July 2, 2014
On June 27, National HIV Testing Day, the U.S. Centers for Disease Control and Prevention (CDC) released updated recommendations for HIV testing that revolve around better diagnosing acute HIV.
Currently, a standard HIV antibody test detects the presence of antibodies that typically take two to eight weeks to develop. The updated guidelines recommend using a fourth-generation HIV test, which is a combination antibody-antigen test. These tests detect both HIV antibodies and the p24 antigen, a protein that is part of HIV itself. Because p24 can be detected four to seven days sooner than antibodies, using combination tests as the standard can help identify HIV cases earlier.
According to the guidelines, patients who test positive using the combination method should then be tested with an antibody differentiation immunoassay to distinguish between HIV-1 and HIV-2. If that test is negative or indeterminate, patients should then be tested with a nucleic acid test (NAT) to either confirm HIV diagnosis or determine a false positive.
"Today, CDC is recommending a new approach for HIV testing in laboratories that capitalizes on the latest technology to improve diagnosis of acute infection, the earliest stage of HIV infection when people are most likely to transmit the virus," said Jonathan Mermin, M.D., M.P.H., director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, in a statement.
"Identifying acute infections has long been one of our nation's biggest HIV prevention challenges, since these infections eluded traditional testing technologies. But with consistent and widespread use of this new testing method, we can diagnose people several weeks earlier than before. CDC is supporting laboratories to adopt this new approach as quickly as possible," Mermin concluded.
Warren Tong is the research editor for TheBody.com and TheBodyPRO.com.
Follow Warren on Twitter: @WarrenAtTheBody.