Trends in HIV-1 incidence in a cohort of prostitutes in Kenya: implications for HIV-1 vaccine efficacy trials

Developing HIV risk prediction tools in four African settings

OBJECTIVE

HIV risk prediction tools are a critical component of efforts to end the HIV pandemic. We aimed to create and validate tools for identifying individuals at highest risk of prevalent and incident HIV in an African setting.

METHODS

We used Logistic regression and Poisson regression to determine risk factors for HIV prevalence and incidence in a multi-country HIV vaccine trial preparedness cohort study among individuals at high risk of HIV, and used the identified factors to create and validate tools that predict HIV risk. We also assessed the performance of the VOICE risk score in predicting HIV incidence among women in the cohort.

RESULTS

The prevalent HIV prediction tool created had good predictive ability [area under the curve (AUC) = 0.70, 95% CI 0.66-0.74]. It included the following participant variables: age, sex, recreational drug use, unprotected male-to-male anal sex, a sexual partner who had other partners, transactional sex and having a partner who was a long-distance truck driver/miner. It was not possible to create a valid HIV incidence prediction tool. Participants with high VOICE risk scores (≥7) had slightly higher HIV incidence but this tool performed poorly within our study (AUC = 0.58, 95% CI 0.51-0.64: Harrell's concordance index = 0.59).

CONCLUSION

We created a prevalent HIV prediction tool that could be used to increase efficiency in diagnosis of HIV and linkage to care in sub-Saharan Africa. Existing incident HIV prediction tools may need modification to include context-specific predictors such as calendar period, participant occupation, study site, before adoption in settings different from those in which they were developed.

Estimation of HIV incidence from analysis of HIV prevalence patterns by age and years since starting sex work among female sex workers in Zimbabwe

OBJECTIVES

To estimate HIV incidence among female sex workers (FSW) in Zimbabwe: using HIV prevalence by age and number of years since started selling sex (YSSS).

DESIGN

We pooled data from FSW aged 18-39 participating in respondent-driven sampling surveys conducted in Zimbabwe between 2011-2017.

METHODS

For each year of age, we estimated: HIV prevalence (Pt) and the change in HIV prevalence from the previous age (Pt-Pt-1). We then estimated the rate of new HIV infections during that year of age: It = Pt-Pt-1/(1-Pt-1), and calculated HIV incidence for 18-24 and 25-39 year-olds separately as the weighted average of It. We estimated HIV incidence for FSW 1-5 years and 6-15 years since first selling sex using the same approach, and compared HIV prevalence among FSW first selling sex at their current age with the general population.

RESULTS

Among 9,906 women, 50.2% were HIV positive. Based on HIV prevalence increases by age, we estimated an HIV incidence of 6.3/100 person-years at risk (pyar) (95%CI 5.3,7.6) among 18-24 year-olds, and 3.3/100 pyar (95% CI 1.3,4.2) among 25-39 year-olds. Based on prevalence increases by YSSS, HIV incidence was 5.3/100 pyar (95% CI 4.3,8.5) between 1-5 years since first selling sex, and 2.1/100 pyar (95% CI -1.3, 7.2) between 6-15 years.

CONCLUSIONS

Our analysis is consistent with very high HIV incidence among FSW in Zimbabwe, especially among those who are young and recently started selling sex. There is a critical need to engage young entrants into sex work in interventions that reduce their HIV risk.

Derivation of an HIV Risk Score for African Women Who Engage in Sex Work

No tool exists to stratify HIV risk in contemporary African female sex worker (FSW) populations. Data from a cohort of HIV-negative FSWs in Mombasa, Kenya from 2010 to 2017 were used to conduct a survival analysis assessing predictors of HIV infection. Stepwise regression was used to construct a multivariable model that formed the basis for the score. Seventeen HIV infections occurred over 1247 person-years of follow-up contributed by 670 women. Using depot medroxyprogesterone acetate (DMPA), having a curable sexually transmitted infection (STI), and being married contributed points to the score. HIV incidence was 0.85/100 person-years in a lower-risk group and 3.10/100 person-years in a higher-risk group. In a cohort with overall HIV incidence < 1.50/100 person-years, this risk score identified a subgroup of FSWs with HIV incidence > 3.00/100 person-years, which is the threshold used by the World Health Organization for initiating pre-exposure prophylaxis (PrEP). If validated in an external population, this tool could be useful for targeted PrEP promotion among higher-risk FSWs.

Older age at infection and nulliparity are associated with long-term non-progression in female sex workers infected with non-subtype B HIV-1

Studies have reported on HIV-infected, antiretroviral therapy (ART)-naïve individuals who show minimal disease progression despite prolonged infection. The characteristics of these long-term non-progressors (LTNPs) are not well-characterized in populations predominantly infected with non-subtype B HIV-1. Female sex workers in Mombasa, Kenya who acquired HIV-1 were studied to ascertain immunologic disease progression. Long-term non-progression was defined as an ART-naïve duration of infection ≥7 years and a majority of CD4+ cell counts ≥600 cells/µl with a non-declining CD4+ trend. Correlates of long-term non-progression were determined using multivariable logistic regression. Between February 1993 and March 2014, 332 women acquired HIV-1. Of these, 77 (23%) had ≥7 years of follow-up and 13 (17%) were categorized as LTNPs. Factors associated with long-term non-progression included age >30 years at infection (aOR = 9.41, 95% CI: 1.48–59.86, P = 0.005) and nulliparity (aOR = 20.19, 95% CI: 1.36–299.90, P = 0.03). Each log10 copies/ml increase in viral load (VL) set point was associated with a lower likelihood of being a LTNP (aOR = 0.31, 95% CI: 0.12–0.79, P = 0.01). These findings suggest that age and parity may influence the likelihood of long-term non-progression through mechanisms that are not mediated by the effects of these variables on VL. Future studies should seek to determine whether the associations presented are reproducible.

Trends in HIV Prevention, Treatment, and Incidence in a Hyperendemic Area of KwaZulu-Natal, South Africa

IMPORTANCE

In Africa, the persistently high HIV incidence rate among young women is the major obstacle to achieving the goal of epidemic control.

OBJECTIVE

To determine trends in coverage of HIV prevention and treatment programs and HIV incidence.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study consisted of 2 sequential, community-based longitudinal studies performed in the Vulindlela and Greater Edendale area in KwaZulu-Natal, South Africa. Participants enrolled from June 11, 2014, to June 22, 2015 (2014 survey), with a single follow-up visit from June 24, 2016, to April 3, 2017 (2016 cohort), or enrolled from July 8, 2015, to June 7, 2016 (2015 survey), with a single follow-up visit from November 7, 2016, to August 30, 2017 (2017 cohort). Men and women aged 15 to 49 years were enrolled in the 2014 and 2015 surveys, and HIV-seronegative participants aged 15 to 35 years were followed up in the 2016 and 2017 cohorts. Analysis was conducted from January 1 through December 31, 2018.

EXPOSURES

HIV prevention and treatment programs in a real-world, nontrial setting.

MAIN OUTCOMES AND MEASURES

Trends in sex- and age-specific HIV incidence rates, condom use, voluntary medical male circumcision, knowledge of HIV-seropositive status, uptake of antiretroviral therapy, and viral suppression.

