Serogroup A Neisseria meningitidis of Clone III-1 Present in Western Norway as Early as 1969–73

A clone of serogroup A Neisseria meningitidis recognized by multilocus enzyme electrophoresis and designated as clone III-1, has caused major epidemics of meningococcal disease in various parts of the world since the 1970s. In Norway, serogroup B meningococci have been responsible for an epidemic since the mid-1970s. We have studied a sample of 53 meningococci isolated from patients in western Norway prior to the serogroup B epidemic. 22/35 meningococcal isolates collected 1969–73 represented done III-1, whereas this clone was not found in the 18 isolates from 1962–68. It has been speculated that the epidemic of meningococcal disease in Finland caused by clone III-1 in 1973–75 had spread from an epidemic in USSR that began in 1969. Our findings demonstrate, however, that the clone III-1 was present in Scandinavia in 1969.