Denis J. Jackson

Hormonal Contraception, Sexually Transmitted Diseases, and Risk of Heterosexual Transmission of Human Immunodeficiency Virus Type 1

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).

Gender differences in HIV-1 diversity at time of infection

To develop an HIV-1 vaccine with global efficacy, it is important to identify and characterize the viruses that are transmitted, particularly to individuals living in areas of high incidence. Several studies have shown that virus from the blood of acutely infected adults was homogeneous, even when the virus population in the index case was genetically diverse. In contrast to those results with mainly male cohorts in America and Europe, in several cases a heterogeneous virus population has been found early in infection in women in Africa. Thus, we more closely compared the diversity of transmitted HIV-1 in men and women who became infected through heterosexual contact. We found that women from Kenya were often infected by multiple virus variants, whereas men from Kenya were not. Moreover, a heterogeneous virus was present in the women before their seroconversion, and in each woman it was derived from a single index case, indicating that diversity was most likely to be the result of transmission of multiple variants. Our data indicate that there are important differences in the transmitted virus populations in women and men, even when cohorts from the same geographic region who are infected with the same subtypes of HIV-1 are compared.

Effect of Circumcision on Incidence of Human Immunodeficiency Virus Type 1 and Other Sexually Transmitted Diseases: A Prospective Cohort Study of Trucking Company Employees in Kenya

To determine the effect of circumcision status on acquisition of human immunodeficiency virus (HIV) type 1 and other sexually transmitted diseases, a prospective cohort study of 746 HIV-1-seronegative trucking company employees was conducted in Mombasa, Kenya. During the course of follow-up, 43 men acquired HIV-1 antibodies, yielding an annual incidence of 3.0%. The annual incidences of genital ulcers and urethritis were 4.2% and 15.5%, respectively. In multivariate analysis, after controlling for demographic and behavioral variables, uncircumcised status was an independent risk factor for HIV-1 infection (hazard rate ratio [HRR=4.0; 95% confidence interval [CI], 1.9-8.3) and genital ulcer disease (HRR=2.5; 95% CI, 1.1-5.3). Circumcision status had no effect on the acquisition of urethral infections and genital warts. In this prospective cohort of trucking company employees, uncircumcised status was associated with increased risk of HIV-1 infection and genital ulcer disease, and these effects remained after controlling for potential confounders.

Cofactors for the acquisition of HIV-1 among heterosexual men: prospective cohort study of trucking company workers in Kenya.

OBJECTIVE To determine the prevalence, incidence, and correlates of HIV-1 infection in a cohort of east African trucking company employees. METHODS HIV-1-seronegative trucking company employees were enrolled in a prospective cohort study and evaluated at 3 monthly intervals for HIV-1 seroconversion, sexually transmitted diseases, and sexual behavior. RESULTS The baseline seroprevalence of HIV-1 among 1500 trucking company employees was 17.8%. Among 752 HIV-1-seronegative men who were followed, the HIV-1 annual seroincidence was 3.1%. In univariate analysis, HIV-1 acquisition was associated with age under 25 years, 10 years or less of sexual activity, occupation as a driver/drivers assistant, occupational travel for more than 14 days per month, religion other than Christian or Muslim, uncircumcised status, sex with a prostitute, sex with a girlfriend/casual partner, extramarital sex, and enrollment seropositivity to Treponema pallidum, Haemophilus ducreyi, and Herpes simplex virus type 2 (all P values < or = 0.05). Using multivariate analysis, HIV-1 acquisition was independently associated with 10 years or less of sexual activity (hazard rate ratio (HRR) 2.0, 95% confidence interval (CI) 1.0-4.3), occupation as a driver/drivers assistant (HRR 3.9, 95% CI 1.7-9.0), religion other than Christian or Muslim (HRR 6.1, 95% CI 1.4-25.7), uncircumcised status (HRR 2.3, 95% CI 1.0-5.0), and unprotected sex with a prostitute (HRR 2.8, 95% CI 1.1-7.0). CONCLUSIONS Trucking company employees had a high HIV-1 seroprevalence rate at enrollment and a high HIV-1 seroincidence during follow-up. Risk factors for HIV-1 seroconversion included years of sexual activity, occupation, religion, uncircumcised status, and unprotected sex with a prostitute. This population is an appropriate target for HIV-1 prevention trials and behavioral interventions.

