From March to October 2008, 214 women were screened and 200 enrolled. Pregnancy was the primary reason for ineligibility. shows the baseline sociodemographic and HIV risk behaviors of the cohort.
Baseline Sociodemographic and HIV Risk Behaviors (Past Month), N=200
Almost all participants self-identified as commercial sex workers and were unmarried, with primary school or less education. Women reported an average of 2.4 regular paying sex partners per day (sex on a regular basis, i.e., weekly) and 1.9 casual sex partners per day (one-time or anonymous partner). Only 3% of women knew the HIV status of their sexual partners. Reported condom use during vaginal sex, sometimes or always, in the past month with regular or casual partners was high, 90% and 88%, but less common with primary partners (boyfriend or husband), 41%, p<0.0001. Anal sex was reported by 37% of women. Frequency of anal sex in the past month varied significantly by partner type, being most common with regular partners and casual partners and less common with primary partners, 35% and 29% vs. 9%, p<0.001. Despite the relatively high frequency of anal sex with regular or casual partners, condoms were less likely to have been used for anal sex than for vaginal sex: 24% and 21% of women reported “never” using condoms for anal sex with regular or casual partners, respectively, compared to 9% and 10% for vaginal sex, p=0.0009. Almost half of the women reported being paid more for sex without a condom. Having sex under the influence of drugs or alcohol and physical or sexual assault related to sex work in the past month occurred in one-third and one-fifth of women, respectively.
Female condom use was low, with only 11% of women reporting regular use; 28% had never used female condoms. Of the 27% (53/200) who disliked female condoms, the major reasons were cost and difficulty accessing (42%), dislodging during intercourse (25%), and overall cumbersomeness (17%).
Use of modern contraceptive methods was high in this population with 52% using nonbarrier methods and 17.5% using male or female condoms (). Only 25% of women reported regular monthly menses, perhaps related to the relatively high proportion of women on hormonal contraception, either injectable (37%) or oral contraceptives (12%).
Baseline Contraception and Vaginal Practices, N=200
Vaginal washing after sex was common with 73% of the women reporting vaginal washing after each sex act and 100% washing at least once daily. Soap and water were most commonly used, but lemon and salt/salt water were also mentioned along with a variety of other agents such as tea leaves, soda, and herbs. Cleaning and preparing for the next client were the most common reason for vaginal washing, however, astringents such as lemon and salt were felt to dry and tighten the vagina as well as kill germs. Lubricant use during sex was reported by about one-third of participants. All lubricant products mentioned contained mineral oil or other products known to degrade latex condoms.
Several HIV risk behaviors declined significantly during the 6-month follow-up period, including the average number of regular partners, 6 vs. 5, p<0.01, the average number of casual partners, 5 vs. 4, p<0.01, and alcohol use 55% (94/71) vs. 49% (86/171), p<0.05. However, the proportion of volunteers reporting unprotected vaginal and anal sex did not change.
Vaginal discharge and abdominal pain were reported by about half of the women at baseline. Clinical pelvic inflammatory disease, defined as lower abdominal tenderness on palpation, cervical motion tenderness, and adnexal tenderness on examination with no other established cause, was diagnosed in 7.2% of women. shows the prevalence of common STI, vaginitis, and genital symptoms at enrollment and month 6. As expected, vaginitis was common, with 38.0% of women diagnosed with bacterial vaginosis, 9.0% with trichomoniasis, and 7.0% with vaginal candidiasis. Gonorrhea and chlamydia diagnoses were lower than expected, 6.0% and 5.5%. Active genital ulcer disease was uncommon despite an HSV-2 seroprevalence of 72%. All STI and vaginitis rates declined on follow-up at month 6.
Prevalence of STIs, Vaginitis, and Genital Symptoms at Baseline and Month 6
In multivariate analyses, diagnosis of chlamydia, gonorrhea, trichomoniasis, or syphilis at baseline was strongly associated with alcohol use (aOR=3.35, 95% CI 1.56, 7.23, p=0.002) and reporting never having anal sex with casual partners (aOR=3.32, 95% CI 1.29–8.55, p=0.013). Chlamydia was strongly associated with age ≤22 (aOR=7.75, 95% CI 1.94–30.88, p=0.004) and any lubricant use (aOR=3.6, 95% CI 0.96–13.14, p=0.057). Trichomoniasis was associated with having more than two dependents (aOR=2.90, 95% CI 1.05–8.00, p=0.04) and reporting never using a condom for vaginal sex with a casual partner (aOR=4.84, 95% CI 1.45–16.15, p=0.01). Reduced risk for HSV-2 Ab seropositivity was associated with age ≤22 (aOR=0.49, 95% CI 0.24–1.0, p=0.05)). Reduced risk for bacterial vaginosis was associated with having anal sex with regular partners (aOR=0.53, 95% CI 0.28–0.99, p=0.045). No significant associations were found for gonorrhea or syphilis.
Five new HIV infections occurred during follow-up (89.3 person years of follow-up). HIV incidence was calculated at 5.6 per 100 person-years (95% CI 1.62, 11.67). HIV incidence was not clearly associated with any demographic, genital behavior, or risk behavior in univariate or multivariate analyses ().
Association Between Incident HIV and Demographic/Behavioral Characteristics or Prevalent STI/Vaginitis
Retention was 93% at 1 month and 86% after 6 months of follow-up. Seasonal migration back to rural hometowns and pregnancy accounted for the majority of loss to follow-up. Thirteen pregnancies occurred during follow-up for an annual pregnancy rate of 14.2 per 1000 women.