Identifying high STI prevalence populations in sub-Saharan Africa

Prevalence of curable sexually transmitted infections (STIs)- chlamydia, gonorrhea, syphilis and trichomoniasis -- among women aged 15 to 24 exceeds that of older women and similar-aged men in sub-Saharan Africa, according to research published this week in PLOS Medicine.

In one study, Elizabeth A. Torrone of the U.S. Centers for Disease Control and Prevention and colleagues performed a meta-analysis of individual participant data from 18 prior studies of HIV prevention. In the other, Suzanna C. Francis of the London School of Hygiene & Tropical Medicine and colleagues obtained new data within the structure of an established health surveillance project. The studies examine STI prevalence within age, sex, setting, and risk groups and further establish young women's sexual health as a priority issue in the region.

STIs are often asymptomatic, but can have devastating consequences including infertility and pelvic inflammatory disease. They can also increase the risk of HIV infection. Better information on STI prevalence is difficult to collect, particularly in sub-Saharan Africa, where inexpensive, feasible diagnostic tests are not available in most clinical settings.

To address this gap with available data, Torrone and colleagues conducted a meta-analysis using STI test results from 18 HIV prevention studies conducted in Eastern and Southern Africa between 1993 and 2011. In these studies, a total of more than 37,000 HIV-negative women were tested at baseline for curable STIs, the chronic, treatable STI herpes simplex virus type 2 (HSV-2), and the dysbiotic condition bacterial vaginosis (BV) to estimate the prevalence of STIs and BV by age, region and population-type.

Meanwhile, Francis and colleagues tested a pragmatic approach for collection of new data, by conducting nested STI surveillance within the Africa Health Research Institute (AHRI), a health and demographic surveillance site (HDSS) in rural KwaZulu-Natal, South Africa. Between October 2016 and January 2017, the researchers conducted home visits offering testing for STIs and BV to young people who were found at home and agreed to participate.

The studies estimated that, in most groups, more than 10% of young, female participants (aged 15-24) were infected with one or more curable STI. Torrone et al report that estimated prevalence of curable STIs was generally higher in women aged 15-24 than in women aged 25-49. Both studies estimate higher prevalence of HSV-2 and BV, compared with curable STI, in most groups; e.g., Torrone et al estimate HSV-2 prevalence of 39% [95% CI: 34.3%, 44.6%] and BV prevalence of 42.1% [35.6%, 49.0%] among women aged 15-24 in South African clinic and community-based populations. Francis et al also provide some of the first population data for STI burden in young men (chlamydia: 5% of men, 11% of women; HSV-2: 17% of men, 29% of women; BV: 42% of women). In Francis' et al's study, most (75%) of the curable STIs in women were asymptomatic.

The study heterogeneity observed in Torrone et al's meta-analysis, and the non-population-based sampling, underscore the need to strengthen surveillance efforts. The prevalence estimates gathered by Francis et al are also not fully representative; notably, successful contact with male and migrant individuals was low. However, the two studies provide broadly consistent findings, and demonstrate means of using existing data and established systems to obtain STI/BV prevalence estimates where routine surveillance is limited.

###

Research Article

Funding:

This work was funded by the UNDP-UNFPA-UNICEF-WHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), a cosponsored program executed by the World Health Organization (WHO), http://www.who.int/reproductivehealth/en/. CM received funding to conduct the analysis and had full access to all data in the study, and together with ET had final responsibility for the decision to submit for publication. SLG from WHO advised on study design and data analysis as required, helped with redrafts, and approved manuscript submission. The funders had no other role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests:

I have read the journal's policy and the authors of this manuscript have the following competing interests: RH receives royalties for textbook from Chapman and Hall and occasional attendance fees for serving on the MRC funding committee. KJL received funding from the World Health Organization during the course of this study. NL receives a stipend as a Specialty Consulting Editor for PLOS Medicine, serves on the journal's editorial board, and served as a Guest Editor on PLOS Medicine's Collection on the Prevention, Diagnosis, and Treatment of Sexually Transmitted Infections. SM reports grants, non-financial support, and other from Gilead Sciences PLC.

Citation:

Torrone EA, Morrison CS, Chen P-L, Kwok C, Francis SC, Hayes RJ, et al. (2018) Prevalence of sexually transmitted infections and bacterial vaginosis among women in sub-Saharan Africa: An individual participant data meta-analysis of 18 HIV prevention studies. PLoS Med 15(2): e1002511. https://doi.org/10.1371/journal.pmed.1002511

Author Affiliations:

Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
Global Health, Population and Nutrition, FHI 360, Durham, North Carolina, United States of America
Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom
Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
MRC Clinical Trials Unit, University College London, London, United Kingdom
Academic Unit of Primary Care and Population Sciences, University of Southampton, Southampton, United Kingdom
Department of Social Statistics and Demography, University of Southampton, Southampton, United Kingdom
Africa Health Research Institute, School of Nursing and Public Health, University of KwaZuluNatal, Durban, South Africa
Research Department of Epidemiology & Public Health, University College London, London, United Kingdom
Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
Mwanza Intervention Trials Unit, National Institute for Medical Research, Mwanza, Tanzania
Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland

In your coverage please use this URL to provide access to the freely available paper: http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002511

Research Article

Funding:

Financial support for this research was provided by ViiV Healthcare's Positive Action for Adolescents Programme; the Wellcome Trust with core funding for AHRI (082384/Z/07/Z) and NM receiving support (WT083495MA); the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013 under REA grant agreement MS receiving support (612216); and joint funding under the UK Medical Research Council (MRC)/ UK Department for International Development (DFID) Concordat agreement which is supported by the European Union under the EDCTP2 programme (reference MR/K012126/1) with SCF and KB receiving support (G0700837). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests:

The authors have declared that no competing interests exist.

Citation:

Francis SC, Mthiyane TN, Baisley K, Mchunu SL, Ferguson JB, Smit T, et al. (2018) Prevalence of sexually transmitted infections among young people in South Africa: A nested survey in a health and demographic surveillance site. PLoS Med 15(2): e1002512. https://doi.org/10.1371/journal.pmed.1002512

Author Affiliations:

MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom
Africa Health Research Institute, KwaZulu-Natal, South Africa
Centre for Maternal, Adolescent, Reproductive, and Child Health, London School of Hygiene & Tropical Medicine, London, United Kingdom
HIV/STI Reference Laboratory, Institute of Tropical Medicine, Antwerp, Belgium
Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, United Kingdom
Africa Health Research Institute, School of Nursing & Public Health, University of KwaZulu-Natal, KwaZulu-Natal, South Africa
Division of Infection and Immunity, University College London, London, United Kingdom
Academic Unit of Primary Care and Population Sciences, University of Southampton, Southampton, United Kingdom
Department of Social Statistics and Demography, University of Southampton, Southampton, United Kingdom
Research Department of Epidemiology & Public Health, University College London, London, United Kingdom
Institute for Global Health, University College London, London, United Kingdom

In your coverage please use this URL to provide access to the freely available paper:

http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002512

---

---