November 2001

HIV Highly Contagious Before Symptoms Show

NEW YORK (Reuters Health) - HIV may be highly transmissible before an infected person has the first, flu-like symptoms or before HIV tests can pick up the virus--underscoring the importance of consistent safe sex in preventing the spread of AIDS, researchers report.

The investigators studied five couples in whom HIV transmission occurred soon after one partner contracted the virus--and as early as one week before the partner developed the flu-like symptoms characteristic of early HIV infection.

``The main thing that's new is that we've shown for the first time that sexual transmission can happen readily and very soon after exposure,'' Dr. Christopher D. Pilcher of the University of North Carolina at Chapel Hill said in a statement.

Researchers have suspected as much, but no one had documented it, according to Pilcher. He and his colleagues report their findings in the October 10th issue of The Journal of the American Medical Association.

The period shortly after transmission is known as primary HIV infection, a time when virus levels in the blood soar and short-lived symptoms including fever, fatigue and swollen glands may set in. At this point, the immune system has not yet produced antibodies to the infection, so standard tests that detect HIV antibodies cannot pick up the infection.

In addition, researchers have theorized that during this window of time, high amounts of the virus are ``shed'' into the genital tract, making it a highly infectious time period. The current study suggests that is the case--highlighting, according to Pilcher, how vital it is to avoid unsafe sex practices.

``If you engage in unsafe sex,'' he said, ``you cannot assume that you are not infected or infectious just because you had a negative antibody test for HIV. The most commonly used tests can't show HIV for several weeks.''

Pilcher's team came to their conclusions by taking the couples' sexual histories and genetically analyzing the HIV in their blood samples. All transmissions had been suspected of occurring when one partner had a documented primary HIV infection.

The researchers conclude that each case of a documented primary infection presents a ``unique public health opportunity'' to track down that person's recent sexual contacts and prevent the further spread of HIV.