13 Feb Hormones, STIs, and vaginal bacteria
Does hormonal contraception create changes in cervicovaginal bacteria and does it affect risk of sexually transmitted infections for African sex workers?
Previous studies have reported an association between the use of injectable Depo-Provera for contraception and increased risk of HIV acquisition. Hormones may increase susceptibility to other sexually transmitted infections (STIs) or cause changes in the normal resident bacteria, called the cervicovaginal microbiota (VMB). These may be accompanied by genital immune activation and/or disruption of the vaginal mucosa.
We investigated whether hormonal status was associated with increased incidence and prevalence of STIs and VMB changes in a cohort of Rwandan female sex workers.
Oral contraceptive use was associated with increased human papilloma virus (HPV) prevalence and Chlamydia trachomatis incidence, and injectables with increased herpes simplex virus-2 (HSV-2) prevalence. Pregnancy was associated with a higher candidiasis incidence but lower HIV prevalence. Hormonal status was not associated with VMB composition, although oral contraceptive users had lower semi-quantitative abundance of Prevotella, Sneathia/Leptotrichia amnionii and Mycoplasma species in the vagina.
The increased HSV-2 prevalence among injectable users might explain the potentially higher HIV risk seen in these women in some studies. More research is needed to confirm these results and shed light on the underlying biological mechanisms.