An epidemiological study of meningococcal meningitis in the city of S. Paulo, Brazil (population in 1970: 5.931.935 inhabitants) during the period ranging from January 1968 to June 1974 was undertaken. Two outbreaks of meningococcal meningitis occurred during this period in the area under study. The first one began in July 1971, due to serogroup C Neisseria meningitidis; the second one began in april 1974, when the first outbreak had not yet finished and was caused by serogroup A Neisseria meningitidis. The attack rates were higher during the colder months. The majority of the cases occurred in the peripheric districts. Males and infants were at greatest risk. There ivas, however, a significant difference in the age of groups affected by the disease in the first month of both epidemics. The case-fatality ratios (deaths/cases) decreased from 15% (pre-epidemic period of 1968-1970) to 7,9% (epidemic period of 1971-1974.). There was a seasonal variation in the case-fatality ratio during the epidemic period: in colder months it decreased and in warmer months it increased.
Meningitis, meningococcic; Epidemiology; S. Paulo, Brazil; Neisseria meningitidis
