A prospective cohort study was conducted to examine the relationship between vaginal colonization with lactobacilli, bacterial vaginosis (BV), and acquisition of human immunodeficiency virus type 1 (HIV-1) and sexually transmitted diseases in a population of sex workers in Mombasa, Kenya. In total, 657 HIV-1-seronegative women were enrolled and followed at monthly intervals. At baseline, only 26% of women were colonized with Lactobacillus species. During follow-up, absence of vaginal lactobacilli on culture was associated with an increased risk of acquiring HIV-1 infection (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.2-3.5) and gonorrhea (HR, 1.7; 95% CI, 1.1-2.6), after controlling for other identified risk factors in separate multivariate models. Presence of abnormal vaginal flora on Gram's stain was associated with increased risk of both HIV-1 acquisition (HR, 1.9; 95% CI, 1.1-3.1) and Trichomonas infection (HR, 1.8; 95% CI, 1.3-2.4). Treatment of BV and promotion of vaginal colonization with lactobacilli should be evaluated as potential interventions to reduce a woman's risk of acquiring HIV-1, gonorrhea, and trichomoniasis.

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To examine associations between method of contraception, sexually transmitted diseases (STDs), and incident human immunodeficiency virus type 1 (HIV-1) infection, a prospective observational cohort study was done among female sex workers attending a municipal STD clinic in Mombasa, Kenya. Demographic and behavioral factors significantly associated with HIV-1 infection included type of workplace, condom use, and parity. In multivariate models, vulvitis, genital ulcer disease, vaginal discharge, and Candida vaginitis were significantly associated with HIV-1 seroconversion. Women who used depo medroxyprogesterone acetate (DMPA) had an increased incidence of HIV-1 infection (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.4-3.4). In a multivariate model controlling for demographic and exposure variables and biologic covariates, the adjusted HR for HIV-1 infection among DMPA users was 2.0 (CI, 1.3-3.1). There was a trend for an association between use of high-dose oral contraceptive pills and HIV-1 acquisition (HR, 2.6; CI, 0.8-8.5).

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Normal lymphocyte subset values among African children differ from those in other populations. Significant differences are detectable by 3 months of age in CD4+ and CD8+ lymphocyte percentages among perinatally infected infants, which may be useful as an adjunct in diagnosis. Transient differences observed among HIV-1-exposed but uninfected infants could reflect a successful immune response to HIV-1 challenge.

In order to develop a human immunodeficiency virus type 1 vaccine with global efficacy, it is important to evaluate the virus populations that are transmitted to individuals living in high-incidence areas. To determine the nature of the human immunodeficiency virus type 1 population transmitted to women during heterosexual contact, we examined the diversity of the proviral envelope gene in infected cells in both genital secretions and peripheral blood from six recently seroconverted Kenyan women. Heterogeneous virus populations were present in cervical secretions and/or peripheral blood shortly after seroconversion for five of six infected individuals, and tissue-specific variants were identified in several cases.

Cervical and vaginal secretions from 17 women infected with human immunodeficiency virus type 1 (HIV-1) were evaluated daily through the course of one menstrual cycle for HIV-1 DNA (21-31 visits per woman). HIV-1-infected cells were detected in 207 (46%) of 450 endocervical swabs and 74 (16%) of 449 vaginal swabs. There was considerable variability in the percentage of positive swabs from each woman, ranging from 4% to 100% of endocervical swabs and from 0 to 71% of vaginal swabs. In multivariate analyses, plasma HIV-1 RNA was significantly associated with shedding of HIV-1-infected cells; each 1-unit increase in the log of plasma virus load was associated with a 5.6-fold increase in the odds of cervical shedding (95% confidence interval [CI], 2.1-14.8) and a 3.9-fold increase in the odds of vaginal shedding (95% CI, 2.1-7.2). There was no discernible pattern of genital tract shedding with phase of the menstrual cycle and no significant association with serum estradiol or progesterone levels.

This study documents a dramatic decline in the risk of HIV-1 infection while participating in a prospective cohort, with most seroconversions occurring within 1 year of enrollment. Variations in HIV-1 incidence within high-risk populations should be anticipated during the design of vaccine trials.