Background: Detection of acute HIV-1 infection (AHI) is critical for early HIV treatment and prevention. We identified AHI in men who have sex with men (MSM), and in transgender women (TGW), attending the Silom Community Clinic (SCC) for voluntary counseling and testing (VCT) services in Bangkok, Thailand and assessed associated risk factors.
Methods: The SCC offers voluntary HIV-1 counseling and rapid serologic testing for MSM and TGW. We used an HIV-1 rapid test (Determine) to screen for HIV. Positive results were confirmed by two additional rapid tests (DoubleCheck, SD Bioline). Persons with negative rapid tests were screened for AHI using a pooled HIV-1 nucleic acid amplification test (NAAT, Aptima). AHI in those with a NAAT-positive result was confirmed by viral load (Roche) or fourth-generation enzyme immunoassay (EIA, Abbott). AHI was defined as being anti-HIV-1 antibody negative with the presence of HIV-1 RNA or p24 antigen. We describe behavioral and laboratory factors for persons with AHI.
Results: From June 2009 to November 2015, 9,167 persons made 21,773 visits to VCT services. Overall, 8,747/9,167 (95%) assented to HIV testing; the prevalence of HIV-1 infection by rapid tests was 32.8% (95% CI 31.9-33.8). Among 5,874 persons with negative rapid tests, we performed NAAT testing in 5,806 (98.8%), and detected AHI in 68 (1.1%, 95% CI 0.9-1.4). Persons with AHI had a median age of 27 years (IQR 23-32), and 62% were aged 17-29 years. Characteristics of persons with AHI included recent unprotected anal sex (n=63, 93%), history of a sexually transmitted disease (n=28, 41%), hepatitis immunity (hepatitis B surface antibody, n=27, 40%, hepatitis A, n=16, 24%), and any AHI symptoms (n=19, 28%). However, 72% of persons with AHI did not report any AHI symptoms.
Conclusions: We detected AHI in 1.1% of MSM and TGW who initially tested HIV negative at SCC VCT. Incorporating screening for HIV-1 NAAT and p24 in persons reporting risk exposure or factors linked with AHI leads to detection of acute infection as resources allow, and increases the possibility of early treatment and prevention of HIV transmission.

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