Neisseria meningitidis serogroup W135 epidemic related to the 2000 Haj, France

Objectives On April 3 and 7, 2000, four cases of Neisseria meningitidis ser ogroup, W135 infection were diagnosed in France in Raj pilgrims and their c lose relatives. Two cases were fatal. Due to the rarity of this strain in F rance, a strain belonging to a clonal complex implicated in several epidemi cs in Europe and North America, and it high mortality observed, The French General Direction of Heal issued recommendations on April 8th for rifampici n chemotherapy for all pilgrims and relatives living in their home. The nat ional disease watch (Institut de Veille Sanitaire, InVS) conducted an inves tigation to describe the epidemic and follow the diffusion of the strain in the population and assess the impact of preventive measures taken as well as need for other specific measures. Methods A case was considered to be confirmed when the strain isolated from usually sterile media after March 22 was found to be identical to the epid emic strain (W135, 2a: P1-2.5 - clonal complex ET37). A case was considered probable when a pilgrim or in a person in contact with a pilgrim had clini cal meningitis (purulent cerebrospinal fluid or purpura fulminans) or when the identified strain was in the W135 serogroup but could not be further id entified. A standardized questionnaire developed in collaboration with the European countries concerned by the epidemic was filled out. Results By November 20, 2000, 25 confirmed and 2 probable cases were identi fied; 85% of the cases occurred during the first 7 weeks of the epidemic. M ortality was 18%. Patients aged over 50 years accounted for 66% of the case s (6/9) occurring before April 9, 2000 and 17% of the cases (3/18) observed after this data, Four patients had single-joint arthritis. No cluster case s could be identified. Four cases occurred among 19, 100 pilgrims (attack r ate 21/100 000), 9 among persons living with pilgrims, 7 among subjects in direct contact with pilgrims but not living with them, and 7 among persons who had no identifiable contact with pilgrims. These last 7 cases occurred after the 3rd week of the epidemic. No cases occurred among persons who had taken rifampicin chemoprophylaxis. Eighteen cases occurred after diffusion of the prophylaxis recommendations including 5 in a population directly co ncerned by the recommendations. Conclusion These data suggest that the epidemic strain is not different fro m other strains in terms of virulence and transmissibility. Eight months af ter the Raj, the number of cases related to the epidemic remained limited i n France The characteristics of the most recent cases do however suggest an epidemic clone persists in the general population. The Direction of Health recommends vaccination using the quadrivalent A,C,W135,Y vaccine for the 2 001 Raj. (C) 2001, Masson, Paris.