Analysis of serovar distribution as a tool in epidemiological studies in gonorrhoea.

During one year 738 gonococcal isolates from 731 consecutive patients with gonorrhoea were collected and classified by co-agglutination using W I and W II/III specific monoclonal antibodies. Eight W I and 30 W II/III serovars (serovariants) were seen. In both serogroups the most frequent serovar among isolates from women and heterosexual men differed from that among isolates from homosexual men. Forty-two per cent of the serovars, were confined only to one subpopulation, i.e. women, heterosexual men or homosexual men, representing 19 (3%) of the 738 isolates. Out of these 19 isolates 42% were acquired abroad compared with 12% of the 653 isolates in the serovars shared between two or all three subpopulations (p less than 0.005). Imported W I isolates were often of the same serovar that dominated in Stockholm. W II/III isolates acquired abroad were often of unusual serovars (p less than 0.0005) and might be a source of future changes of the serovar pattern in Sweden. In this way we can follow the introduction of new serovars into our society and their circulation between the subpopulations.