Identification of Individuals With Gonorrhea Within Sexual Networks: A Population-Based Study
August 10, 2006
Molecular epidemiology has been used widely to analyze disease outbreaks in hospitals and the community and, for STDs, has the potential to identify individuals in the same sexual network, noted authors of the current study.
In London, the burden of Neisseria gonorrhoeae is a disproportionate 45-50 percent of all cases for England and Wales. From 2003 to 2004, while diagnoses fell 11 percent, mostly among heterosexuals, cases increased 7 percent among men who have sex with men.
Combining molecular typing with epidemiological data obtained through contact tracing offers a combined approach to analyze and elucidate sexual networks that might otherwise remain unknown in such a metropolitan area. The authors examined the application of a molecular typing approach shown to discriminate between individuals without sexual network links in order to test the feasibility of characterizing isolates and identifying clusters of linked patients in the absence of contact tracing data.
Using Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), the authors characterized 2,045 isolates from patients at 13 major London STD clinics between June 1 and Nov. 30, 2004. Within two weeks of receipt of sample, NG-MAST could assign strains. All isolates were assigned a sequence type (strain) based on two highly polymorphic areas of the STD. Strains were matched to individuals' demographic and behavioral data, which was analyzed for congruence among those infected with the same strain.
As a result, researchers revealed 21 prevalent strains, each infecting 20-124 individuals. Of the strains, seven predominated among men who have sex with men. The remaining 14 types were predominant among heterosexuals. No differences were noted between MSM-associated strains in the demographic or behavioral characteristics of those infected. However, among the heterosexual-associated strains, significant distinctions were noted in age (pThe significant heterosexual-strain variability by demographic and behavioral data suggests different strain clusters represent localized transmission, allowing distinct networks to be identified, reported the authors. Furthermore, molecular typing suggests little bridging between MSM and heterosexual networks, concluded authors.
07.08.06; Vol. 368; No. 9530: P. 139-146; Bhudipa Choudhury; Claire L. Risley; Azra C. Ghani; Cynthia J. Bishop; Helen Ward; Kevin A. Fenton; Catherine A. Ison; Brian G. Spratt