Epidemiology of meningococcal meningitis and changes in the surveillance system in Poland, 1970-2006

The objective of this study was to describe the general features of meningococcal meningitis epidemiology in 1970-2006 in Poland, in the context of changes made in surveillance system methods. Because of limited availability of case-based data, a more detailed analysis was performed only for the period 1994-2006 with special focus on case-fatality and diagnostic certainty. The reported annual number of meningococcal meningitis cases reached its peak of 416 (incidence 1.2 per 100,000) in 1981, after which it decreased to 76 cases in 2003 (incidence 0.2), and then increased to 151 cases in 2006 (incidence 0.4 per 100,000). The observed decrease was consistent with the decline in the number of live births and the drop in mortality from meningococcal disease observed using an independent reporting of death certificates. In 1994-2006, 1,677 cases of meningococcal meningitis were registered, with annual incidence varying between 0.2 and 0.5 per 100,000 inhabitants. Median age of patients was 4 years and 73% of cases were under 18 years of age. The majority of cases were caused by group B meningococci, but a trend towards increasing proportion of serogroup C has been identified. Meningococcal meningitis only was reported in 79% of cases, and meningitis with concomitant septicaemia in 21%. The overall case fatality was 3.7% - 4.5% in cases of meningitis only, and 7.1% in cases of meningitis with septicaemia. Based on the case definition introduced in 2005, 88.1% of the cases would be classified as confirmed and 4.8% as probable, whereas 7.1% would not fulfil the criteria of the case definition >Although diagnostic certainty of reported cases has improved in recent years, it is still problematic. Further efforts are needed to increase the proportion of serogrouped cases and assess the burden of meningococcal disease in Poland.