July 21, 2006
Baltimore's switch from conventional HIV antibody testing to RNA-based testing could help authorities diagnose new cases more quickly, aiding prevention efforts. Dr. Joshua Sharfstein, the city's health commissioner, said the more sophisticated test "offers patients the opportunity to learn their HIV status earlier in the infection and gives the city the ability to understand where HIV infection is occurring now. That knowledge is the key to intervening and slowing down the spread of this virus."
Unlike HIV antibodies, which may not be evident for weeks after infection, the virus' RNA may be apparent within one week of infection. The RNA test is being used in east- and west-side health clinics, and the department plans to make it available for community HIV testing agencies.
North Carolina began using RNA testing in 2002. Dr. Peter Leone, medical director for the state's HIV prevention and care program, said after the testing found two newly infected college students, investigators were able to identify a network of bars and Web sites where students were meeting. "We have gone into these clubs with prevention messages and done a very effective campaign of harm reduction," Leone said.
More recently, RNA testing has been adopted, to varying degrees, by San Francisco, Los Angeles, Seattle and Rochester, N.Y. Colorado and Florida are also planning to incorporate RNA testing. More than a year ago, the Maryland Department of Health and Mental Hygiene began using the RNA test on blood samples submitted to its lab in Baltimore. That facility, however, receives specimens mainly from clinics in lower-prevalence areas outside the city.
Baltimore clinics and community agencies perform about 22,000 HIV tests annually, of which about 660 are positive, said Dr. Emily Erbelding, chief of medical services for the Health Department's STD section. RNA testing should help the city find 25 to 30 acutely infected people each year who would have been missed by conventional testing, she said.