Bacterial meningitis in adults in Iceland, 1995–2010

Abstract

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.

Keywords::

• Bacterial meningitis
• meningococci
• pneumococci
• meningococcal vaccine

Acknowledgements

The authors are indebted to the Clinical Microbiology Department at the Landspítali University Hospital for information on the organisms and for providing work space; the Pathology Department for information on autopsies; the Vesturhlíð medical records storage for assistance in finding patients records; the Hospital in Akureyri for providing patient information; and finally the medical students Marta Berndsen, Sandra Halldórsdóttir, and Karl Kristinsson for assistance in obtaining data.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.