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Risk Factors for Incidence of Sexually Transmitted Infections Among Women in South Africa, Tanzania, and Zambia: Results From HPTN 055 Study

Kapiga, Saidi MD*; Kelly, Cliff MS; Weiss, Stephen PHD; Daley, Tara MS*; Peterson, Leigh PHD§; Leburg, Corey MHS; Ramjee, Gita PHD

Sexually Transmitted Diseases: April 2009 - Volume 36 - Issue 4 - p 199-206
doi: 10.1097/OLQ.0b013e318191ba01

Objective: To determine risk factors for sexually transmitted infections (STIs) among women in Durban and Hlabisa (South Africa), Moshi (Tanzania), and Lusaka (Zambia).

Study Design: Between 2003 and 2004, 958 women at risk of STIs were enrolled in a 1-year prospective study. They were interviewed at each monthly visit, and samples for STI testing were collected during quarterly and other visits when clinically indicated.

Results: The incidence of infections as measured in person-years at risk (PYAR) was as follows: overall trichomoniasis, 31.9/100 PYAR; chlamydial infection in South Africa, 19.5/100 PYAR; chlamydial infection in Tanzania and Zambia, 4.9/100 PYAR; gonorrhea in South Africa, 16.5/100 PYAR; gonorrhea in Tanzania and Zambia, 5.3/100 PYAR; overall syphilis, 7.5/100 PYAR; and overall HIV, 3.8/100 PYAR. The incidence of most STIs was highest among the South African sites, where chlamydial infection and gonorrhea were detected by using a more sensitive assay. Independent risk factors included age, hormonal contraceptive methods, and measures of sexual behavior, including number of sex partners and occurrence of anal sex in the past 3 months. Women with incident HIV infection were at increased risk of chlamydial infection [odds ratio (OR) = 5.5, 95% confidence interval (CI): 2.0–15.2]and gonorrhea (OR = 5.7, 95% CI: 1.9–17.0) in South African sites. Despite ongoing counseling during the study, high-risk sexual behaviors were common, and consistent condom use remained low.

Conclusions: The incidence of STIs, including HIV, was high among women in this study. These findings highlight the urgent need for effective HIV/STI prevention programs in this population.

A prospective study found high STI incidence among women in 3 sub-Saharan African countries. Independent predictors of STIs were age, hormonal contraceptive methods, genital symptoms, sexual behaviors, and HIV.

From the *Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK; the †Fred Hutchinson Cancer Research Center, Seattle, Washington; the ‡Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, Florida; the §Family Health International, Research Triangle Park, North Carolina; and the ∥HIV Prevention Research Unit, Medical Research Council, Durban, South Africa

The author thanks the HPTN 055 study team.

This study was sponsored by the Division of AIDS, US National Institute of Allergy and Infectious Diseases; US National Institute of Child Health and Human Development; US National Institute of Mental Health; US National Institute of Drug Abuse, and the US National Institutes of Health.

Supported by the HIV Network for Prevention Trials (HIVNET) and by the US National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, Department of Health and Human Services, through contract N01-AI-35173 with Family Health International. In addition, this work was supported by the HIV Prevention Trials Network (HPTN) and sponsored by the National Institute of Allergy and Infectious Diseases, National Institute of Child Health and Human Development, National Institute on Drug Abuse, National Institute of Mental Health, and Office of AIDS Research, of the National Institutes of Health, US Department of Health and Human Services and NIAID cooperative agreements U01 AI048006, U01 AI047972, and U01 AI048008 for participating HPTU organizations.

Correspondence: Dr. Saidi Kapiga, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. E-mail:

Received for publication December 30, 2007, and accepted October 17, 2008.

© Copyright 2009 American Sexually Transmitted Diseases Association