Prolonged outbreak of B meningococcal disease in the Seine-Maritime department, France, January 2003 to June 2005

Between January 2003 and June 2005, an outbreak of meningococcal disease occured in the department of Seine-Maritime in northern France. Eighty six cases were notified, giving an average annual incidence of 2.7 cases per 100 000 inhabitants, compared with 1.6 in France. An especially affected area was defined as the city of Dieppe and its surrounding area (26 cases, giving an annual incidence of 12 cases per 100 000). This outbreak was due to N. meningitidis phenotype B:14:P1.7,16 belonging to the clonal complex ST-32/ET-5. Over the 31 B14:P1.7,16 cases confirmed by phenotyping methods at the national reference centre for meningococci (CNR, Centre National de Référence des méningocoques) the case-fatality rate (19%) and the proportion of purpura fulminans (42%) were especially high. Teenagers aged between 15 and 19 years and children aged 1 to 9 years were the most affected. In 2003, health authorities put in place enhanced epidemiological surveillance and informed practitioners and population about the disease. In 2004, the national vaccination advisory board studied the opportunity of using a non licensed outer membrane vesicle vaccine developed in Norway which may be effective against the B14:P1.7,16 strain. The Ministry of health decided in 2006 to offer vaccination with this vaccine to people aged 1 to 19 years in Seine- Maritime.