Comparison of Serogroup W-135 Meningococci Isolated in Sweden during a 23-Year Period and Those Associated with a Recent Hajj Pilgrimage

An outbreak of serogroup W-135 meningococcal disease was reported among pilgrims returning from the annual hajj (pilgrimage to Mecca) in mid-March 2000. Molecular characterization was used to investigate the similarity of the hajj-associated W-135 strains with those isolated in Sweden during a 23-year period (1978 to 2000). The same hajj-associated genosubtype, genosubtype P1.5,2,36b, has been documented in Sweden since 1979, while pulsed-field gel electrophoresis and the sulfadiazine resistance of the W-135 isolates indicated that the outbreak was probably due to a new clone of W-135 meningococci.