Prevalence of sexually transmitted infections among young people in South Africa: A nested survey in a health and demographic surveillance site

Abstract

Background: Sexually transmitted infections (STIs) and bacterial vaginosis (BV) are associated with increased transmission of HIV, and poor reproductive and sexual health. The burden of STIs/BV among young people is unknown in many high HIV prevalence settings. We conducted an acceptability, feasibility, and prevalence study of home-based sampling for STIs/BV among young men and women aged 15-24 years old in a health and demographic surveillance site (HDSS) in rural KwaZulu-Natal, South Africa.

Methods and findings: A total of 1,342 young people, stratified by age (15-19 and 20-24 years) and sex were selected from the HDSS sampling frame; 1,171/1,342 (87%) individuals had ≥1 attempted home visit between 4 October 2016 and 31 January 2017, of whom 790 (67%) were successfully contacted. Among the 645 who were contacted and eligible, 447 (69%) enrolled. Consenting/assenting participants were interviewed, and blood, self-collected urine (men), and vaginal swabs (women) were tested for herpes simplex virus type 2 (HSV-2), chlamydia, gonorrhoea, syphilis, trichomoniasis, and BV. Both men and women reported that sample collection was easy. Participants disagreed that sampling was painful; more than half of the participants disagreed that they felt anxious or embarrassed. The weighted prevalence of STIs/BV among men and women, respectively, was 5.3% and 11.2% for chlamydia, 1.5% and 1.8% for gonorrhoea, 0% and 0.4% for active syphilis, 0.6% and 4.6% for trichomoniasis, 16.8% and 28.7% for HSV-2, and 42.1% for BV (women only). Of the women with ≥1 curable STI, 75% reported no symptoms. Factors associated with STIs/BV included having older age, being female, and not being in school or working. Among those who participated in the 2016 HIV serosurvey, the prevalence of HIV was 5.6% among men and 19% among women. Feasibility was impacted by the short study duration and the difficulty finding men at home.

Conclusions: A high prevalence of STIs/BV was found in this rural setting with high HIV prevalence in South Africa. Most STIs and HIV infections were asymptomatic and would not have been identified or treated under national syndromic management guidelines. A nested STI/BV survey within a HDSS proved acceptable and feasible. This is a proof of concept for population-based STI surveillance in low- and middle-income countries that could be utilised in the evaluation of STI/HIV prevention and control programmes.

Fig 1. Flow diagram for enrolment in a population-based sexually transmitted infection survey among young people aged 15–24 years in rural Kwa-Zulu Natal.

¹Not visited: no visit was made to the household because the study ended. ²Not contacted: at least 1 visit was made to the household, but either a parent (if selected individual <18 years) or the individual was unavailable. ³Ineligible: individuals who were found to have out-migrated from the health and demographic surveillance site (N = 73 women and 53 men) or who were not capable of providing consent (N = 6 women and 4 men). ⁴Individuals who were interested in the study, but could not enrol because study ended.

Fig 2. Box and whisker plots of the acceptability of sampling in a population-based sexually transmitted infection/bacterial vaginosis survey among young people aged 15–24 years in rural KwaZulu-Natal.

The vertical line within the box indicates the median, the boundaries of the box indicate the interquartile range (25th and 75th percentiles), and the whiskers indicate values that are within 1.5 times the interquartile range above the 75th percentile, or 1.5 times the interquartile range below the 25th percentile. Values outside that range are plotted as individual points, e.g., the medians for (A) equal 0. (A) Ease of understanding the study and instructions, and the ease of sample collection. (B) Experience of self-collecting urine (males) or vaginal swabs (women)—positive items. (C) Experience of self-collecting urine (males) or vaginal swabs (women)—negative items.

Fig 3. Maps illustrating networks of health and demographic surveillance sites (HDSSs) at the global, regional, and national level.

(A) International Network for the Demographic Evaluation of Populations and their Health (INDEPTH Network), a network of 48 members and 7 associate members in 21 low- and middle-income countries in Africa, Asia, and Oceania conducting population-based surveillance of the health status of communities (modified from http://www.indepth-network.org/member-centres). (B) Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA Network), a network of 10 centres in sub-Saharan Africa conducting population-based HIV surveillance (modified from http://alpha.lshtm.ac.uk/partner-study-institutions/). (C) South African Population Research Infrastructure Network (SAPRIN), an expanding network of HDSSs in South Africa (modified from http://saprin.mrc.ac.za/nodes.html). AHRI, Africa Health Research Institute; KZN, KwaZulu-Natal.