Rapid-detection test for HIV infection not widely used

At present, there are two standard tests that can detect the presence of the HIV virus: One detects HIV antibodies in the patient's saliva or blood, while the other tests for the virus's RNA. The antibody test is unlikely to detect infections that have taken place within the past month, but the RNA test can find infections that have taken place within a week to 10 days.

However, to date the RNA test has not been used very often. And that's a problem, given that as much as 50 percent of all new HIV transmissions are from the newly infected, studies suggest. Finding patients with new infections sooner and counseling them can prevent them from spreading their infection to others, experts say.

Why is such a valuable test used less often than one that doesn't detect the virus as quickly? Among reasons, it's because RNA testing is expensive and involves complicated lab work--not to mention that it doesn't provide immediate results.

Fortunately, a less expensive option that offers some of the benefits of RNA testing may be on the way. The CDC recently began a study comparing RNA testing with an advanced version of the test, the antibody-antigen test, which can detect a substance produced by the virus in the early stages of infection.

The antibody-antigen test, which appears to be able to identify 85 percent of acute HIV infections picked up by the RNA test, could be commercially available in 2010.

To learn more about these tests:
- read this article from The New York Times