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

OBJECTIVES: To 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. METHODS: Standardized questionnaire administered to a convenience sample of commercial sex workers and trucking company employees enrolled in prospective cohort studies. RESULTS: Ninety-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. CONCLUSION: The 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.

PIP: The acceptability of a theoretical human immunodeficiency virus (HIV) vaccine trial was investigated in HIV-negative commercial sex workers and trucking company employees in Mombasa, Kenya. The 206 women and 201 men who completed questionnaires were already enrolled in a prospective cohort study of high-risk heterosexuals. 95% of men and 98% of women surveyed agreed that acquired immunodeficiency syndrome (AIDS) is a major problem in Kenya; however, only 14% and 6%, respectively, considered themselves at personal risk of infection. Only 4% of male and 1% of female respondents stated they would refuse an HIV vaccine of proven safety and efficacy. However, 91% of women but only 67% of men indicated they would participate in a double-blind, placebo-controlled vaccine trial that involved vaccine-induced HIV seropositivity and prolonged follow-up. The main concerns about participation in such a trial were the positive HIV blood test result and fear of acquiring HIV from the vaccine. 9% of men and 6% of women anticipated they would decrease their condom use as a result of participation in such a trial, and 9% of men and 3% of women thought they would increase their number of sexual partners. Anticipated higher risk behavior was significantly associated with male gender, but not with age, education, history of prostitution or of sex with prostitutes, or current condom use. If and when vaccine trials become possible, this high-risk cohort would comprise an ideal target population; however, concurrent counseling about the need to continue preventive behavioral measures would be a necessity.

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% durig 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.

PIP: 556 male HIV-seronegative male employees of trucking companies in Mombasa, Kenya, were exposed to HIV serological testing, individual counseling, condom promotion, and sexually transmitted disease (STD) diagnosis and management, and returned for at least one follow-up visit in a prospective study to measure changes in sexual behavior and STD incidence after the intervention. There was a significant decrease in sex with high-risk partners over the 1-year period of follow-up, but no change in condom use among study participants; 30% of men reported consistent condom use during extramarital sex throughout the study period. The change in heterosexual risk behavior was accompanied by a significant decrease in the incidence of gonorrhea, nongonococcal urethritis, and genital ulcer disease. The percentage of men reporting extramarital sex decreased from 49% to 36%, while contact with female prostitutes declined from 12% to 6%.

Preparation for AIDS vaccine evaluation in Mombasa, Kenya: establishment of seronegative cohorts of commercial sex workers and trucking company employees.

In preparation for human immunodeficiency virus (HIV) prophylactic vaccine trials, prospective cohorts of HIV seronegative female commercial sex workers and male trucking company employees were established in Mombasa, Kenya, with the aims of defining HIV seroincidence and correlates of HIV seroconversion. Female and male cohorts were followed at 1- and 3-month intervals, respectively, with questionnaires, physical examinations, evaluation for sexually transmitted diseases, and HIV serologic testing. Between February and September, 1993, 1,277 women and 748 men were tested for antibodies to HIV-1. Seroprevalence was 55.4% among commercial sex workers and 17.7% among trucking company employees. Three hundred fifty-two HIV-seronegative women and 507 seronegative men were enrolled in the cohort studies. Annualized seroincidence rates of HIV infection were 16.4% (95% CI 8.8-27.0) among commercial sex workers and 6.6% (95% CI 2.5-13.8) among trucking company employees. These cohorts may be valuable resource for evaluating HIV vaccines and other potential preventive interventions.

Urethral Trichomonas vaginalis infection and HIV-1 transmission.

PIP: The authors' previous study of 504 male workers in Mombasa, Kenya, provides further documentation of an association between urethral infection and increased shedding of HIV in semen. In this study, Trichomonas vaginalis was isolated by culture in 30 men (6%) and was the most commonly isolated urethral pathogen. Men with Trichomonas vaginalis were significantly older than those with Neisseria gonorrhoeae, suggesting infection may be of long duration. 83% of men with unmixed infections were asymptomatic. Since guidelines for syndromic management of urethral discharge do not include Trichomonas vaginalis, even symptomatic men with this condition who seek treatment are unlikely to be diagnosed and properly treated. More research is needed to confirm whether Trichomonas vaginalis (especially long-standing, low-grade infection) enhances male to female HIV transmission. Since an effective, single-dose, low-cost treatment for Trichomonas vaginalis is available worldwide, mass treatment strategies for this sexually transmitted disease could play an important part in HIV prevention in developing countries.^ieng

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.

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.