A recent study involving young Kenyan men who have sex with men and transgender women reveals that individuals using pre-exposure prophylaxis (PrEP) for HIV prevention are significantly more likely to contract bacterial sexually transmitted infections (STIs) such as gonorrhoea and chlamydia.

Conducted across Kisumu, Nairobi, Malindi, and Mtwapa, the research tracked 650 HIV-negative participants aged 18 to 29, testing them at multiple sites including the throat, genitals, and rectum. Findings showed that those on PrEP had a 75% higher chance of acquiring these STIs compared to non-users.

Key Findings

  • Approximately 27 new chlamydia or gonorrhoea infections occurred per 100 participants annually.
  • Participants with prior infections were over three times more likely to be reinfected despite treatment.
  • Many infections were asymptomatic, facilitating unnoticed transmission.

The researchers emphasized that PrEP remains highly effective in preventing HIV, reducing sexual transmission risk by over 99% when taken correctly. However, it does not protect against bacterial infections, which continue to pose a public health challenge.

According to the study authors, the increased STI rates among PrEP users reflect ongoing exposure risks inherent in their sexual networks rather than any causative effect of the medication itself. They urged healthcare providers to integrate regular STI screening, treatment, and education into HIV prevention programs, especially for high-risk groups.

"STI prevention and treatment should include partner notification and clear messaging that PrEP does not prevent other STIs," the researchers stated.

Implications for Public Health

The study highlights the critical need for comprehensive sexual health strategies that combine HIV prevention with robust STI services. It also calls for innovative approaches to reduce bacterial infections while expanding access to PrEP.

Limitations noted by the team include the study's focus on specific high-risk populations, limited throat sample testing due to funding, and incomplete data on medication adherence and partner treatment.

Published in BMJ Open, the research involved collaboration between the Kenya Medical Research Institute-Wellcome Trust, University of Nairobi, Nyanza Reproductive Health Society, University of Oxford, and other partners.