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Drug-Resistant HIV Rises Among Newly Infected

Resistance in new infections rose fourfold between 1995 and 2000

WEDNESDAY, Aug. 7, 2002 (HealthDayNews) -- Drug resistance among people newly infected with HIV is growing.

The proportion of patients beginning treatment for a drug-resistant form of the AIDS virus nearly quadrupled -- from 3.4 percent to 12.4 percent -- between 1995 and 2000, a new study has found. Meanwhile, the incidence of multi-drug-resistant HIV rose even faster -- from about 1 percent to 6 percent -- during that span.

Infections resistant to antiviral drug combinations took longer to suppress and broke through again more quickly than those fully susceptible to the drugs, according to the study, which appears in tomorrow's issue of the New England Journal of Medicine.

Dr. Douglas Richman, an AIDS expert at the University of California, San Diego, and a co-author of the paper, said the results reflect in part the inherent ability of HIV to mutate in order to persist. Yet they also underscore an alarming trend among people with HIV to ignore safe-sex practices, he said.

"Someone who transmits a drug-resistant virus is likely to have taken drugs, so they obviously have seen a physician and they know they're infected," Richman said. "We suspect the vast majority [of the cases in the study] are from people in those situations."

The researchers analyzed susceptibility of HIV to drugs in 377 people in 10 cities in the United States and Canada. None of the people analyzed had received treatment. Most of them were homosexual men who'd acquired the disease through sexual contact with other men. Nine percent were women.

Genetic analysis also revealed a sharp jump in the proportion of mutations that have been known to increase the likelihood of resistance but aren't necessarily immune to antiviral drugs.

Richman said it's possible that heterosexually acquired HIV and infections passed by sharing tainted needles might have lower rates of resistance, though that hasn't been demonstrated.

Other research, including data collected since 2000, has also found increasing levels of drug-resistant HIV, so experts said the latest results aren't shocking.

One study reported earlier this year showed that half of the roughly 200,000 people in this country receiving treatment for HIV have at least one hardy strain.

Still, "this study is telling us that resistance is a problem," said Dr. Calvin Cohen, an AIDS expert at Harvard Medical School in Boston. "And whether the precise [level] is 5 percent or 25 percent, one of the main threats to the success of HIV treatment is resistance."

City-by-city looks at the problem, including the new report, turn up varying rates of drug-resistant HIV, Cohen said. Yet because people are so mobile, it doesn't matter if Miami's level is lower than San Francisco's if carriers of the virus take a trip to Minneapolis.

The increase in resistant HIV strains is probably due to two factors, Cohen said. Patients aren't always fully compliant with their medications, which gives the virus some breathing room. And doctors in the past didn't have the tools to treat it as aggressively as necessary, giving it a slap instead of a chokehold.

"The combination [of drugs] we used wasn't powerful enough," Cohen said. "If all we do is slow HIV down but not stop it, it will become resistant in weeks or even shorter."

Richman agreed that physician practices in this country have contributed to the rise of resistance in new infections.

In Europe, where HIV treatment is better standardized, rates of the problem are lower. They are also lower among the patients of American doctors with more experience treating HIV, he added.

What To Do

For more on drug-resistant HIV, check out Project Inform or the AIDS Treatment Data Network. To learn more about AIDS and HIV, visit the Centers for Disease Control and Prevention.

SOURCES: Douglas Richman, M.D., professor of medicine, University of California, San Diego, VA San Diego Health Care System; Calvin J. Cohen, M.D., M.Sc., clinical instructor, Harvard Medical School, Boston; Aug. 8, 2002, New England Journal of Medicine
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