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INCIDENCE OF HSV-2 AND HIV IN A COHORT OF KENYAN ADOLESCENT GIRLS
Alison C. Roxby1, Amalia Magaret1, Stacy Selke1, Murugi Micheni2, Lynda M. Oluoch2, Tiffany Yuh1, Bhavna Chohan2, Catherine Kiptinness2, Kenneth Ngure2, Nelly R. Mugo2, Anna Wald1
1University of Washington, Seattle, WA, USA,2Kenya Medical Research Institute, Nairobi, Kenya
Herpes simplex virus-2 (HSV-2) infection is a powerful cofactor for HIV acquisition in sub-Saharan Africa. Young women acquire HSV-2 and HIV earlier than men, but individual factors influencing HSV-2 incidence are not known. HSV-2 acquisition may be a modifiable risk factor for reducing HIV incidence.
Adolescent girls aged 16-21 were recruited at a suburban clinic in Thika, Kenya. Eligible participants were both HIV and HSV-2 seronegative and reported either sexual naiveté or having had one lifetime sexual partner. Girls under age 18 needed parental consent to participate. Quarterly testing was done for incident HIV-1 by ELISA and HSV-2 by the Focus ELISA test. HSV-2 PCR testing of genital swabs was also done quarterly to detect infection as early as possible. Incident HSV-2 infections were confirmed by Western blot. Girls were provided comprehensive reproductive health care including STI screening, contraception, condoms, and more recently, access to PrEP. We assessed potential associations of baseline characteristics with HSV-2 seroconversion using Fisher's exact test for dichotomous measures and Wilcoxon rank-sum test for continuous measures.
We enrolled 400 participants with a median age of 18.6 years (IQR 16-21). The majority (322 girls, 80.5%) reported no history of sexual intercourse, while 78 (19.5%) reported sex with 1 lifetime partner. Over 4 years, with a median follow-up of 33 months per person, we detected 19 cases of HSV-2 and 2 cases of HIV. Incidence of HSV-2 was 21 cases per 1000 person/years (py); 45 per 1000 py among those with any STI at baseline and 16 per 1000 py among those without. For HIV, incidence was 2 cases per 1000 py. HSV-2 seroconversion was significantly associated with higher Nugent score at baseline (p=0.028), and there was a trend toward association for girls with baseline detection of STIs (p=0.058) and baseline diagnosis of bacterial vaginosis (p=0.072). Similar to other adolescent cohorts, some participants with STIs denied having sexual intercourse.
We present the first estimates of HSV-2 incidence in a cohort of sexually naïve young women followed over four years in Kenya. Higher Nugent scores and presence of other STIs were significantly correlated with incident HSV-2. Interventions to prevent STIs and promote healthy vaginal microbiota could influence HSV-2 acquisition in this age group.