RESULTS

A total of 9812 participants (6265 women [63.9%]; median age, 27 years [interquartile range, 20-36 years]) from 11 289 households were enrolled in the 2014 survey, and 10 236 participants (6341 women [61.9%]; median age, 27 years [interquartile range, 20-36 years]) from 12 247 households were enrolled in the 2015 survey. Of these, 3536 of 4539 (annual retention rate of 86.7%) completed follow-up in the 2016 cohort, and 3907 of 5307 (annual retention rate of 81.4%) completed follow-up in the 2017 cohort. From 2014 to 2015, condom use with last sex partner decreased by 10% from 24.0% (n = 644 of 3547) to 21.6% (n = 728 of 3895; P = .12) in men and by 17% from 19.6% (n = 1039 of 6265) to 16.2% (n = 871 of 6341; P = .002) in women. Voluntary medical male circumcision increased by 13% from 31.9% (1102 of 3547) to 36.1% (n = 1472 of 3895); P = .007) in men, and the proportion of women reporting that their partner was circumcised increased by 35% from 35.7% (n = 1695 of 4766) to 48.2% (n = 2519 of 5207; P < .001). Knowledge of HIV-seropositive status increased by 21% from 51.8% (n = 504 of 3547) to 62.9% (n = 570 of 3895; P < .001) in men and by 14% from 64.6% (n = 1833 of 6265) to 73.4% (n = 2182 of 6341; P < .001) in women. Use of antiretroviral therapy increased by 32% from 36.7% (n = 341 of 3547) to 48.6% (n = 432 of 3895; P < .001) in men and by 29% from 45.6% (n = 1251 of 6265) to 58.8% (n = 1743 of 6341; P < .001) in women; HIV viral suppression increased by 20% from 41.9% (n = 401 of 3547) to 50.3% (n = 456 of 3895; P = .005) in men and by 13% from 54.8% (n = 1547 of 6265) to 61.9% (n = 1828 of 6341; P < .001) in women. Incidence of HIV declined in women aged 15 to 19 years from 4.63 (95% CI, 3.29-6.52) to 2.74 (95% CI, 1.84-4.09) per 100 person-years (P = .04) but declined marginally or remained unchanged among men and women in other age groups.

CONCLUSIONS AND RELEVANCE

This study showed a significant decline in HIV incidence in young women; however, to further reduce HIV incidence, HIV prevention and treatment program coverage must be intensified and scaled up.

Is knowledge of HIV status associated with sexual behaviours? A fixed effects analysis of a female sex worker cohort in urban Uganda

INTRODUCTION

Female sex workers (FSWs) have strong economic incentives for sexual risk-taking behaviour. We test whether knowledge of HIV status affects such behaviours among FSWs.

METHODS

We used longitudinal data from a FSW cohort in urban Uganda, which was formed as part of an HIV self-testing trial with four months of follow-up. Participants reported perceived knowledge of HIV status, number of clients per average working night, and consistent condom use with clients at baseline, one month, and four months. We measured the association between knowledge of HIV status and FSWs' sexual behaviours using linear panel regressions with individual fixed effects, controlling for study round and calendar time.

RESULTS

Most of the 960 participants tested for HIV during the observation period (95%) and experienced a change in knowledge of HIV status (71%). Knowledge of HIV status did not affect participants' number of clients but did affect their consistent condom use. After controlling for individual fixed effects, study round and calendar month, knowledge of HIV-negative status was associated with a significant increase in consistent condom use by 9.5 percentage points (95% CI 5.2 to 13.5, p < 0.001), while knowledge of HIV-positive status was not associated with a significant change in consistent condom use (2.5 percentage points, 95% CI -8.0 to 3.1, p = 0.38).

CONCLUSIONS

In urban Uganda, FSWs engaged in safer sex with clients when they perceived that they themselves were not living with HIV. Even in communities with very high HIV prevalence, the majority of the population will test HIV-negative. Our results thus imply that expansion of HIV testing programmes may serve as a behavioural HIV prevention measure among FSWs.

A 15-year study of the impact of community antiretroviral therapy coverage on HIV incidence in Kenyan female sex workers

OBJECTIVE

To test the hypothesis that increasing community antiretroviral therapy (ART) coverage would be associated with lower HIV incidence in female sex workers (FSWs) in Mombasa District, Kenya.

DESIGN

Prospective cohort study.

METHODS

From 1998 to 2012, HIV-negative FSWs were asked to return monthly for an interview regarding risk behavior and testing for sexually transmitted infections including HIV. We evaluated the association between community ART coverage and FSW's risk of becoming HIV infected using Cox proportional hazards models adjusted for potential confounding factors.

RESULTS

One thousand, four hundred and four FSWs contributed 4335 woman-years of follow-up, with 145 acquiring HIV infection (incidence 3.35/100 woman-years). The ART rollout began in 2003. By 2012, an estimated 52% of HIV-positive individuals were receiving treatment. Community ART coverage was inversely associated with HIV incidence (adjusted hazard ratio 0.77; 95% confidence interval 0.61-0.98; P = 0.03), suggesting that each 10% increase in coverage was associated with a 23% reduction in FSWs' risk of HIV acquisition. Community ART coverage had no impact on herpes simplex virus type-2 incidence (adjusted hazard ratio 0.97; 95% confidence interval 0.79-1.20; P = 0.8).

CONCLUSION

Increasing general population ART coverage was associated with lower HIV incidence in FSWs. The association with HIV incidence, but not herpes simplex virus type-2 incidence, suggests that the effect of community ART coverage may be specific to HIV. Interventions such as preexposure prophylaxis and antiretroviral-containing microbicides have produced disappointing results in HIV prevention trials with FSWs. These results suggest that FSWs' risk of acquiring HIV infection might be reduced through the indirect approach of increasing ART coverage in the community.

HIV acquisition during pregnancy and postpartum is associated with genital infections and partnership characteristics

OBJECTIVE

The objective of this study is to determine the risk and cofactors for HIV acquisition during pregnancy and postpartum.

DESIGN

A prospective cohort study

METHODS

: Pregnant women in western Kenya were enrolled if HIV seronegative at that visit or within 3 months. Serial HIV nucleic acid amplification tests (NAATs) were conducted at 1 to 3-month intervals to 9 months postpartum. Genital swabs were collected for detection of chlamydia and gonorrhoea at baseline, and for trichomonas, bacterial vaginosis and yeast at baseline and follow-up.

RESULTS

Among 1304 pregnant women, median age was 22 years, 78% were married for a median of 4 years, 66% reported knowing partner HIV status and 8% reported using condoms. Study retention was 98%. During 1235 person-years of follow-up, HIV incidence was 2.31/100 person-years [95% confidence interval (95% CI) 0.71-4.10]. Incident HIV was associated with syphilis (hazard ratio 9.18, 95% CI 2.15-39.3), chlamydia (hazard ratio 4.49, 95% CI 1.34-15.0), bacterial vaginosis (hazard ratio 2.91, 95% CI 1.25-6.76), yeast (hazard ratio 3.46, 95% CI 1.46-8.19), sexually transmitted infection (STI) history (hazard ratio 3.48, 95% CI 1.31-9.27), lifetime number of sex partners (hazard ratio 1.19, 95% CI 1.03-1.37), partner age discordance (hazard ratio 1.07 per year, 95% CI 1.02-1.13) and shorter marriage (hazard ratio 1.19 per year, 95% CI 1.03-1.38). No women with incident HIV reported an HIV-infected partner. In multivariate analyses, chlamydia, older partners and yeast infection remained significant; however, power was limited.

CONCLUSION

Pregnant and lactating women may not perceive HIV risk and rarely used condoms. Prevention and treatment of genital infections and risk stratification to identify women for pre-exposure prophylaxis (PrEP) could decrease HIV acquisition in pregnant/lactating women.

Changes in the contribution of genital tract infections to HIV acquisition among Kenyan high-risk women from 1993 to 2012

OBJECTIVE

The objective of this study was to understand temporal trends in the contribution of different genital tract infections to HIV incidence over 20 years of follow-up in a cohort of high-risk women.

DESIGN

A prospective cohort study.

METHODS

We performed monthly evaluations for HIV, vaginal yeast, bacterial vaginosis, Trichomonas vaginalis, Neisseria gonorrhoeae, nonspecific cervicitis, herpes simplex virus type two (HSV-2), genital ulcer disease (GUD) and genital warts. We used Cox regression to evaluate the association between sexually transmitted infections (STIs) and HIV acquisition over four time periods (1993-1997, 1998-2002, 2003-2007, 2008-2012). Models were adjusted for age, workplace, sexual risk behaviour, hormonal contraceptive use and other STIs. The resulting hazard ratios were used to calculate population attributable risk percentage (PAR%).

RESULTS

Between 1993 and 2012, 1964 women contributed 6135 person-years of follow-up. The overall PAR% for each infection was prevalent HSV-2 (48.3%), incident HSV-2 (4.5%), bacterial vaginosis (15.1%), intermediate microbiota (7.5%), vaginal yeast (6.4%), T. vaginalis (1.1%), N. gonorrhoeae (0.9%), nonspecific cervicitis (0.7%), GUD (0.8%) and genital warts (-0.2%). Across the four time periods, the PAR% for prevalent HSV-2 (40.4%, 61.8%, 58.4%, 48.3%) and bacterial vaginosis (17.1%, 19.5%, 14.7%, 17.1%) remained relatively high and had no significant trend for change over time. The PAR% for trichomoniasis, gonorrhoea, GUD and genital warts remained less than 3% across the four periods.

