title: Sexual seroadaptation: lessons for prevention and sex research from a cohort of HIV-positive men who have sex with men.
abstract: BACKGROUND
  Surveillance data on sexually transmitted infections (STIs) and behavioral characteristics identified in studies of the risk of seroconversion are often used as to track sexual behaviors that spread HIV. However, such analyses can be confounded by "seroadaptation"--the restriction of unprotected anal intercourse (UAI), especially unprotected insertive UAI, to seroconcordant partnerships.
  
  
  METHODS
  We utilized sexual network methodology and repeated-measures statistics to test the hypothesis that seroadaptive strategies reduce the risk of HIV transmission despite numerous partnerships and frequent UAI.
  
  
  RESULTS
  In a prospective cohort study of HIV superinfection including 168 HIV-positive men who have sex with men (MSM), we found extensive seroadaptation. UAI was 15.5 times more likely to occur with a positive partner than a negative one (95% confidence interval [CI], 9.1-26.4). Receptive UAI was 4.3 times more likely in seroconcordant partnerships than with negative partners (95% CI, 2.8-6.6), but insertive UAI was 13.6 times more likely with positives (95% CI, 7.2-25.6). Our estimates suggest that seroadaptation reduced HIV transmissions by 98%.
  
  
  CONCLUSIONS
  Potentially effective HIV prevention strategies, such as seroadaptation, have evolved in communities of MSM before they have been recognized in research or discussed in the public health forum. Thus, to be informative, studies of HIV risk must be designed to assess seroadaptive behaviors rather than be limited to individual characteristics, unprotected intercourse, and numbers of partners. STI surveillance is not an effective indicator of trends in HIV incidence where there are strong patterns of seroadaptation.
authors.affiliation: Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America. jmcconnell@gladstone.ucsf.edu
authors.forename: J Jeff
authors.initials: JJ
authors.lastname: McConnell
authors.forename: Larry
authors.initials: L
authors.lastname: Bragg
authors.forename: Stephen
authors.initials: S
authors.lastname: Shiboski
authors.forename: Robert M
authors.initials: RM
authors.lastname: Grant
mesh_terms: D000222:Adaptation, Physiological; D015331:Cohort Studies; D015658:HIV Infections / Q000503:physiopathology / Q000517:prevention & control*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D012747:Sexual Partners