Summaryobjective To estimate the female sex worker population size in three cities in Cô te d'Ivoire and in Kisumu, Kenya.methods Capture-recapture was used, calculating size estimates by first 'tagging' a number of individuals and, through an independent recapture, calculating the proportion of overlap. The same procedures were used in all four cities. In the first phase, members of the target population were 'captured' and 'marked' by giving them a capture card. Six days later, in the same places and at the same time, a second sample was 'captured', which comprised a certain number of people who were captured in the first round. During the exercise, questions were asked to estimate the coverage of the sex worker clinics. conclusions Capture-recapture was successfully applied to estimate the population size of female sex workers. These estimations were urgently needed to help mobilize an increased response to HIV, to assess programme coverage and to estimate potential impact of the targeted intervention.

BackgroundIn 1997, a survey in Kisumu found a prevalence of HIV infection among female sex workers (FSW) of 75%. Only 50% reported using a condom with the last client. In 2008, we conducted another survey to collect data to inform an intervention targeting FSW in Kisumu.MethodsIn 2008 FSW were recruited by respondent-driven sampling. Women completed a questionnaire and were tested for HIV and other sexually transmitted infections (STIs). Multiple logistic regression analysis was done to explore factors associated with HIV-infection, and with condom use. Prevalence of HIV infection was compared in the two surveys from 1997 and 2008. Multivariate analysis was used to assess whether a change in HIV prevalence between the two surveys could be explained by changes in socio-demographic characteristics and/or behavioral factors.Results481 FSW participated in the 2008 study. HIV prevalence was 56.5% (95% CI 52.0–61.6). Factors independently associated with HIV were age older than 29 years; being a widow; STI treatment in the past year; herpes simplex virus Type-2 infection; bacterial vaginosis; and trichomoniasis. Condom use with last client was reported by 75.0% (95% CI 70.9–78.9). Predictors of condom use with the last client were age older than 29 years; higher price paid by last client; ever having been tested for HIV. Predictors of unprotected sex were being drunk during last sex act; usually having sex during menses; and STI treatment in the past year. The odds ratio of HIV infection associated with year of survey was 0.49 (95% CI 0.33–0.75) after adjusting for socio-demographic and behavioral factors.ConclusionsThe prevalence of HIV among FSW in Kisumu was found to be lower in 2008 than in 1997, while reported condom use was higher. However, access to HIV/STI prevention and care services needs to improve to further decrease HIV transmission between FSW and their clients.

Human immunodeficiency virus type 1 (HIV-1) epidemiology among residents of a rural agricultural plantation in Kericho, Kenya was studied. HIV-1 prevalence was 14.3%, and was higher among women (19.1%) than men (11.3%). Risk factors associated with HIV-1 for men were age (>or=25 years), marital history (one or more marriages), age difference from current spouse (>or=5 years), Luo ethnicity, sexually transmitted infection (STI) symptoms in the past 6 months, circumcision (protective), and sexual activity (>or=7 years). Among women, risk factors associated with HIV-1 were age (25-29 years, >or=35 years), marital history (one or more marriages), age difference from current spouse (>or=10 years), Luo ethnicity, STI symptoms in the past 6 months, and a STI history in the past 5 years. Most participants (96%) expressed a willingness to participate in a future HIV vaccine study. These findings will facilitate targeted intervention and prevention measures for HIV-1 infection in Kericho.

In preparation for HIV-1 vaccine trials in Kenya, 2801 study volunteers, from a tea plantation in Kericho, were recruited as part of a prospective vaccine cohort development study. Cryopreserved plasma was available from 401 HIV-positive volunteers, and was the source of viral RNA for genotyping by the multiregion hybridization assay (MHA). Logistic regression was performed to determine association of risk factors and HIV-1 recombinant and dual infections. At baseline, HIV-1 subtype A was the dominant circulating pure subtype (56%), followed by subtype D (10%) and C (5%). Recombinant HIV-1 strains accounted for almost one-third of all infections (29%), with 7% infected with a dual strain of the HIV-1 variants described. A higher number of HIV-1 recombinant and dual infections was observed among volunteers who were 18-24 and 25-29 years of age, affiliated with the Luo tribe, had been married two or more times, reported not being circumcised, and had STI symptoms in the past 6 months. Adjusted odds ratios (AOR) significantly associated with HIV-1 recombinant and dual infection were age difference from current spouse (5-9 years; AOR = 2.5, 95% CI = 1.2-5.3 and > or = 10 years; AOR = 3.1, 95% CI = 1.5-6.4) and reported STI symptoms in the past 6 months (AOR = 4.8, 95% CI = 2.0-11.6), respectively. In conclusion, our results suggest that there is considerable heterogeneity with respect to HIV-1 subtype diversity in this population that should be considered in the planning for future vaccine trials in the region.