CONCLUSION

Bacterial vaginosis and HSV-2 have consistently been the largest contributors to HIV acquisition risk in the Mombasa Cohort over the past 20 years. Interventions that prevent these conditions would benefit women's health and could reduce their risk of becoming infected with HIV.

Changes in sexual risk behavior in the Mombasa cohort: 1993-2007

The Mombasa Cohort is an open cohort study following HIV-seronegative women reporting transactional sex. Established in 1993, the cohort provides regular HIV counseling and testing at monthly visits. Over time, HIV acquisition risk has declined steadily in this cohort. To evaluate whether this decline may reflect changes in sexual risk behavior, we investigated trends in condom use and partner numbers among women who participated in the Mombasa Cohort between 1993 and 2007. Multinomial logistic regression and generalized estimating equations were used to evaluate the association of calendar time and follow-up time with key risk behaviors, after adjustment for potential confounding factors. At enrollment visits by 1,844 women, the adjusted probability of never using condoms decreased over time, from 34.2% to 18.9%. Over 23,911 follow-up visits, the adjusted probabilities of reporting >2 partners decreased from 9.9% to 4.9% and inconsistent condom use decreased from 7.9% to 5.3% after ≥12 cohort visits. Important predictors of risk behavior were work venue, charging low fees for sex, and substance abuse. Women with a later sexual debut had less risky behavior. Although sexual risk has declined among women participating in the Mombasa Cohort, HIV acquisition continues to occur and interventions to promote and reinforce safer sex are clearly needed.

Incident HIV during pregnancy and postpartum and risk of mother-to-child HIV transmission: a systematic review and meta-analysis

BACKGROUND

Women may have persistent risk of HIV acquisition during pregnancy and postpartum. Estimating risk of HIV during these periods is important to inform optimal prevention approaches. We performed a systematic review and meta-analysis to estimate maternal HIV incidence during pregnancy/postpartum and to compare mother-to-child HIV transmission (MTCT) risk among women with incident versus chronic infection.

METHODS AND FINDINGS

We searched PubMed, Embase, and AIDS-related conference abstracts between January 1, 1980, and October 31, 2013, for articles and abstracts describing HIV acquisition during pregnancy/postpartum. The inclusion criterion was studies with data on recent HIV during pregnancy/postpartum. Random effects models were constructed to pool HIV incidence rates, cumulative HIV incidence, hazard ratios (HRs), or odds ratios (ORs) summarizing the association between pregnancy/postpartum status and HIV incidence, and MTCT risk and rates. Overall, 1,176 studies met the search criteria, of which 78 met the inclusion criterion, and 47 contributed data. Using data from 19 cohorts representing 22,803 total person-years, the pooled HIV incidence rate during pregnancy/postpartum was 3.8/100 person-years (95% CI 3.0-4.6): 4.7/100 person-years during pregnancy and 2.9/100 person-years postpartum (p = 0.18). Pooled cumulative HIV incidence was significantly higher in African than non-African countries (3.6% versus 0.3%, respectively; p<0.001). Risk of HIV was not significantly higher among pregnant (HR 1.3, 95% CI 0.5-2.1) or postpartum women (HR 1.1, 95% CI 0.6-1.6) than among non-pregnant/non-postpartum women in five studies with available data. In African cohorts, MTCT risk was significantly higher among women with incident versus chronic HIV infection in the postpartum period (OR 2.9, 95% CI 2.2-3.9) or in pregnancy/postpartum periods combined (OR 2.3, 95% CI 1.2-4.4). However, the small number of studies limited power to detect associations and sources of heterogeneity.

CONCLUSIONS

Pregnancy and the postpartum period are times of persistent HIV risk, at rates similar to "high risk" cohorts. MTCT risk was elevated among women with incident infections. Detection and prevention of incident HIV in pregnancy/postpartum should be prioritized, and is critical to decrease MTCT.

HIV-1 superinfection occurs less frequently than initial infection in a cohort of high-risk Kenyan women

HIV superinfection (reinfection) has been reported in several settings, but no study has been designed and powered to rigorously compare its incidence to that of initial infection. Determining whether HIV infection reduces the risk of superinfection is critical to understanding whether an immune response to natural HIV infection is protective. This study compares the incidence of initial infection and superinfection in a prospective seroincident cohort of high-risk women in Mombasa, Kenya. A next-generation sequencing-based pipeline was developed to screen 129 women for superinfection. Longitudinal plasma samples at <6 months, >2 years and one intervening time after initial HIV infection were analyzed. Amplicons in three genome regions were sequenced and a median of 901 sequences obtained per gene per timepoint. Phylogenetic evidence of polyphyly, confirmed by pairwise distance analysis, defined superinfection. Superinfection timing was determined by sequencing virus from intervening timepoints. These data were combined with published data from 17 additional women in the same cohort, totaling 146 women screened. Twenty-one cases of superinfection were identified for an estimated incidence rate of 2.61 per 100 person-years (pys). The incidence rate of initial infection among 1910 women in the same cohort was 5.75 per 100 pys. Andersen-Gill proportional hazards models were used to compare incidences, adjusting for covariates known to influence HIV susceptibility in this cohort. Superinfection incidence was significantly lower than initial infection incidence, with a hazard ratio of 0.47 (CI 0.29-0.75, p = 0.0019). This lower incidence of superinfection was only observed >6 months after initial infection. This is the first adequately powered study to report that HIV infection reduces the risk of reinfection, raising the possibility that immune responses to natural infection are partially protective. The observation that superinfection risk changes with time implies a window of protection that coincides with the maturation of HIV-specific immunity.

Anticipated changes in sexual risk behaviour following vaccination with a low-efficacy HIV vaccine: survey results from a South African township

We assessed the potential for anticipated changes in sexual risk-taking behaviour following hypothetical administration of a low-efficacy preventive HIV vaccine. We developed a survey and collected self-reported data from 158 HIV-negative volunteers in a cohort undergoing prescreening for Phase I/II HIV vaccine trials in Soweto. Overall, 22% reported they might use condoms less frequently; 9% reported that they might increase their frequency of sex with casual/anonymous partners; and 55% reported their sexual partners might want to use condoms less frequently knowing they were vaccinated. Multivariate analyses revealed that anticipated decrease in condom use was predicted by poor comprehension and by young age. Individuals may increase their risk-taking behaviour knowing that a vaccine would provide only incomplete protection against HIV transmission. In HIV vaccine trials and future vaccination programmes, education and risk-reduction counselling will be needed for vaccinated individuals and their partners, and mass media education campaigns may be necessary.

Analysis of duration of risk behaviour for key populations: a literature review

Background

The objective of this paper is to review literature in order to calculate regional estimates of the average duration of time individuals maintain a specific high-risk behaviour.

Methods

The review targeted the key populations of female sex workers (FSW), male clients of female sex workers (MCFSW), people who inject drugs (injecting drug users (IDU)) and high-risk men who have sex with men (MSM). To be included in the review the study had to provide information on (1) the time a person spent at risk until death or cessation of the risk behaviour, (2) the percentage of the sample who initiated the risk behaviour in less than a year or (3) the mean or median duration of the behaviour from a representative sample.

Results

49 papers were found for the FSW population describing the period of time FSW stay in sex work to be between 2.9 years (Asia) and 12 years (Latin America). Eight papers were found for MCFSW showing the duration of the risk behaviour in this category varying from 4.6 years in Africa to 32 years in Asia. 86 papers were reviewed for the population of IDU showing that the average time a person injects illegal drugs varies from 5.6 years (Africa) to 21 years (South America). No information was found for duration of high-risk behaviour among MSM; instead, the definitions found in the literature for high- and low-risk behaviour among MSM were described.

Conclusions

There is high variability of estimates of duration of high-risk behaviours at regional level. More research is needed to inform models and prevention programmes on the average duration of time individuals maintain a specific high-risk behaviour.

