Bacterial meningitis in adults in Iceland, 1995-2010.

INTRODUCTION: Bacterial meningitis is a serious disease with a mortality rate of 15-20% in adults. We conducted a population-based study of bacterial meningitis in adults (≥ 16 y) in Iceland, 1995-2010. METHODS: Cases were identified based on positive bacterial cultures from cerebrospinal fluid (CSF) and/or the ICD codes for bacterial meningitis. Medical charts were reviewed and outcomes were assessed using the national population registry. The study period was divided into 2 equal parts, 1995-2002 and 2003-2010, before and after implementation of routine childhood vaccination against serogroup C meningococci, respectively. RESULTS: In total, 111 episodes occurred in 110 individuals. The most common causative organisms were Neisseria meningitidis (41%) and Streptococcus pneumoniae (30%). Only 30% of the patients presented with the classical symptom triad of fever, neck stiffness, and an altered mental status. The overall incidence was 3.2/100,000 inhabitants/y, and dropped significantly between the first and second halves of the study (p = 0.03). This drop was due to a reduced incidence of N. meningitidis meningitis: 34 and 12 cases in the first and second periods, respectively (p = 0.006). The incidence of meningitis caused by S. pneumoniae remained unchanged. The case fatality rates were 18% and 13% in the first and second halves of the study, respectively (difference not significant). CONCLUSIONS: The incidence of bacterial meningitis has decreased since the implementation of meningococcal C vaccination in 2002. However, the case fatality rate has remained unchanged.

Bacterial meningitis in children in Iceland, 1975-2010: a nationwide epidemiological study.

BACKGROUND: Bacterial meningitis is a serious and potentially rapid life-threatening disease. Therefore, to ensure appropriate treatment, early recognition of signs and symptoms is imperative, along with knowledge of the epidemiology and microbiology of the disease. METHODS: A long-term, nationwide epidemiological study of bacterial causes of meningitis in children (≤ 18 y) in Iceland during the period 1975-2010 was carried out. A detailed chart review was performed of all cases diagnosed in 1995-2010. RESULTS: A total of 477 children were diagnosed with bacterial meningitis during the period 1975-2010. Of these, 67% were aged under 5 y. The most common pathogens were Neisseria meningitidis (n = 265), Haemophilus influenzae (n = 132), Streptococcus pneumoniae (n = 47), and Streptococcus agalactiae (n = 19); their incidences varied according to age. The age-specific incidence (cases/100,000/y) dropped from 26 in 1975 to 1 in 2010 (p < 0.001). The most common symptoms during the period 1995-2010 were fever (92%), vomiting (67%), nuchal rigidity (60%), and rashes/petechiae (51%). H. influenzae type b disappeared following implementation of Hib vaccination in 1989, and, likewise, the incidence of meningococcal meningitis fell significantly after vaccination against meningococcus serogroup C was initiated in 2002 (p < 0.001). The overall 30-day case fatality rate of bacterial meningitis was 4.4% and remained unchanged during the study period. CONCLUSIONS: The incidence of childhood bacterial meningitis has been reduced significantly by successful vaccinations against H. influenzae type b and N. meningitidis serogroup C. Nevertheless, the case fatality rate has remained unchanged and thus the disease is still a serious threat to childhood health. Further prevention by novel vaccines and improved management of childhood meningitis is an exciting challenge.