Abstract
1 Department of Epidemiology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark
2 Infectious Disease Prevention and Control Unit, Department of Health Promotion and Disease Prevention, 5B The Emporium, C. de Brocktorff Street, Msida MSD 1421, Malta
3 Directorate of Health Information and Research, 95 G'Mangia Hill, G'Mangia PTA 1313, Malta
4 Bacteriology Laboratory, Department of Pathology, Mater Dei Hospital, Msida MSD 2090, Malta
5 Meningococcal Reference Unit, Health Protection Agency, Manchester Medical Microbiology Partnership, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
6 Department of Public Health, Mater Dei Hospital, Medical School, University of Malta, Msida MSD 2090, Malta