Alcohol use, mycoplasma genitalium, and other STIs associated With HIV incidence among women at high risk in Kampala, Uganda

BACKGROUND

In 2008, the first clinic for women involved in high-risk sexual behavior was established in Kampala, offering targeted HIV prevention. This article describes rates, determinants, and trends of HIV incidence over 3 years.

METHODS

A total of 1027 women at high risk were enrolled into a closed cohort. At 3-monthly visits, data were collected on sociodemographic variables and risk behavior; biological samples were tested for HIV and other reproductive tract infections/sexually transmitted infections (RTI/STIs). Hazard ratios for HIV incidence were estimated using Cox proportional hazards regression among the 646 women HIV negative at enrolment.

RESULTS

HIV incidence was 3.66/100 person-years (pyr) and declined from 6.80/100 pyr in the first calendar year to 2.24/100 pyr and 2.53/100 pyr in the following years (P trend = 0.003). Sociodemographic and behavioral factors independently associated with HIV incidence were younger age, younger age at first sex, alcohol use (including frequency of use and binge drinking), number of paying clients in the past month, inconsistent condom use with clients, and not being pregnant. HIV incidence was also independently associated with Mycoplasma genitalium infection at enrolment [adjusted hazard ratio (aHR) = 2.28, 95% confidence interval (CI): 1.15 to 4.52] and with Neisseria gonorrhoeae (aHR = 5.91, 95% CI: 3.04 to 11.49) and Trichomonas vaginalis infections at the most recent visit (aHR = 2.72, 95% CI: 1.27 to 5.84). The population attributable fractions of HIV incidence for alcohol use was 63.5% (95% CI: 6.5 to 85.8) and for treatable RTI/STIs was 70.0% (95% CI: 18.8 to 87.5).

CONCLUSIONS

Alcohol use and STIs remain important risk factors for HIV acquisition, which call for more intensive control measures in women at high risk. Further longitudinal studies are needed to confirm the association between M. genitalium and HIV acquisition.

Risk factors for HIV-1 infection in a longitudinal, prospective cohort of adults from the Mbeya Region, Tanzania

BACKGROUND

To control the global HIV epidemic, targeted interventions to reduce the incidence of HIV infections are urgently needed until an effective HIV vaccine is available. This study describes HIV-1 incidence and associated risk factors in a general population cohort of adults from Mbeya region, Tanzania, who participated in a vaccine preparedness study.

METHODS

We conducted a closed prospective cohort study with 6-monthly follow-up from 2002 to 2006 enrolling adults from the general population. HIV-1 incidence and risk factors for HIV-1 acquisition were analyzed using Cox regression.

RESULTS

We observed 2578 seronegative participants for a mean period of 3.06 person years (PY) (7471 PY in total). Overall HIV-1 incidence was 1.35 per 100 PY (95% confidence interval [CI], 1.10-1.64/100 PY). The highest overall HIV-1 incidence was found in females from Itende village (1.55 per 100 PY; 95% CI, 0.99-2.30/100 PY); the highest age-specific incidence was observed in semiurban males aged 30 to 34 years (2.75 per 100 PY; 95% CI, 0.75-7.04). HIV-1 acquisition was independently associated with female gender (hazard ratio [HR], 1.64; 95% CI, 1.05-2.57), younger age at enrollment (age 18-19 versus 35-39 years: HR, 0.29; 95% CI, 0.11-0.75), alcohol consumption (almost daily versus none: HR, 2.01; 95% CI, 1.00-4.07), education level (secondary school versus none: HR, 0.39; 95% CI, 0.17-0.89), and number of lifetime sex partners (more than five versus one: HR, 2.22; 95% CI, 1.13-4.36).

CONCLUSIONS

A high incidence of HIV was observed in this cohort, and incident infection was strongly associated with young age, alcohol consumption, low school education level, and number of sex partners. Targeted interventions are needed to address the elevated risk associated with these factors.

Cofactors for HIV-1 incidence during pregnancy and postpartum period

OBJECTIVES

to estimate HIV-1 incidence and cofactors for HIV-1 incidence during pregnancy and postpartum.

DESIGN

retrospective study among women who were HIV seronegative during pregnancy.

METHODS

mothers accompanying their infants for routine 6-week immunizations at 6 maternal child health clinics in Nairobi and Western Kenya were tested for HIV-1 after completing a questionnaire that included assessment of sociodemographics, obstetric history and HIV-1 risk perception.

RESULTS

of 2,135 mothers who had tested HIV-1 seronegative antenatally, 2,035 (95.3%) accepted HIV-1 re-testing at 6 weeks postpartum. Of these, 53 (2.6%) were HIV-1 seropositive yielding an estimated HIV-1 incidence of 6.8 (95% CI: 5.1-8.8) per 100 woman-years). Mothers who seroconverted were more likely to be employed (45.3% vs 29.0%, p=0.01), married (96.2 vs 86.6%, p=0.04) and from a higher HIV-1 prevalence region (60.4% in Western Kenya vs 28.8% in Nairobi, p<0.001). Among married women, those in polygamous relationship were significantly more likely to seroconvert (19.6% vs 6.7%, p<0.001). In multivariate analysis, region and employment independently predicted seroconversion.

CONCLUSIONS

repeat HIV-1 testing in early postpartum was highly acceptable and resulted in detection of substantial HIV-1 incidence during pregnancy and postpartum period. Within prevention of mother-to-child HIV-1 transmission programs strategic approaches to prevent maternal HIV-1 acquisition during pregnancy are urgently needed.

The quest for a T cell-based immune correlate of protection against HIV: a story of trials and errors

Even before the partial success of a preventive HIV vaccine in a recent Phase III clinical trial, there had been an active research effort to determine one or more immune correlates of protection for HIV infection. This effort has been hampered by the lack of natural protective immunity against HIV. As a result, most of the studies have focused on long-term non-progressive infection or other clinical situations, none of which fully recapitulates protective immunity against HIV. Although this effort has been successful in defining characteristics of T cells in acute and non-progressive HIV infection, and has therefore greatly expanded our knowledge of the immunopathogenesis of AIDS, its success in defining immune correlates of protection is less clear. In this Opinion article we offer a perspective on how successful this effort has been in defining immune correlates of protection that have been, or will be, of use in the development of an HIV vaccine. Our view is that investing in an iterative approach to human vaccine efficacy trials of sufficient size and sampling frequency will improve the likelihood that an immune correlate of vaccine protection will be defined.

Commercial sexual practices before and after legalization in Australia

The nature of sex work changes over time for many reasons. In recent decades around the world, there has been movement toward legalization and control of sex economies. Studies of the possible impact of legalization mainly have focused on sexually transmitted infections and violence, with little attention to change in the diversity of sexual services provided. This study examined the practices of sex workers before and after legalization of prostitution. Cross-sectional surveys of comparable samples of female sex workers were conducted in 1991 (N = 200, aged 16-46 years) and 2003 (N = 247, aged 18-57 years) in Queensland, Australia, spanning a period of major change in regulation of the local industry. In 2003, male clients at brothels and private sole operators (N = 161; aged 19-72 years) were also interviewed. Over time, there was a clear increase in the provision of "exotic" sexual services, including bondage and discipline, submission, fantasy, use of sex toys, golden showers, fisting, and lesbian double acts, while "traditional" services mostly remained at similar levels (with substantial decrease in oral sex without a condom). Based on comparisons of self-reports of clients and workers, the demand for anal intercourse, anal play, and urination during sex apparently exceeded supply, especially in licensed brothels. Within this population, legalization of sex work coincided with a substantial increase in diversity of services, but it appears that in the regulated working environments, clients who prefer high risk practices might not dictate what is available to them.

Pilot study assessing HIV vaccine trial readiness among female sex workers, injection and non-injection drug users, and men who have sex with men in Spain

The purpose of this study was to assess HIV risk and willingness to participate in HIV vaccine trials in three high risk populations in Spain. Eight hundred and forty-four participants, comprising female sex workers, injection and non-injection drug users (IDUs and NIDUs, respectively), and men who have sex with men were tested for HIV and surveyed for risk and willingness to participate in future preventive HIV vaccine trials. HIV seroprevalence was 3.8% (95% CI: 2-11). HIV infection was associated with transgender identification, IDU in the past year, and sex with an IDU or other drug-using partner. The majority (82%) expressed their willingness to participate in HIV vaccine trials. Substantial sexual and parenteral risk in all groups and concomitant willingness to participate in vaccine trials was found, particularly among women and IDUs. Additional longitudinal cohort studies in Spain are needed to plan future vaccine efficacy trials.

