Scientists document increasing reports of second infection.

2003 AUG 6 - (NewsRx.com & NewsRx.net) -- Evidence is growing that "superinfection" with more than one strain of HIV may be more common than previously thought, experts said at an international AIDS conference.

Specialists say such cases, when patients are infected with one strain and then another years later, cause concern because it could make patients more ill and because it might make the design of a vaccine more difficult due to a proliferation of varieties of HIV.

Scientists reported at the conference three new cases of so-called superinfection in people who were initially doing well without drugs but became sick years later after a second HIV infection.

"Superinfection is sobering," said Dr. Anthony Fauci, the top AIDS official in the United States, who was not involved with any of the studies.

"If someone's virus is very well controlled so that their body is truly controlling the virus they have and then they become superinfected, that's worrisome," Fauci said. "That means that although you can mount an adequate response against one virus, the body still does not have the capability to protect you against new infection, which tells you that the development of a vaccine is going to be even more of a challenge."

Fauci said it is too early to tell how big a problem superinfection will become but that he does not believe superinfections are the reason patients suddenly deteriorate while on treatment.

At the meeting, Dr. Luc Perrin, a professor of clinical virology at the University of Geneva in Switzerland, reported finding superinfections in two Swiss intravenous drug users. In the study, Perrin followed 136 drug users with HIV and found that years after the initial infections, the amount of HIV in the blood of the patients suddenly shot up after years of control without drugs in five of the patients.