, rarely used in the United States, is still considered important to prevent meningitis and miliary disease in very young children in areas of the world with a high prevalence of TB.