Are women who work in bars, guesthouses and similar facilities a suitable study population for vaginal microbicide trials in Africa?

BACKGROUND

A feasibility study was conducted to investigate whether an occupational at-risk cohort of women in Mwanza, Tanzania are a suitable study population for future phase III vaginal microbicide trials.

METHODOLOGY/PRINCIPAL FINDINGS

1573 women aged 16-54 y working in traditional and modern bars, restaurants, hotels, guesthouses or as local food-handlers were enrolled at community-based reproductive health clinics, provided specimens for HIV/STI and pregnancy testing, and asked to attend three-monthly clinical follow-up visits for 12-months. HIV positive and negative women were eligible to enter the feasibility study and to receive free reproductive health services at any time. HIV prevalence at baseline was 26.5% (417/1573). HIV incidence among 1156 sero-negative women attending at baseline was 2.9/100PYs. Among 1020 HIV sero-negative, non-pregnant women, HIV incidence was 2.0/100PYs, HSV-2 incidence 12.7/100PYs and pregnancy rate 17.8/100PYs. Retention at three-months was 76.3% (778/1020). Among 771 HIV sero-negative, non-pregnant women attending at three-months, subsequent follow-up at 6, 9 and 12-months was 83.7%, 79.6%, and 72.1% respectively. Older women, those who had not moved home or changed their place of work in the last year, and women working in traditional bars or as local food handlers had the highest re-attendance.

CONCLUSIONS/SIGNIFICANCE

Women working in food outlets and recreational facilities in Tanzania and other parts of Africa may be a suitable study population for microbicide and other HIV prevention trials. Effective locally-appropriate strategies to address high pregnancy rates and early losses to follow-up are essential to minimise risk to clinical trials in these settings.

HIV-1 incidence rates and risk factors in agricultural workers and dependents in rural Kenya: 36-month follow-up of the Kericho HIV cohort study

BACKGROUND

Incidence data from prospective cohort studies using rigorous laboratory methods are important in designing and evaluating HIV vaccine and therapeutic clinical trials and health care programs. We report 36-month HIV-1 incidence rates and demographic and psychosocial risks from the Kericho cohort in rural Kenya's southern Rift Valley Province.

METHODS

Thirty-six month, prospective, closed, observational cohort study of adult plantation workers and dependents followed biannually. HIV-1 incidence rates per 100 person-years (py) were calculated, and Cox regression analyses were used to estimate hazards ratios (HR) associated with seroconversion.

RESULTS

Two thousand four hundred volunteers (mean age +/- SD = 30.1 +/- 8.5 years; 36.5% women) participated. Twenty-nine new HIV cases were identified in year 1 of follow-up, which increased to cumulative totals of 49 and 63 cases in years 2 and 3, respectively. The corresponding 1-, 2-, and 3-year incidence rates were 1.41 [95% confidence interval (CI) = 0.95-2.02], 1.16 (95% CI = 0.86-1.54), and 1.00 (95% CI = 0.77-1.28) per 100 py. Risk factors associated with HIV seroconversion included the following: of the Luo tribe (HR = 3.31; 95% CI = 1.65-6.63), marriage more than once (HR = 2.83; 95% CI = 1.20-6.69), self-reported male circumcision (HR = 0.32; 95% CI = 0.17-0.60), history of sexually transmitted infection (HR = 2.40; 95% CI = 1.09-5.26), history of substance abuse during sex (HR = 2.44; 95% CI = 1.16-5.13), and history of transactional sex (HR = 3.30; 95% CI = 1.79-6.09).

CONCLUSIONS

HIV-1 incidence rates were relatively low in adult plantation workers and dependents in rural Kenya. Cohorts including higher risk populations (eg, commercial sex workers) warrant consideration for regional HIV preventive vaccine trials. Even low incidence, well-described cohorts generate valuable epidemiological clinical trial data.

Treatment with antiretroviral therapy is not associated with increased sexual risk behavior in Kenyan female sex workers

OBJECTIVE

The objective of this study was to test the hypothesis that sexual risk behavior would increase following initiation of antiretroviral therapy (ART) in Kenyan female sex workers (FSWs).

DESIGN

Prospective cohort study.

SETTING

FSW cohort in Mombasa, Kenya, 1993-2008.

SUBJECTS

Eight hundred and ninety-eight women contributed HIV-1-seropositive follow-up visits, of whom 129 initiated ART.

INTERVENTION

Beginning in March 2004, ART was provided to women qualifying for treatment according to Kenyan National Guidelines. Participants received sexual risk reduction education and free condoms at every visit.

MAIN OUTCOME MEASURES

Main outcome measures included unprotected intercourse, abstinence, 100% condom use, number of sexual partners, and frequency of sex. Outcomes were evaluated at monthly follow-up visits using a 1-week recall interval.

RESULTS

Compared with non-ART-exposed follow-up, visits following ART initiation were not associated with an increase in unprotected sex [adjusted odds ratio (AOR) 0.86, 95% confidence interval (CI) 0.62-1.19, P = 0.4]. There was a nonsignificant decrease in abstinence (AOR 0.81, 95% CI 0.65-1.01, P = 0.07), which was offset by a substantial increase in 100% condom use (AOR 1.54, 95% CI 1.07-2.20, P = 0.02). Numbers of sex partners and frequency of sex were similar before versus after starting ART. A trend for decreased sexually transmitted infections following ART initiation provides additional support for the validity of the self-reported behavioral outcomes (AOR 0.67, 95% CI 0.44-1.02, P = 0.06).

CONCLUSION

In the setting of ongoing risk reduction education and provision of free condoms, initiation of ART was not associated with increased sexual risk behavior in this cohort of Kenyan FSWs.

Weighing the gold in the gold standard: challenges in HIV prevention research

OBJECTIVE(S)

Few HIV prevention interventions have been evaluated in randomized controlled trials (RCTs). We examined design, implementation, and contextual considerations that may limit detection of a positive or adverse effect in HIV prevention trials.

DESIGN

A systematic review of late phase RCTs for prevention of sexual transmission of HIV that randomly allocated intervention and comparison groups; evaluated interventions to prevent sexual transmission in nonpregnant populations; and reported HIV incidence as the primary or secondary outcome.

METHODS

PubMed/MEDLINE, other electronic databases, and electronic conference proceedings of recent HIV/AIDS-related conferences were searched to identify published or unpublished trials meeting the inclusion criteria. Descriptive, methodological, and contextual factors were abstracted from each trial.

RESULTS

The review included 37 HIV prevention RCTs reporting on 39 unique interventions. Only six RCTs, all evaluating biomedical interventions, demonstrated definitive effects on HIV incidence. Five of the six RCTs significantly reduced HIV infection: all three male circumcision trials, one trial of sexually transmitted infection treatment and care, and one vaccine trial. One microbicide trial of nonoxynol-9 gel produced adverse results. Lack of statistical power, poor adherence, and diluted versions of the intervention in comparison groups may have been important issues for the other trials that demonstrated 'flat' results.

CONCLUSION

Almost 90% of HIV prevention trials had 'flat' results, which may be attributable to trial design and/or implementation. The HIV prevention community must not only examine evidence from significant RCTs, but must also examine flat trials and address design and implementation issues that limit detection of an effect.

A systematic review of the quality of trials evaluating biomedical HIV prevention interventions shows that many lack power

PURPOSE

Several randomized, controlled trials (RCTs) have tested strategies to prevent sexual acquisition of HIV infection, but their quality has been variable. We aimed to identify, describe, and evaluate the quality of RCTs studying biomedical interventions to prevent HIV acquisition by sexual transmission.

METHOD

We conducted a systematic review to identify all RCTs evaluating the efficacy of biomedical HIV prevention interventions. We assessed seven generic and content-specific quality components important in HIV prevention trials, factors influencing study power, co-interventions provided, and trial ethics.

