MONDAY, July 8, 2002 (HealthDayNews) -- In another sign that AIDS is evolving into a different kind of threat, researchers have found a growing number of newly infected people are immune to the two most powerful kinds of HIV drugs.
The research suggests the problem of drug resistance is increasing, and that HIV-positive patients already under medical care are infecting others, says Dr. Samuel A. Bozzette, a professor of medicine who specializes in AIDS at the University of California at San Diego.
The drug-resistant strains are so widespread that they appear strong enough to infect a "substantial" number of people, Bozzette says.
The findings appear in this week's issue of the Journal of the American Medical Association, and were presented this weekend at the International AIDS Conference in Barcelona, Spain.
While still a significant killer, AIDS has transformed over the last seven years into a largely treatable disease in the United States. The AIDS "cocktail" -- a regimen of three types of drugs -- has boosted the immune systems of thousands of patients, making them strong enough to resist devastating secondary illnesses and eventual death.
However, HIV, the AIDS virus, is a slippery germ. Over just a few years, some strains became immune to AIDS drugs, mainly those known as nucleoside reverse transcriptase inhibitors (nRTIs). They are the oldest and weakest of the three classes of drugs, says study co-author Dr. Robert M. Grant, an investigator with the Gladstone Institute of Virology and Immunology at the University of California at San Francisco.
Grant and his colleagues studied 225 newly infected HIV patients from 1996 to 2001. None had been treated yet; newly infected patients aren't drug-resistant unless they were infected with strains that are.
About 27 percent of the patients had drug-resistant strains of HIV. The percentage that was immune to a class of drugs known as non-nucleoside reverse transcriptase inhibitors (nnRTIs) jumped from zero in 1996 to 13.2 percent in 2000, while those resistant to protease inhibitors grew from 2.5 percent to 7.7 percent over the same period.
Not all the findings are bad. The number of patients resistant to nRTIs -- including the well-known drug AZT -- actually dropped from 20 percent to 5.5 percent during the period studied.
Also, only one patient was immune to all three types of AIDS drugs. Grant says this is good news. Some researchers have warned of a coming AIDS "superbug" that will resist virtually any type of drug thrown at it.
"Our study doesn't show a rampant problem with fully drug-resistant HIV," Grant says. "The problem [of drug resistance] is bad, but it's not as bad as it could be."
Researchers are still trying to figure out why the most drug-resistant immune strains of HIV aren't out of control. One theory suggests the immune strains use up much of their energy by resisting drugs, and aren't strong enough to infect other people easily.
This means that drug resistance may not be as bad as it sounds because the strains will be weak, says Dr. Joshua Bamberger, medical director of Housing and Urban Health with the San Francisco Department of Public Health.
Bozzette says the study findings suggest the theory about weak drug-resistant strains may not be holding true.
Bamberger, however, says researchers need to know more and must follow AIDS patients infected with immune strains to see if their life spans are shorter than those of other patients.
Bamberger adds that HIV patients should avoid taking AIDS drugs until their immune systems deteriorate significantly in order to prevent resistance from developing early.
What To Do
This Gay Men's Health Crisis fact sheet has more about protease inhibitors.
Learn more about drug resistance and AIDS from AIDSmeds.com, which is supported by drug companies. Find out the basics of AIDS treatment at The Body.
