Background:  Because of the relatively short incubation period of sexually transmitted diseases (STD) and the relationship between STD and risk for HIV infection, patients seeking STD care may be at very high risk for acute HIV infection. Patients with acute HIV infection (HIV antibody negative but detectable HIV RNA) are at substantial risk of further spreading HIV because of high viral load, unknown infection status, and increased risk behavior. Recent advances in HIV testing allow for rapid point-of-care antibody testing and HIV RNA detection, ensuring timely identification and prevention counseling in patients with acute infection.

Methods:  Select patients at high risk of HIV infection were offered rapid HIV testing at the San Francisco municipal STD clinic (Oraquick Advance HIV-1/2 Antibody Test).  Persons who were rapid antibody test negative were tested for HIV RNA (Versant 3.0) using a 1-stage pooling protocol of 10 plasma specimens. Positive HIV RNA tests were confirmed by follow-up testing. We calculated the sensitivity and binomial exact 95% confidence intervals of the rapid HIV test.

Results:  Through June 2006, 716 persons had rapid HIV antibody tests, of whom 47 (6.6%) were HIV antibody positive. Among the 669 persons with rapid antibody negative tests, 9 (1.3%) were RNA positive and confirmed indicating an HIV rapid test sensitivity of 98.7% (95%CI 97.5 to 99.4%). All (100%) of patients received their positive RNA result, were counseled and referred into care. HIV RNA screening increased HIV case detection by 19% (9 of 47).
Conclusions:  The combination of rapid HIV antibody testing with more sensitive HIV RNA screening assured that HIV-infected patients learned their test results quickly, were not missed, and helped identify an additional 19% of those with HIV infection. Furthermore, patients with acute infection were identified and counseled when highly infectious, thereby potentially averting further transmission. Wider use of combined rapid antibody testing and RNA screening, particularly in STD clinic settings, could contribute to the reduction of HIV incidence.