RESULTS

We identified 26 eligible RCTs. The median number of quality components judged to be in adequate or unclear was 3 (range 1-4) in 1992-1998, 3 (range 1-4) in 1999-2003, and 0 (range0-2) in 2004-2008 (p < .001). Common problems that may have biased results included low retention (median 84%), poor adherence to interventions requiring on going use (median < or =78%), and lower HIV incidence than expected a priori (in 8 of 11 trials where evaluable).

CONCLUSION

Reporting of trials of biomedical HIV prevention interventions has improved over time. However, quality improvement is needed in several key areas that influence study power, including participant retention, adherence to interventions, and estimation of expected HIV incidence.

The potential role of biomarkers in HIV preventive vaccine trials

BACKGROUND

Successful conduct of HIV vaccine efficacy trials entails identification and enrollment of at-risk populations, assessment of appropriate end points as measures of vaccine efficacy for prevention of HIV acquisition, and amelioration of disease course among infected vaccinees, as well as identification of potential confounders or effect modifiers. Although not invariably useful and bringing their own cost in terms of measurement and validation, a variety of biomarkers may aid at each stage of trial conduct.

METHODS

A review of selected articles, chosen based on quality, relevance of the biomarker to HIV vaccine trials, and availability of the publication, was conducted. The authors also drew experience from current trials and other planned or ongoing trials.

CONCLUSIONS

Biomarkers are available to assess HIV incidence in potential study populations, but care is needed in interpreting results of these assays. During trial conduct, sexually transmitted infections such as herpes simplex virus type 2 may act as effect modifiers on primary and secondary end points, including HIV incidence and set point viral load. The utility of sexually transmitted infection biomarkers will likely depend heavily on local epidemiology at clinical trial sites. Analyses from recent large HIV vaccine efficacy trials point to the complexities in interpreting trial results and underscore the potential utility of biomarkers in evaluating confounding and effect modification.

Effectiveness of interventions for the prevention of HIV and other sexually transmitted infections in female sex workers in resource poor setting: a systematic review

OBJECTIVE

To systematically review the evidence for effectiveness of HIV and sexually transmitted infection (STI) prevention interventions in female sex workers in resource poor settings.

METHOD

Published and unpublished studies were identified through electronic databases (Cochrane database, Medline, Embase, and Web of Science), hand searching and contacting experts. Randomized-controlled-trials and quasi-experimental studies were included if they were conducted in female sex workers from low and middle income settings; if the exposure was described; if the outcome was externally measurable, it was after the discovery of HIV, and if follow-up was longer than 6 months. A priori criteria were used to extract data. Meta-analysis was not performed due to the heterogeneity of studies.

RESULTS

Twenty-eight interventions were included. Despite methodological limitations, the evidence suggested that combining sexual risk reduction, condom promotion and improved access to STI treatment reduces HIV and STI acquisition in sex workers receiving the intervention. Strong evidence that regular STI screening or periodic treatment of STIs confers additional protection against HIV was lacking. It appears that structural interventions, policy change or empowerment of sex workers, reduce the prevalence of STIs and HIV.

CONCLUSION

Rigorous evaluation of HIV/STI prevention interventions in sex workers is challenging. There is some evidence for the efficacy of multi-component interventions, and/or structural interventions. The effect of these interventions on the wider population has rarely been evaluated.

HIV-1 infection in high risk men who have sex with men in Mombasa, Kenya

BACKGROUND

The role of homosexuality and anal sex practices in the African HIV -1 epidemic is not well described. We aimed to assess the risk factors for prevalent HIV-1 infection among men who have sex with men (MSM) to guide HIV-1 prevention efforts.

METHODS

Socio-behavioural characteristics, signs and symptoms of sexually transmitted diseases (STD), and serological evidence of HIV-1 were determined for 285 MSM at enrolment into a vaccine preparedness cohort study. We used multivariate logistic regression to assess risk factors for prevalent HIV-1 infection.

RESULTS

HIV-1 prevalence was 43.0% [49/114, 95% confidence interval (CI), 34-52%] for men who reported sex with men exclusively (MSME), and 12.3% (21/171, 95% CI, 7-17%) for men who reported sex with both men and women (MSMW). Eighty-six (75%) MSME and 69 (40%) MSMW reported recent receptive anal sex. Among 174 MSM sexually active in the last week, 44% reported no use of condoms with casual partners. In the previous 3 months, 210 MSM (74%) reported payment for sex, and most clients (93%) were local residents. Prevalent HIV-1 infection was associated with recent receptive anal sex [odds ratio (OR), 6.1; 95% CI, 2.4-16], exclusive sex with men (OR, 6.3; 95% CI, 2.3-17), and increasing age (OR, 1.1 per year; 95% CI, 1.04-1.12). Only four MSM reported injecting drug use.

CONCLUSIONS

The high prevalence of HIV-1 in Kenyan MSM is probably attributable to unprotected receptive anal sex. There is an urgent need for HIV-1 prevention programmes to deliver targeted risk-reduction interventions and STD services to MSM in Kenya.

Social and behavioral aspects of child and adolescent participation in HIV vaccine trials

Recent data indicate that the worldwide rate of HIV infection in adolescents is steadily increasing. Internationally, more than 7000 youths between 15 and 24 years of age are infected with HIV daily, resulting in more than 2.5 million new infections annually. Almost two thirds (1.7 million) of these new infections occur in Africa. Estimates in 2000 showed that the number of South Africans between 15 and 49 years of age infected with HIV was 4.7 million. This number equates to a prevalence rate of 15.4% in those younger than 20 years. Adolescents form an important target group not only for preventative efforts but also for HIV vaccine trials. This article focuses on the social and psychological factors that affect adolescent decision making by considering adolescent risk-taking behaviors, problems associated with predicting adolescent behavior, peer relationships and decision making, sexual disinhibition, and the role of family relationships in adolescent decision making.

HIV-1 acquisition and disease progression are associated with decreased high-risk sexual behaviour among Kenyan female sex workers

BACKGROUND

Changes in sexual risk behaviour may occur following HIV-1 infection.

OBJECTIVE

To test the hypothesis that HIV-1 seroconversion and disease progression are associated with changes in risk behaviours, using data from a cohort of Kenyan female sex workers (FSWs).

METHODS

HIV-1-seronegative FSWs were enrolled in a prospective cohort study of risk factors for HIV-1 acquisition. At monthly visits, standardized interviews were conducted to assess sexual risk behaviour and HIV-1 serologic testing was performed. Seroconverters were invited to continue with follow-up. Between 1993 and 2004 (when antiretroviral therapy was introduced in the cohort), 265 women seroconverted for HIV-1 (incidence 7.7/100 person-years) and were included in this analysis.

RESULTS

Unprotected intercourse was reported at 546/2037 (27%) pre-seroconversion visits versus 557/3732 (15%) post-seroconversion visits (P < 0.001). These findings remained significant after adjustment for potential confounding factors [adjusted odds ratio (AOR) 0.69; 95% confidence interval (CI), 0.55-0.86]. Compared with HIV-1-seronegative women, there was a progressive stepwise decrease in unprotected intercourse among HIV-1-seropositive women with CD4 cell counts > or = 500 (AOR, 0.93; 95% CI, 0.62-1.39), 200-499 (AOR, 0.58; 95% CI, 0.41-0.82) and < 200 cells/microl (AOR, 0.45; 95% CI, 0.25-0.82). Decreases in unprotected intercourse reflected increases in both abstinence and 100% condom use. Women also reported fewer partners and fewer episodes of intercourse after HIV-1 seroconversion.

CONCLUSIONS

HIV-1 seroconversion and disease progression were associated with decreases in sexual risk behaviour among Kenyan FSWs.

