Three decades of meningococcal disease in the State of Santa Catarina, Brazil

Consolidation of data on meningococcal disease surveillance for the state of Santa Catarina, Brazil, has provided new insight about the evolution of this disease during the period of 1971-2000. A descriptive epidemiological study, based on retrospective analysis of all cases of meningococcal disease notified in the state of Santa Catarina, linked the surveillance data from the Secretary of the State of Health, magnetic tape records and the data from the national surveillance of diseases of obligatory notification. Following World Health Organization guidelines, cumulative incidence exceeding five cases per 100,000 inhabitants was considered indicative of an epidemic. Official population data from the Fundação Instituto Brasileiro de Geografia e Estatística were used for the incidence denominator. During the 1971-2000 period, 7,893 cases and 1,354 deaths caused by meningococcal disease were reported. This corresponds to a mean of 263 cases and 45 deaths per year, with a mean incidence of 6.4 cases per 100,000 inhabitants and a fatality rate of 17.2 percent. Three distinct epidemiological periods were identified, two of which can be considered epidemic. Two of three distinct epidemiological periods were characterized by an epidemic of meningococcal disease, covering 20 of the 30 years analyzed. Identification of the epidemics and preventive actions, such as vaccination and health education, contributed to the reduction of morbidity and mortality due to this disease.

Effectiveness of a mass immunization campaign against serogroup C meningococci in children in the federal state of Santa Catarina, Brazil

In addition to vaccine efficacy studies, there is a pressing need to evaluate vaccine effectiveness in a way that takes into account the limitations of health care systems in certain settings. An attempt to reach this objective was exemplified by a vaccination campaign against serogroup C meningococci in the federal state of Santa Catarina, in Brazil. A polysaccharide vaccine against serogroup C meningococci was administered to all individuals between 6 months and 14 years of age in March, 1996, in the municipalities that had the highest incidence of meningococcal disease in the previous year. All cases of the disease due to this serogroup observed in Santa Catarina during a 1-year period before and after the vaccination were included in the analysis. The cumulative incidence rate ratio was calculated for the unvaccinated compared to the vaccinated area. As a second step, the ratio of this quantity for the period before and after the vaccination, i.e. the ratio of the rate ratios (RRR), was calculated. One minus RRR was used to estimate the vaccine effectiveness. In the general population, the vaccine effectiveness was 74.3 (95 confidence intervals 52.7 to 99.6). In children 6 months to 14 years, vaccine effectiveness was 93.1 (85.2 to 100). Vaccine effectiveness could not be confirmed within more specific age bands, probably due to the lack of statistical power. It is concluded that group C meningococcal vaccine is effective in reducing the occurrence of meningococcal disease in children 6 months to 14 years of age, and that the ratio of rate ratios (RRR) in a useful method to evaluate vaccine effectiveness.