Detection of acute HIV infections in high-risk patients in California.

Background: Given the strong relation between sexually transmitted diseases (STDs) and the spread of HIV infection, recent outbreaks of syphilis in the United States could lead to increased rates of new HIV infection. STD clinics serving persons at risk for syphilis would be logical sites to monitor rates of acute HIV infection. The detection of acute HIV infection, however, is not routine and requires the use of HIV RNA testing in combination with HIV antibody testing.

Methods: To determine the rate of acute HIV infection, we performed HIV RNA testing on pooled HIV antibody-negative specimens from persons seeking care at San Francisco City Clinic (SFCC) and from men seeking care at 3 STD clinics in Los Angeles. We compared prevalence of acute HIV infection among those groups.

Results: From October 2003 to July 2004, we tested 3075 specimens from persons at the SFCC, of which 105 (3%) were HIV antibody-positive and 11 were HIV RNA-positive/HIV antibody-negative, resulting in a prevalence of acute HIV infection of 36 per 10,000 (95% confidence interval [CI]: 26 to 50 per 10,000) and increasing by 10.5% the diagnostic yield of HIV RNA testing compared with standard testing. From February 2004 to April 2004, 1712 specimens were tested from men at 3 Los Angeles STD clinics, of which 14 (0.82%) were HIV-positive by enzyme immunoassay testing and 1 was HIV RNA-positive/HIV antibody-negative, resulting in a prevalence of 6 per 10,000 (95% CI: 3 to 13 per 10,000) and increasing the diagnostic yield for HIV infection by 7.1%.

Conclusions: In our study, the addition of HIV RNA screening to routine HIV antibody testing in STD clinics identified a substantial increased proportion of HIV-infected persons at high risk for further HIV transmission, who would have been missed by routine HIV counseling and testing protocols. Further evaluation of the addition of HIV RNA screening to routine HIV antibody testing is warranted.