Pediatric HIV type 1 vaccine trial acceptability among mothers in Kenya

Vaccination of infants against human immunodeficiency virus type 1 (HIV-1) may prevent mother-to-child HIV-1 transmission. Successful trials and immunization efforts will depend on the willingness of individuals to participate in pediatric vaccine research and acceptance of infant HIV-1 vaccines. In a cross-sectional study, pregnant women presenting to a Nairobi antenatal clinic for routine care were interviewed regarding their attitudes toward participation in research studies and HIV-1 vaccine acceptability for their infants. Among 805 women, 782 (97%) reported they would vaccinate their infant against HIV-1 and 729 (91%) reported willingness to enroll their infant in a research study. However, only 644 (80%) would enroll their infants if HIV- 1 testing was required every 3 months and 513 (64%) would agree to HIV-1 vaccine trial participation. Reasons for not wanting to enroll in a pediatric HIV-1 vaccine trial included concerns about side effects (75%), partner objection (34%), and fear of discrimination (10%), HIV-1 acquisition (8%), or false-positive HIV-1 results (5%). The strongest correlate of pediatric vaccine trial participation was maternal willingness to be a vaccine trial participant herself; in univariate and multivariate models this was associated with a 17-fold increased likelihood of participation (HR 17.1; 95% CI 11.7-25; p < 0.001). We conclude from these results that immunizing infants against HIV-1 and participation in pediatric vaccine trials are generally acceptable to women at high risk for HIV-1 infection. It will be important to address barriers identified in this study and to include male partners when mobilizing communities for pediatric HIV-1 vaccine trials and immunization programs.

Decline in sexually transmitted infection prevalence and HIV incidence in female barworkers attending prevention and care services in Mbeya Region, Tanzania

OBJECTIVE

To assess trends in sexually transmitted infection (STI) prevalence and HIV incidence and associated factors in a cohort of female barworkers exposed to behavioural interventions and STI screening and treatment.

METHODS

An open cohort of 600 female barworkers in Mbeya Region, Tanzania was offered 3-monthly information and education sessions on HIV/STI and reproductive health, voluntary HIV counselling and testing and clinical health check-ups including STI syndromic management with simple STI laboratory support. Outcome assessments included HIV, herpes simplex virus type 2 (HSV-2) and syphilis serology, polymerase chain reaction for Neisseria gonorrhoeae, Chlamydia trachomatis and ulcerative STI, microscopy for Trichomonas vaginalis, Candida albicans and bacterial vaginosis and interviews on sociodemographic and behavioural characteristics.

RESULTS

Over a period of 30 months 600 barworkers were enrolled at the baseline examination round and 153 thereafter as replacements for losses to follow-up. At 3-monthly examinations the prevalence of gonorrhoea declined steadily from 22.2 to 6.8% (odds ratio for trend per quarter: 0.81; P < 0.001). The prevalence of all other STI/RTI, except for genital herpes and bacterial vaginosis, also decreased significantly. HIV incidence declined from 13.9/100 to 5.0/100 person-years over three consecutive 9-month periods. HIV incidence was significantly associated with genital ulcers and positive syphilis serology, but not with genital herpes or HSV-2 seropositivity.

CONCLUSION

A relatively simple intervention consisting of regular 3-monthly STI screening and syndromic management in combination with HIV/STI information and counselling sessions was well accepted and effective in reducing STI among barworkers. Such interventions should be implemented more widely in high-risk environments in sub-Saharan Africa.

Socio-behaviour challenges to phase III HIV vaccine trials in Sub-Saharan Africa

BACKGROUND

A number of countries in sub-Saharan Africa are preparing for HIV vaccine efficacy trials. Social and behavioural factors related to HIV transmission require examination in each setting where these trials are considered. As part of this, several countries have also recently begun preparatory research investigating relevant social and behavioural issues. There is a need for a review of the literature to help focus such research efforts in Sub-Saharan Africa.

OBJECTIVES

To examine key social and behavioural issues that may impact on the conduct of HIV vaccine efficacy trials in sub-Saharan Africa.

DESIGN

Literature review

METHODS

Major databases (PubMed, PsychInfo, EBSCOhost, and AIDSline) were searched for literature that discussed social and behavioural issues related to HIV vaccine trials. Three areas are highlighted as being particularly significant for HIV vaccine research: (1) willingness to participate in future HIV vaccine efficacy trials, (2) retention of participants in studies, and (3) sexual risk reporting during trials. For each of these topics, major findings from both developed and developing countries are described and avenues for further research are discussed.

RESULTS

There are few data from Sub-Saharan Africa regarding willingness to participate in HIV vaccine trials. Data on participant retention rates varies widely, and maintaining large cohorts of individuals within Phase III trials presents an important challenge. In addition, the possible impact of trial participation on sexual disinhibition, and response bias on sexual risk-reporting remain as issues for HIV vaccine trials in African contexts.

CONCLUSION

Social and behavioural research forms an important part of preparations for HIV vaccine efficacy trials, and there is a clear need for more research of this type in Sub-Saharan Africa. Innovative approaches are required to address issues such as willingness to participate in vaccine research, participant retention during efficacy trials, and the accurate reporting by participants of sexual risk behaviours.

The epidemiological contribution to the preparation of field trials for HIV and STI vaccines: objectives and methods of feasibility studies

Feasibility studies are an important component of preparations for efficacy field trials of vaccine candidates, but represent a neglected area in clinical trial literature. These studies are designed to identify cohorts of higher-risk individuals with sufficiently high incidence to support a vaccine trial; to determine the readiness of these individuals to participate in a trial; to develop cost-effective recruitment and retention strategies, educational methods that ensure ethical informed consent, and instruments that accurately assess risk behaviours; to measure incidence rates over time and the effect of risk reduction interventions on incidence; to contribute estimates of incidence and loss to follow-up rates to sample size calculations; to assess the level of acceptability of a future efficacious vaccine in the target population and, in the case of several viruses, to identify circulating subtypes. Feasibility study methods have been largely developed in the context of HIV, but may also be used in the preparation of preventive intervention trials for other STI.

Methodological lessons from a cohort study of high risk women in Tanzania

OBJECTIVES

To describe the development, characteristics, and follow up of a high risk cohort of women in Tanzania. Differences in social background and sexual behaviour of women working in traditional and modern alcohol selling workplaces are shown.

METHODS

Data from questionnaires four months before the enrollment of the cohort, at enrollment, and at 32 months were compared. Key informant interviews, social mapping exercises, and focus group discussions were held before the start of the cohort.

RESULTS

In the absence of organised prostitution, two different groups of women with high risk exposure were identified during the baseline survey: female workers in modern alcohol selling places such as bars, guesthouses, and restaurants (barmaids) and in traditional places (local brew sellers). Overall, the population had a mean age of 27.7 years with barmaids tending to be younger (24.3 years) than local brew sellers (34.2 years). The main duration of stay in the current workplace was 2.1 years (barmaids 0.9 years; local brew sellers 4.1 years). Barmaids were more likely to have paying casual sex partners than local brew sellers and used condoms more regularly. Local brew sellers tend to be more stable with only 10% lost to follow up after 32 months compared with 24.4% of the bar workers.

CONCLUSIONS

Preliminary work revealed major differences in characteristics and behaviour between women working in modern and traditional alcohol selling outlets. Thorough preparation of the study, close monitoring of the cohort, and provision of selected benefits resulted in high retention rates over a 32 month project in a highly mobile population.

Social, cultural and sexual behavioral determinants of observed decline in HIV infection trends: lessons from the Kagera Region, Tanzania

This paper is a follow-up of earlier findings by the Kagera AIDS Research Project (KARP), which documented declining trends in the prevalence and incidence of HIV infection in the Kagera region of Tanzania. The paper examines socio-cultural and sexual behavioral changes as possible determinants of the observed declining trends in Bukoba, the largest urban area of the region. The study used in-depth interviews, focus group discussions, field observations and ethnographic assessments to collect the required data. The findings suggest that since the initial years of the epidemic there have been significant changes in sexual behaviors, norms, values, and customs that are considered high-risk for HIV transmission. The findings show an increase in condom use, abstinence, zero grazing (sticking to one sexual partner) and uptake of voluntary HIV testing while traditional practices such as polygamy, widow inheritance, excessive alcohol consumption, and sexual networking are declining. We suggest that these changes are partly a result of the severity of the epidemic itself in the study area, and interventions that have been carried out in this area since 1987. The major interventions have included health education, the distribution of condoms, AIDS education in schools, voluntary HIV counseling and testing. These are encouraging findings that give hope and we believe that other places within Tanzania and other countries experiencing a severe AIDS crisis have much to learn from this experience. However, changes in norms and behavior are vulnerable; people in Kagera are still at risk and there is a need for continued intervention together with monitoring of the direction of the epidemic.

