We examined recency of infection in serum samples obtained from 69 newly identified HIV-positive cases in a sample of 1000 men who have sex with men (MSM) in Bogotá. HIV antibody avidity assays were performed using the Architect HIV Ag/AB combo. Avidity indices ranged from 0.62 to 1.22, with a cut-off score below 0.80 indicative of recent infection. Two samples were classified as recent, six fell within the gray zone (0.75 to 0.85), and the remaining 61 were considered established infections. Results provided evidence of widespread, long-term, undiagnosed HIV infection, as well as an estimate of one-year incidence at .25 in the population of MSM in Bogotá. This incidence rate is approximately 8.5 times the rate estimated for the general adult population in Colombia. The large proportion of newly diagnosed cases found among individuals with established infections indicates that many MSM in Bogotá are living with HIV for extended periods without being diagnosed and treated. Greater efforts to detect and treat undiagnosed infections are crucial to decrease HIV incidence and increase maximum effectiveness of medical intervention. Given the over-representation of MSM and transgender women in the HIV epidemic in Colombia, such efforts should specifically target this population.
Keywords: Colombia; HIV; avidity index; men who have sex with men; recent infection; undiagnosed infection.