The contribution of STIs to the sexual transmission of HIV

Department of Infectious Disease Epidemiology, Imperial College, London, UK.
Current opinion in HIV and AIDS (Impact Factor: 4.68). 07/2010; 5(4):305-10. DOI: 10.1097/COH.0b013e32833a8844
Source: PubMed


We review recent evidence about the link between sexually transmitted infections (STI) and HIV transmission and consider implications for control programmes.
New studies and meta-analyses confirm the association of HIV acquisition and transmission with recent STIs, although there is considerable heterogeneity between organisms and populations. Much of the recent evidence relates to herpes simplex virus type 2 (HSV-2), for which the population-attributable risk percentage (PAR%) for HSV-2 is between 25 and 35 in Africa. Mathematical models show how transmission attributable to STI varies with HIV epidemic phase, and HSV-2 becomes increasingly important as the epidemic matures. HSV-2 suppressive therapy reduces HIV concentrations in plasma and the genital tract in people coinfected with HSV-2, in part due to direct inhibition of HIV reverse transcriptase. Recent trials of HSV-2 suppressive therapy have not shown an impact on the risk of HIV acquisition, nor in controlling transmission from dually infected people to their serodiscordant heterosexual partners.
Although there is a plausible link between STI and HIV risk, intervention studies continue to be disappointing. This fact does not disprove a causal link, but mechanisms of action and the design and implementation of interventions need to be better understood.

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Available from: Helen Ward, Jan 07, 2014
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    • "Safe services for medical male circumcision have been recommended for wide-scale roll-out by the World Health Organization (WHO) and the United Nations Programme on HIV/AIDS (UNAIDS), although progress in implementation in many countries has been slow [43,44]. HIV transmission is known to be facilitated by other sexually transmitted infections (STIs) [45]. One trial in Tanzania showed that improved STI treatment services reduced HIV incidence in the general population, although other trials of a variety of STI interventions in different epidemiological settings have failed to show an impact on HIV incidence [46]. "
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    ABSTRACT: Effective interventions to reduce HIV incidence in sub-Saharan Africa are urgently needed. Mathematical modelling and the HIV Prevention Trials Network (HPTN) 052 trial results suggest that universal HIV testing combined with immediate antiretroviral treatment (ART) should substantially reduce incidence and may eliminate HIV as a public health problem. We describe the rationale and design of a trial to evaluate this hypothesis. A rigorously-designed trial of universal testing and treatment (UTT) interventions is needed because: i) it is unknown whether these interventions can be delivered to scale with adequate uptake; ii) there are many uncertainties in the models such that the population-level impact of these interventions is unknown; and ii) there are potential adverse effects including sexual risk disinhibition, HIV-related stigma, over-burdening of health systems, poor adherence, toxicity, and drug resistance.In the HPTN 071 (PopART) trial, 21 communities in Zambia and South Africa (total population 1.2 m) will be randomly allocated to three arms. Arm A will receive the full PopART combination HIV prevention package including annual home-based HIV testing, promotion of medical male circumcision for HIV-negative men, and offer of immediate ART for those testing HIV-positive; Arm B will receive the full package except that ART initiation will follow current national guidelines; Arm C will receive standard of care. A Population Cohort of 2,500 adults will be randomly selected in each community and followed for 3 years to measure the primary outcome of HIV incidence. Based on model projections, the trial will be well-powered to detect predicted effects on HIV incidence and secondary outcomes. Trial results, combined with modelling and cost data, will provide short-term and long-term estimates of cost-effectiveness of UTT interventions. Importantly, the three-arm design will enable assessment of how much could be achieved by optimal delivery of current policies and the costs and benefits of extending this to UTT.Trial registration: NCT01900977.
    Trials 02/2014; 15(1):57. DOI:10.1186/1745-6215-15-57 · 1.73 Impact Factor
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    • "This is an alarming result because delayed treatment of STIs could have a profound impact on the health of the women both during their time as sex worker and in their future lives. Delay of or mistreatment for STIs has been shown to result in infertility, ectopic pregnancy, cervical cancer [14], and increased risk of acquiring HIV [15,16]. We found that two-thirds of those who did not seek treatment for RTI/STI symptoms were adolescents. "
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    ABSTRACT: Prompt, correct diagnosis and treatment with health information are essential components of reproductive tract infection (RTI) and sexually transmitted infection (STI) services. This study aims to describe care seeking behaviour and barriers to accessing RTI/STI services among female sex workers (FSWs) in Laos. A cross-sectional survey using closed and open-ended questions was performed in six districts along Road 9, traversing Savannakhet province from Thailand to Vietnam. In total, 407 FSWs were interviewed. The data were analyzed and presented descriptively. Multiple logistic regression analysis was applied to assess associations between respondents' background characteristics and care seeking behaviour. About half of the respondents (49%) were less than or equal to 19 years of age, and 50% had started or completed secondary school. Fifty-eight percent had been engaged in sex work for less than 1 year. Eighty-six percent of the respondents reported RTI/STI signs or symptoms currently or in the last 3 months but only two-thirds of those with symptoms sought treatment. Source of treatment for the last RTI/STI episode was the drop-in centre (53%) followed by a public hospital (23%), private clinic (12%), private pharmacy (9%), and herbalist (2%). The main barriers to service use were long waiting time, inconvenient location of the clinic, not knowing where to get the services needed, and negative attitudes among healthcare providers. Care seeking behaviour was associated with longer duration of sex work (OR = 2.6, 95%CI 1.52-5.36). Forty-four percent received health information from peer educators, 34% from fellow friends, 26% from a pimp, and 26% had received information from a healthcare provider during the visit. There were several barriers to accessing RTI/STI services and they were related to both structural and individual factors. Innovative STI service strategies to inform FSWs about the importance of early diagnosis and treatment should be established. Continuous training for STI service providers focusing on counseling skills and awareness of the sexual health care needs for FSWs is recommended in order to minimize the barriers experienced by FSWs in this particular setting.
    BMC Health Services Research 02/2012; 12(1):37. DOI:10.1186/1472-6963-12-37 · 1.71 Impact Factor
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    • "Herpes simplex virus (HSV), and especially HSV type 2, represents one of the most widely spread pathogen causing genital ulcer disease (GUD). Different studies have associated GUD aetiological agents in general, and HSV-2 in particular, with a higher risk to acquire and/or transmit HIV-1 infection [1-3]. A number of biological and molecular factors may explain this evidence. "
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    ABSTRACT: Epidemiological and clinical data indicate that genital ulcer disease (GUD) pathogens are associated with an increased risk of human immunodeficiency virus type 1 (HIV-1) acquisition and/or transmission. Among them, genital herpes simplex virus type 2 (HSV-2) seems to play a relevant role. Indeed, the ability of HSV-2 to induce massive infiltration at the genital level of cells which are potential targets for HIV-1 infection may represent one of the mechanisms involved in this process. Here we show that infection of human primary macrophages (MDMs) by HSV-2 results in an increase of CCR5 expression levels on cell surface and allows higher efficiency of MDMs to support entry of R5 HIV-1 strains. This finding could strengthen, at the molecular level, the evidence linking HSV-2 infection to an increased susceptibility to HIV-1 acquisition.
    Virology Journal 04/2011; 8(1):166. DOI:10.1186/1743-422X-8-166 · 2.18 Impact Factor
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