Determinants of Enrollment in a Preventive HIV Vaccine Trial

OBJECTIVE

To compare hypothetical and actual willingness to enroll in a preventive HIV vaccine trial and identify factors affecting enrollment.

METHODS

Participants previously enrolled in an HIV vaccine preparedness study (VPS) in 8 US cities were invited to be screened for a phase 2 HIV vaccine trial. Demographic and risk characteristics of those enrolling, ineligible, and refusing enrollment were compared using the chi2 or Fisher exact test. Multivariable logistic models were used to identify independent predictors of refusal.

RESULTS

Of 2531 high-risk HIV-uninfected former VPS participants contacted for the vaccine trial, 13% enrolled, 34% were ineligible, and 53% refused enrollment. Only 20% of those stating hypothetical willingness during the VPS actually enrolled in this vaccine trial. In multivariate analysis, refusal was higher among African Americans and lower in persons >40 years of age, those attending college, and those with > or =5 partners in the prior 6 months. All racial ethnic groups cited concerns about vaccine-induced seropositivity; African Americans also cited mistrust of government and safety concerns as barriers to enrollment.

CONCLUSIONS

Steps can be taken to minimize potential social harms and to mobilize diverse communities to enroll in trials. Statements of hypothetical willingness to participate in future trials may overestimate true enrollment.

Prevalence of HIV and other sexually transmitted infections, and risk behaviours in unregistered sex workers in Dakar, Senegal

OBJECTIVES

To estimate the prevalence rates of HIV and other sexually transmitted infections (STI) among unregistered sex workers, and to describe their sociodemographic characteristics and sexual behaviours, and the reasons why they were not officially registered as sex workers, in order to design specific public health interventions.

METHODS

A one-stage cluster-sample survey was conducted in Dakar in 2000. Unregistered sex workers were interviewed in randomly selected establishments (official and clandestine bars, brothels and nightclubs), and blood, endocervical and vaginal samples were collected for laboratory diagnosis.

RESULTS

A total of 390 women with a median age of 29 years were recruited. One-seventh of them were under the legal age for prostitution in Senegal (21 years). The median length of prostitution was 24 months and 73.5% of the women stated regular prostitution. Three-quarters of the women were found to have markers for at least one infection. The prevalence rates were as follows: HIV-1, 6.0%; HIV-2, 3.6%; HIV-1+2, 0.4%; syphilis, 23.8%; gonorrhea, 22.0%; chlamydial infection, 20.0%; trichomoniasis, 22.4%; candidiasis, 19.0%; and bacterial vaginosis, 28.8%. The main reported reason for non-registration was ignorance of the legal system and its procedures (19.4%); 18.9% of the women refused to register. One-third of the women reported that their clients used condoms inconsistently or never.

CONCLUSION

This survey suggests that a multidimensional public health response is needed in Senegal, comprising legal information, downwards revision of the legal age for prostitution, and specific medical follow-up based on education, condom promotion and management of STI for non-registered sex workers.

HIV-1 epidemic trends in rural south-west Uganda over a 10-year period

The objective of this study was to examine the epidemic trends of HIV-1 infection in a rural population cohort in Uganda followed for 10 years. The methods used were to assess incidence and prevalence trends in adults in this longitudinal cohort study. The results showed that incidence of infection has fallen significantly in all adults, and separately in males, females, young adults and older adults over the course of the study period. There was also a reduction in prevalence, especially in young men and women. There was some evidence of a cohort effect in women. The conclusions are that this study provides the first evidence of a falling incidence in a rural general population in Africa. This was an observational cohort exposed to national health education messages, giving hope that similar campaigns elsewhere in Africa could be used effectively in efforts to control the HIV epidemic.

Declining HIV-1 incidence and associated prevalence over 10 years in a rural population in south-west Uganda: a cohort study

BACKGROUND

In Uganda, there have been encouraging reports of reductions in HIV-1 prevalence but not in incidence, which is the most reliable measure of epidemic trends. We describe HIV-1 incidence and prevalence trends in a rural population-based cohort between 1989 and 1999.

METHODS

We surveyed the adult population of 15 neighbouring villages for HIV-1 infection using annual censuses, questionnaires, and serological surveys. We report crude annual incidence rates by calendar year and prevalence by survey round.

FINDINGS

6566 HIV-1 seronegative adults were bled two or more times between January, 1990, and December, 1999, contributing 31984 person years at risk (PYAR) and 190 seroconversions. HIV-1 incidence fell from 8.0 to 5.2 per 1000 PYAR between 1990 and 1999 (p=0.002, chi(2) for trend). Significant sex-specific and age-group-specific reductions in incidence were evident. Incidence was 37% lower for 1995-99 than for 1990-94 (p=0.002, t-test). On average, 4642 adult residents had a definite HIV-1 serostatus at each yearly survey round. HIV-1 prevalence fell significantly between the first and tenth annual survey rounds (p=0.03, chi(2) for trend), especially among men aged 20-24 years (6.5% to 2.2%) and 25-29 years (15.2% to 10.9%) and women aged 13-19 years (2.8% to 0.9%) and 20-24 years (19.3% to 10.1%) (all p<0.001, chi(2) for trend).

INTERPRETATION

Our findings of a significant drop in adult HIV-1 incidence in rural Ugandans give hope to AIDS control programmes elsewhere in sub-Saharan Africa where rates of HIV-1 infection remain high.

Reduced HIV risk-taking and low HIV incidence after enrollment and risk-reduction counseling in a sexually transmitted disease prevention trial in Nairobi, Kenya

There is an urgent need in sub-Saharan Africa to develop more effective methods of HIV prevention, including improved strategies of sexually transmitted infection (STI) prevention or an HIV vaccine. The efficacy of these strategies may be tested through clinical trials within cohorts at high risk for STI and HIV, such as female commercial sex workers. For ethical reasons, standard HIV prevention services, including access to free condoms, risk-reduction counseling, and STI therapy, will generally be offered to all study subjects. Because study subjects would often not otherwise have access to these prevention services, it is possible that enrollment in such clinical trials will itself reduce incidence rates of STI and HIV below expected levels, reducing the power to test the efficacy of the randomized intervention. We show that the provision of standard HIV prevention services as part of a randomized STI/HIV prevention trial is temporally associated with a dramatic reduction in sexual risk-taking, and that this reduction is directly associated with reduced STI incidence. This finding should be considered in the design of clinical trials with an endpoint of HIV incidence, in particular HIV preventive vaccine trials.

Hormonal contraception and risk of sexually transmitted disease acquisition: results from a prospective study

OBJECTIVES

To examine the relationship between use of oral contraceptive pills or depot medroxyprogesterone acetate and sexually transmitted disease acquisition.

STUDY DESIGN

Prospective cohort included 948 Kenyan prostitutes. Multivariate Andersen-Gill proportional hazards models were constructed, adjusting for sexual behavioral and demographic variables.

RESULTS

When compared with women who were using no contraception, users of oral contraceptive pills were at increased risk for acquisition of chlamydia (hazard ratio, 1.8; 95% confidence interval, 1.1-2.9) and vaginal candidiasis (hazard ratio, 1.5; 95% confidence interval, 1.2-1.9) and at decreased risk for bacterial vaginosis (hazard ratio, 0.8; 95% confidence interval, 0.7-1.0). Women using depot medroxyprogesterone acetate had significantly increased risk of chlamydia infection (hazard ratio, 1.6; 95% confidence interval, 1.1-2.4) and significantly decreased risk of bacterial vaginosis (hazard ratio, 0.7; 95% confidence interval, 0.5-0.8), trichomoniasis (hazard ratio, 0.6; 95% confidence interval, 0.4-1.0), and pelvic inflammatory disease (hazard ratio, 0.4; 95% confidence interval, 0.2-0.7). Consistent condom use was associated with significantly decreased risk of gonorrhea, chlamydia, genital ulcer disease, bacterial vaginosis, and pelvic inflammatory disease.

CONCLUSIONS

The use of oral or injectable hormonal contraception altered susceptibility to sexually transmitted diseases, which may in turn influence transmission of human immunodeficiency virus type 1. Consistent condom use was protective with regards to sexually transmitted disease and should be encouraged for the prevention of sexually transmitted disease and human immunodeficiency virus type 1 among women who use hormonal contraception.