[Tuberculin response in school children in Pacasmayo, Peru]

To shed some light on the controversy over the protective effect of BCG vaccine and the usefulness of the tuberculin test in countries with a high prevalence of tuberculosis, in September and October 1987 the test was administered to 440 primary school students in the province of Pacasmayo, Peru. The subjects, both vaccinated with BCG and unvaccinated, ranging from 6 to 10 years of age and coming from rural and urban areas with corresponding vaccination coverage of 55 and 60%, were selected by cluster sampling. The tuberculin reaction was negative in 71% of the vaccinated children and 83% of the unvaccinated children, positive in 16 and 11%, respectively, and inconclusive in the remaining subjects. The results suggest that BCG only prevents progression to the serious forms of the infection. The positive reaction indicates infection or reinfection with Mycobacterium tuberculosis regardless of vaccination status. A negative response in unvaccinated children almost always indicates the absence of infection. The inconclusive results in the unvaccinated children could be the result of a nonspecific allergy and, in the vaccinated children, of persistence of the change produced by M. tuberculosis. The percentage of infected schoolchildren was similar to that in other areas of the country with similar epidemiological characteristics. The tuberculin test appears to be especially important when more than five years have passed since vaccination.