HALF OF AMERICAN HIV IS DRUG-RESISTANT
By Daniel Haney
AP 18 Dec. 2001
Chicago -- A disturbing new study found that at least half of all
Americans under care for HIV infection carry viruses that are
resistant to some of the standard AIDS drugs.
HIV's relentless ability to mutate and grow impervious to AIDS drugs
is the single biggest challenge of treatment, and the new research
shows the magnitude of this problem.
Often patients with viruses that are resistant to some drugs can be
switched to other treatment regimens. But options are limited,
because viruses that elude one medicine can often outwit others that
are closely related.
Smaller studies have shown this resistance is widespread, but the
latest review is the first to examine the issue nationwide. It shows
that about half of the 209,000 people under physicians' care for HIV
in 1999 had viruses that were resistant to at least one of the 15
AIDS medicines on the market.
"This incredibly high prevalence is a bit scary. It has important
implications for treatment and for transmission of drug-resistant
virus," said Dr. Douglas Richman of the University of California at
Richman's findings were based on blood samples taken from 1,908 men
and women who were patients of doctors in a randomly selected sample
of U.S. physicians. He presented them Tuesday at an infectious-
diseases meeting in Chicago sponsored by the American Society for
"These are remarkable data," said Dr. Scott Hammer of Columbia
University. "This amount of drug resistance is striking. It shows
why we need new treatments."
The doctors found that two-thirds of the patients surveyed had
measurable levels of virus in their blood. This could occur because
they were taking inadequate amounts of medicine or because their
virus escaped complete suppression because it was drug-resistant.
It turned out that three-quarters of these people with measurable HIV
had virus that was resistant to at least one drug.
"I must admit, none of us thought it would be this high," Richman
said. "It's disappointing."
Dr. Ronald Valdiserri, deputy chief of sexually transmitted diseases
at the Centers for Disease Control and Prevention,
noted that these resistant viruses can spread to others, and this
limits treatment possibilities for newly infected people. "It
underscores the importance of prevention," he said.
Among the study's findings:
- People with the best access to care had the highest level of drug-
resistant virus. This is because they had often been exposed to many
- The highest level of drug resistance - 70 percent - was against drugs
known as reverse transcriptase inhibitors. This is the oldest class
of AIDS medicines and includes such drugs as AZT.
- Forty-two percent of viruses were resistant to protease inhibitors.
This medicine is a key ingredient of the AIDS drug combinations that
helped transform AIDS into a treatable disease in the mid-1990s.
- Resistance was highest in people whose helper cells - the primary
target of the AIDS virus - had fallen to the lowest levels.
- Drug resistance was less of a problem for people treated by very
experienced AIDS doctors with large numbers of patients.