[Description of a school micro-epidemics of tuberculosis].

BACKGROUND: Despite the progressive decrease in the incidence of tuberculosis, this disease continues to be a problem of Public Health Care, maintaining endemic levels which sporadically allow the appearance of epidemic outbreaks, particularly among the young population. A small outbreak of tuberculosis among COU (high school) students is presented. METHODS: Following the detection of a case of open, cavitary pulmonary tuberculosis, the authors studied 47 students and 12 teachers who were distributed into two groups according to the number of weekly class hours shared with the index case (group A 4 hours and group B 21 hours). RESULTS: The index case began with respiratory symptomatology in the month of September 1990 and was not diagnosed of tuberculosis until January 1991, having shared classes with school mates for 3 months. In April 1991 two patients were diagnosed with pleural tuberculosis and it was at this time that the study was initiated. A prevalence rate of positive tuberculin of 59% was detected among the students of group A and 93% among those of group B, with an incidence of tuberculous disease of 12% and 20% in the two groups respectively. No teachers were found to have the disease and the tuberculin test was heavily influenced by previous BCG vaccination. CONCLUSIONS: Both the prevalence of infection and the incidence of tuberculosis was very high in all two groups. The authors consider that the development of this small outbreak in a school was due to deficiencies in primary health care (low index of suspicion and excessive delay), specialized care (delay in declaration of cases) and epidemiologic departments (deficient study of contacts).