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BackgroundIn Thailand, HIV transmission is well characterized in large urban centers such as Bangkok and Chiang Mai but less so outside of these areas. The main purpose of this study was to assess HIV incidence and associated risk factors in Nakhon Ratchasima and Ratchaburi.MethodsParticipants assigned male sex at birth were enrolled in this prospective observational cohort study between November 2017 and July 2018. HIV and syphilis testing and sociobehavioral questionnaires were administered over 18 months. HIV incidence rates and 95% confidence intervals (CIs) were estimated using a Poisson distribution. Cox proportional hazards models were used to estimate unadjusted and adjusted hazard ratios (aHRs) and 95% CIs for associations between potential risk factors and HIV seroconversion.ResultsA total of 1003 participants were enrolled. Overall HIV incidence was 1.56 per 100 person-years (95% CI:1.02-2.44) and similar at both sites. In the fully adjusted model, sex with a sex worker in the past six months was associated with reduced risk of seroconversion (aHR:0.10, 95% CI:0.01-0.77). In the reduced adjusted model, receptive anal sex (aHR:3.40, 95% CI:1.32-8.74) and STI diagnosis in the past six months (aHR:3.58, 95% CI:1.19-10.76) were associated with seroconversion, while sex with a sex worker in the past six months was associated with reduced risk of seroconversion (aHR:0.11, 95% CI:0.02-0.67). Additionally, 56% reported interest in taking PrEP and 82% reported willingness to participate in a hypothetical future vaccine trial.ConclusionsRecent receptive anal sex practices were associated with HIV acquisition in these populations, highlighting the continued need for interventions encouraging safer anal sex practices to reduce HIV incidence.

BackgroundChlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most common bacterial causes of sexually transmitted infection (STI) in the United States (US). The purpose of this study was to determine the frequency of reinfection during a six-month study period and to evaluate the retesting interval for those infected with CT or NG.MethodsWe conducted a prospective, six-month follow-up study among US military personnel with new onset, laboratory-confirmed CT or NG, recruited from an STI clinic at a large military base from January 2018 to January 2020. Each participant was randomly assigned to one of four groups, which differed only by the timing of the first study-associated follow-up visit after CT or NG diagnosis.ResultsOf the 347 initially recruited into the study, 267 participants completed a follow-up visit prior to their scheduled, final visit 6 months after initial infection. The median age at enrollment was 22 years and 41.0% were female. There were 32 (12.0%) reinfections (30 CT and 2 NG) after treatment of an index diagnosis of CT or NG within the six-month study period. Six of the CT reinfections were only detected at the final visit. A review of medical records revealed additional CT and NG reinfections. The probability of detecting a reinfection did not vary significantly by timing of follow-up.ConclusionsThe likelihood of detecting CT or NG reinfection did not differ according to time of follow up visit among study participants, thus supporting CDC guidance to retest three months post treatment. Efforts should continue to focus on STI prevention and risk reduction.