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Background:  Since the first AIDS patient was reported in 1985 until March 2004, 2679 individuals with HIV have been reported in South Korea. HIV reporting rates have increased about 35% over each previous year. We describe serological and virological test results of individuals with early HIV infection and assessed the utility of HIV antigen or HIV RNA viral load.

Methods:  By a national HIV testing strategy in South Korea in 1999 to 2004, we confirmed 1804 newly diagnosed HIV⁺ individuals. Sera or plasma were tested by enzyme immunoassay (EIA), particle agglutination, and Western blot for HIV antibody. Patients described as acutely infected were tested for HIV EIA antigen or viral RNA load.

Results:  Individuals with early HIV infection have increased continuously from 0.54% in 1999 to 5.60% in 2003. The median follow-up interval from indeterminate to seropositive was 10.5 days. Among 63 individuals with early HIV infection, 3, 6, 3, and 12 cases were found to be non-reactive to enzyme immunoassay, particle agglutination, Western blot antibody tests, and enzyme immunoassay antigen test at the first sera, respectively. But 7 cases with non-reactive HIV antibody tests showed positive by the enzyme immunoassay antigen test. Also, the median plasma viral RNA level of early HIV-infected individuals was 5.130.97 log copies/mL.

Conclusions:  The proportion of early HIV infection among newly diagnosed individuals with HIV in South Korea has increased yearly. A highly sensitive HIV RNA viral load test and HIV antigen test provided valuable information for the interpretation of HIV status.

Keywords: HIV early infection; antigen test; HIV RNA viral load