Decreased incidence of sexually transmitted diseases among trucking company workers in Kenya: results of a behavioural risk-reduction programme

Objective: To establish a cohort of high‐risk individuals suitable for HIV‐prevention trials, and to measure changes in sexual behaviour and sexually transmitted disease (STD) incidence after a behavioural intervention. Design: Prospective cohort study in trucking company depots in Mombasa, Kenya. Participants: A total of 556 male HIV‐seronegative employees of trucking companies. Interventions: HIV serological testing, individual counselling, condom promotion, STD diagnosis and management. Main outcome measures: Sexual risk behaviour and symptomatic STD incidence. Results: Using time‐trend modelling, significant declines in self‐reported high‐risk sexual behaviour were demonstrated during a 1‐year follow‐up. The percentage of men reporting any extramarital sex during the 3‐month period prior to a follow‐up visit decreased from 49% during the first quarter of follow‐up to 36% during the last quarter (P < 0.001). The decline in reported female sex worker contact was from 12% to 6% (P = 0.001). Approximately 30% of men reported consistent condom use during extramarital sex and this percentage remained unchanged during the study period. The incidence of STD declined from 34 per 100 person years (PY) during the first quarter to 10 per 100 PY during the last quarter (P = 0.001). Significant reductions in gonorrhoea (15 to five cases per 100 PY, P = 0.04), non‐gonococcal urethritis (10 to two cases per 100 PY, P = 0.05), and genital ulcer disease (nine to two cases per 100 PY, P = 0.02) were observed. Conclusions: Among truck company workers who participated in a cohort study in Mombasa, Kenya, there was a significant decrease in sex with high‐risk partners, but no change in condom use. The change in heterosexual risk behaviour was accompanied by a significant decrease in incidence of gonorrhoea, non‐gonococcal urethritis, and genital ulcer disease.

Acceptability of HIV vaccine trials in high-risk heterosexual cohorts in Mombasa Kenya.

ObjectivesTo ascertain the level of acceptance of a prophylactic HIV vaccine trial in high-risk HIV-seronegative heterosexual cohorts of men, and women in Mombasa, Kenya, and to assess the anticipated effects of participation on risk behavior. MethodsStandardized questionnaire administered to a convenience sample of commercial sex workers, and trucking company employees enrolled in prospective cohort studies. ResultsNinety-six per cent of respondents believed that HIV was a major problem in Kenya, and 86% of men, and 94% of women perceived themselves at risk. One hundred per cent of women, and 84% of men expressed interest in participation in an HIV vaccine trial, after explanation of the experimental nature of the vaccine, double-blind placebo-controlled design, prolonged follow-up, and potential change in serostatus. Seventeen per cent of men, and 9% of women anticipated an increase in risk behavior as a result of participation. ConclusionThe majority of individuals in two high-risk cohorts were interested in participating in Phase III efficacy trials of HIV vaccines. A significant minority anticipated an increase in risk behavior, which emphasizes the need for intensive counseling, and education throughout a vaccine trial.

