Rifampicin and isoniazid prophylactic chemotherapy for tuberculosis.

Prophylaxis of tuberculosis in children with four month (n = 53) and three month regimens (n = 213) of rifampicin and isoniazid from 1987 to 1996 were tolerated without any toxicity. The reduction in the proportion of paediatric tuberculosis, which was seen after the introduction of chemoprophylaxis with longer regimens in 1981, was maintained with the shorter duration regimens. Altered immigration patterns and a fall in the proportion of infectious tuberculosis, as defined by sputum culture positivity, have been excluded as factors in the reduced paediatric proportion of tuberculosis. The data show such regimens have little toxicity and provide indirect evidence that three months chemoprophylaxis may be as effective as longer regimens.