Community outbreak of group B meningococcal disease in southwest France--December 2008 to September 2009.

Between December 2008 and September 2009, 11 cases of invasive meningococcal disease (IMD) group B were reported in a 20 km diameter area in the Département Landes, France. Two of them presented with purpura fulminans and one of them died. The strain responsible for this community outbreak was of the clonal complex ST-269.The incidence rate for IMD group B was 3 per 100,000 inhabitants in Landes from week 40 in 2008 to week 40 in 2009; it was the highest in France during that period. The number of cases observed was significantly higher than expected, especially in young adults (standardised incidence ratio: 23.5, p<0.001). A nightclub located in the 20 km diameter area was a possible place of transmission and a prophylaxis recommended for the staff members helped in decreasing the transmission. However, several cases notified later suggested that the bacteria circulated during several months through healthy carriers in the community. This situation prompted increased surveillance of IMD in Landes and medical practitioners were asked to remain vigilant because of the possible emergence of new cases within the following months.