Urethral Infection in a Workplace Population of East African Men: Evaluation of Strategies for Screening and Management

Transport workers (n = 504) in Mombasa, Kenya, were screened for urethral infection by history, clinical examination, and laboratory testing of urethral swabs and first-catch urine specimens. The prevalence of Neisseria gonorrhoeae was 3.4%, Chlamydia trachomatis, 3.6%, and Trichomonas vaginalis, 6.0%; more than two-thirds of infections were asymptomatic. A complaint of urethral discharge, dysuria, or both was twice as sensitive as the sign of discharge on physical examination (34.5% vs. 15.5%) in identifying infection. A positive leukocyte esterase dipstick (LED) test on urine predicted infection with a sensitivity of 95.0% and a specificity of 59.3% in symptomatic men and with a sensitivity of 55.3% and a specificity of 82.8% in asymptomatic men. Demographic and behavioral factors were not independent predictors of infection. In resource-poor settings with high prevalences of urethral infection, an effective screening and management strategy would be to treat symptomatic men, as well as asymptomatic men with a positive LED test, for all three infections.

Studies of human immunodeficiency virus type 1 mucosal viral shedding and transmission in Kenya

If human immunodeficiency virus type 1 (HIV-1) vaccines are to be highly effective, it is essential to understand the virologic factors that contribute to HIV-1 transmission. It is likely that transmission is determined, in part, by the genotype or phenotype (or both) of infectious virus present in the index case, which in turn will influence the quantity of virus that may be exchanged during sexual contact. Transmission may also depend on the fitness of the virus for replication in the exposed individual, which may be influenced by whether a virus encounters a target cell that is susceptible to infection by that specific variant. Of interest, our data suggest that the complexity of the virus that is transmitted may be different in female and male sexual exposures.

Stable antenatal HIV-1 seroprevalence with high population mobility and marked seroprevalence variation among sentinel sites within Nairobi, Kenya.

OBJECTIVES To monitor and analyse trends in HIV-1 seroprevalence among antenatal women in Nairobi, Kenya. DESIGN Six sequential surveys were carried out among antenatal clinic attenders at four Nairobi City Council health centres between November 1991 and April 1997. METHODS A total of 6828 women attending for first antenatal clinic visit were administered a standard questionnaire to obtain demographic information and were screened for HIV-1. RESULTS HIV-1 seroprevalence rose from 12.1% in the first survey to 16.2% in the third, completed in October 1993. No rise was observed in subsequent surveys, and seroprevalence among women under the age of 20 declined after the third survey. Significant differences in seroprevalence (P < 0.001) were observed in all survey rounds between women who reported that their province of origin was Nyanza (22.4% overall), compared with those from other provinces in western Kenya (14.1%), and the eastern group of provinces (8.9%). The rise in HIV-1 seroprevalence observed between 1991 and 1993 was almost entirely attributable to the rising seroprevalence among women from Nyanza. There were considerable differences in HIV-1 seroprevalence among the four health centres, partly accounted for by differences in the proportion of clinic attenders from different provinces of origin, which also changed significantly over time. CONCLUSIONS HIV-1 seroprevalence has stabilized in antenatal women attending these health centres in Nairobi, and may be declining among women in the youngest age group. This may reflect stabilization of HIV-1 incidence, but further observation is required. The levels of infection among Nairobi residents reflect the evolution of the HIV epidemic in their provinces of origin, and changing client composition influences HIV-1 seroprevalence at different clinics. HIV sentinel surveillance should be carried out at multiple sites in large urban centres to monitor accurately the evolution of the HIV epidemic and the impact of control efforts in reducing transmission.

Interventions for Commercial Sex Workers and Their Clients

Commercial sex workers (CSWs) have a much higher risk of sexually transmitted disease (STD) and HIV infection than the general population. The daily danger of HIV infection has become a fact of life for almost all CSWs in developing countries. It is within this context that health and social welfare workers attempted to decrease the risk of HIV infection for these women and to measure that decrease in order to direct further intervention efforts. This paper describes the environment strategies and effects outlined in reports of evaluated HIV prevention interventions aimed at CSWs in developing countries and offers perspectives on future directions. Overall the studies presented illustrate that interventions such as STD testing and treatment education programs and condom distribution can reduce HIV rates in the CSW population. Other programs that include elements of individual and community capacity building and efforts to build self-esteem among CSWs are likely to contribute to the success of an intervention. Several recommendations for more specific initiatives are cited.