Speaker: Mayara Secco

The study investigated factors associated with the diagnosis of prevalent, incident, and recurrent bacterial Sexually transmitted infections (STIs). The focus was on men who have sex with men (MSM) and transgender individuals. These individuals were enrolled in Pre-exposure prophylaxis (PrEP) programs. Despite the high burden of STIs in Latin America, there is a notable lack of incidence data in the region compared to settings in the global North. The study seeks to address the gap and provide valuable insights into STI prevalence, incidence, and transmission dynamics. The study's primary objective was to explore factors associated with prevalent, incident, and recurrent bacterial STIs during the Implementing Pre-exposure Prophylaxis (IMPREP) study. Syphilis testing was conducted at baseline and during each quarterly visit. Participants also self-collected anal swabs for molecular detection of Chlamydia trachomatis and Neisseria gonorrhoeae at baseline and annually. Additional clinic visits were scheduled if participants reported STI-related symptoms during the study.

Prevalent STIs were defined as active syphilis, anorectal chlamydia, or anorectal gonorrhea identified at baseline. Incident STIs were defined as diagnosing the first bacterial STI after initiating PrEP. Recurrent STIs were either a second STI occurrence or a new infection if two different pathogens were identified simultaneously as the first infection. Since cure tests were not performed, laboratory criteria were used to assess resolution. Incident syphilis was recognized as a new positive treponemal test during quarterly visits if the baseline test was negative. For those already diagnosed with syphilis at baseline, non-treponemal test titers to identify incident cases were monitored. Similarly, incident Chlamydia and Gonorrhea were determined by positive results following a previous negative test. Logistic regression models were employed to identify factors associated with prevalent, incident, and recurrent bacterial STIs throughout the IMPREP study.

Out of 90,509 PrEP participants, 8,528 were tested for bacterial STIs at baseline. Most participants were cisgender men (94%), and 6% were transgender women. Approximately 60% were under 30 years old, and 70% identified as non-white. The baseline STI prevalence was 23%. Key factors associated with STI prevalence included being under 30 years old, identifying as Black, mixed-race, or Indigenous, and having lower educational levels. Additionally, not seeking PrEP independently and having multiple sexual partners were also linked to higher STI prevalence. These participants faced pre-existing vulnerabilities and could benefit from combined prevention strategies. For incident STIs, 7,558 participants were followed up. The incidence rate was 31.7 per 100 person/year, with anorectal chlamydia being the most common, followed by syphilis and anorectal gonorrhea. About 30% of participants were responsible for all STI diagnoses, and 60% of diagnoses were concentrated in 12% of participants. Factors associated with incident STIs included aged 18-24, identifying as Black, mixed-race, or Indigenous, previous PrEP use, more sexual partners, receptive anal sex, and use of poppers. Participants with pre-existing STIs at baseline were also at higher risk for new infections. Similar factors were associated with recurrent STIs, emphasizing the need to explore sexual network impacts on STI transmission.

In conclusion, the results enhance understanding of STI dynamics in Latin America, emphasizing the roles of age, sexual behavior, and substance use. They reveal high STI vulnerability at PrEP initiation and recurring infections in a small subset of users. These insights can guide public health strategies, including tailored prevention approaches like doxycycline and Gonorrhea vaccines. A person-centered approach and comprehensive sexual health assessments are essential for reducing HIV (Human Immunodeficiency Virus) and STI burdens. Additionally, addressing sex education and mental health is crucial for effective prevention in Latin America.

Expanding STI prevention studies, such as Doxy-PEP and Gonorrhea vaccines, is crucial, particularly for sexual and gender minorities. Involving community stakeholders in policy development and service organization is also essential. Therefore, addressing social determinants of health will improve prevention models for STI and HIV, targeting global inequities, disparities, and stigma.

The 25th International AIDS conference (AIDS 2024). 22nd-26th July, Munich, Germany