title: Positive impact of increases in condom use among female sex workers and clients in a medium HIV prevalence epidemic: modelling results from Project SIDA1/2/3 in Cotonou, Benin.
abstract: BACKGROUND
  A comprehensive, HIV prevention programme (Projet Sida1/2/3) was implemented among female sex workers (FSWs) in Cotonou, Benin, in 1993 following which condom use among FSWs increased threefold between 1993 and 2008 while FSW HIV prevalence declined from 53.3% to 30.4%.
  
  
  OBJECTIVE
  Estimate the potential impact of the intervention on HIV prevalence/incidence in FSWs, clients and the general population in Cotonou, Benin.
  
  
  RESULTS
  A transmission dynamics model parameterised with setting-specific bio-behavioural data was used within a Bayesian framework to fit the model and simulate HIV transmission in the high and low-risk population of Cotonou and to estimate HIV incidence and infections averted by SIDA1/2/3. Our model results suggest that prior to SIDA1/2/3 commercial sex had contributed directly or indirectly to 93% (84-98%) of all cumulative infections and that the observed decline in FSWs HIV prevalence was more consistent with the self-reported post-intervention increase in condom use by FSWs than a counterfactual assuming no change in condom use after 1993 (CF-1). Compared to the counterfactual (CF-1), the increase in condom use may have prevented 62% (52-71%) of new HIV infections among FSWs between 1993 and 2008 and 33% (20-46%) in the overall population.
  
  
  CONCLUSIONS
  Our analysis provides plausible evidence that the post-intervention increase in condom use during commercial sex significantly reduced HIV prevalence and incidence among FSWs and general population. Sex worker interventions can be effective even in medium HIV prevalence epidemics and need to be sustained over the long-term.
authors.affiliation: School of Public Health, Imperial College London, London, United Kingdom.
authors.forename: John R
authors.initials: JR
authors.lastname: Williams
authors.affiliation: Unité de recherche en santé des populations, Centre hospitalier affilié universitaire de Québec, Département de médecine sociale et préventive, Faculté de médecine, Université Laval, Québec City, Québec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Alary
authors.affiliation: London School of Hygiene & Tropical Medicine, London, United Kingdom; Centre for Infectious Disease Surveillance and Control, Public Health England, London, United Kingdom.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Lowndes
authors.affiliation: Unité de recherche en santé des populations, Centre hospitalier affilié universitaire de Québec, Département de médecine sociale et préventive, Faculté de médecine, Université Laval, Québec City, Québec, Canada.
authors.forename: Luc
authors.initials: L
authors.lastname: Béhanzin
authors.affiliation: Département de microbiologie, Hôpital Maisonneuve-Rosemont, Montréal, Québec, Canada.
authors.forename: Annie-Claude
authors.initials: AC
authors.lastname: Labbé
authors.affiliation: Faculté des sciences de la santé, Université d'Abomey-Calavi, Cotonou, Bénin; Centre national hospitalier universitaire, Cotonou, Bénin.
authors.forename: Séverin
authors.initials: S
authors.lastname: Anagonou
authors.affiliation: Population Services International, Cotonou, Bénin.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Ndour
authors.affiliation: Dispensaire infections sexuellement transmissibles, Cotonou, Bénin.
authors.forename: Isaac
authors.initials: I
authors.lastname: Minani
authors.affiliation: Programme national de lutte contre le syndrome d'immunodéficience acquise et les infections sexuellement transmissibles, Cotonou, Bénin.
authors.forename: Clément
authors.initials: C
authors.lastname: Ahoussinou
authors.affiliation: Faculté des sciences de la santé, Université d'Abomey-Calavi, Cotonou, Bénin; Centre national hospitalier universitaire, Cotonou, Bénin.
authors.forename: Djimon Marcel
authors.initials: DM
authors.lastname: Zannou
authors.affiliation: School of Public Health, Imperial College London, London, United Kingdom; Unité de recherche en santé des populations, Centre hospitalier affilié universitaire de Québec, Département de médecine sociale et préventive, Faculté de médecine, Université Laval, Québec City, Québec, Canada.
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Boily
mesh_terms: D000293:Adolescent; D000328:Adult; D001499:Bayes Theorem; D001541:Benin / Q000453:epidemiology; D017280:Condoms; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D006801:Humans; D008297:Male; D008875:Middle Aged; D021841:Safe Sex; D011477:Sex Work; D060386:Sex Workers; D055815:Young Adult