Meningococcal disease in Norway 1992-1995. Epidemiology and fatality

We analysed data on all cases of meningococcal disease (MCD) reported to the Norwegian Notification System for Infectious Diseases during the period 1992-1995. For 1994, additional information on fatalities was gathered. Notifications were received from laboratories and clinicians. A total of 586 patients were included. The incidence decreased from 4.6 per 100000 in 1992 to 2.4 in 1994, and then rose to 3.7 in 1995. The initial decrease, a trend also observed in previous years, was seen in both main serogroups B and C. This decline was broken with the increase of serogroup B in 1995. MCD predominantly affects children below 5 years and teenagers. In 1994, 17/105 (16%) patients died. Main risk factors for fatal outcome were age above 30 years (adjusted odds ratio (OR) 19.8; 95% confidence interval (CI) 2.4-164), septicaemia (adjusted OR 9.5; 95% CI 2.2-41) and disease caused by strains B:15 (adjusted OR 6.4; 95% CI 1.2-35) or C:2a (adjusted OR 10.1; 95% CI 1.6-62). We conclude that the incidence of MCD in Norway is unpredictable and that the case fatality rate is substantially higher than previously believed.