[Tuberculosis outbreak at a public school]

At school there are special circumstances of living together and a particular susceptibility, which favour the emergence of tuberculosis microepidemics. We report here the microepidemic occurred at a school among 9-year old children.

After ruling out a possible familiar source in a child with pulmonary tuberculosis, we detected a case with high bacillar shedding in a female teacher and conducted a tuberculin search among children and teachers, initially outlining the theoretical groups at risk. Tuberculin positive children underwent chest-X-ray and when abnormalities were found, children were derived to the pediatrician for chemotherapy. All converters received secondary chemoprophylaxis and all non-respondents primary chemoprophylaxis.

The classroom where the teacher spent most of het time had a higher rate of converters (70%) than other classroom, where the index teacher spent only a partial time (40%; RR: 1.75; CI: 1.06-2.88) or the collective of teachers (45.4%; RR: 1.45; CI: 0.94-2.23). Three additional cases of secondary disease were detected, all of them children. The initial compliance with chemoprophylaxis was greater among (for) children (97.0%) than among teachers (41.6%). Among children there was one case of tuberculin conversion compared with three cases among teachers. No additional cases were detected; also, an abnormal rate of reactors outside the initially studied groups was also not detected.

Our results somehow agree with those reported from other school outbreaks. To note the anergy and lack of symptoms in the index case and the suggestion to delineate the degree of spending hours together to identify groups with a higher theoretical risk of being infected. Thus, an unnecessary expense of resources and a social alarm would be avoided.