DRUG-RESISTANT AIDS VIRUS SPREADING
By Daniel Haney
AP 8 February 2001
Chicago –– People who catch HIV are increasingly likely to encounter
mutant forms of the virus that are able to resist some of the drugs
commonly used to treat the infection.
Drug-resistant strains have been a major problem since the start of
treatment in the early years of the AIDS epidemic, but until recently
this resistance emerged as the virus evolved inside each patient's
body. Now, however, doctors say these resistant viruses apparently
are being passed on to others in significant numbers.
U.S. researchers Wednesday reported an abrupt upswing over the past
two years in the prevalence of resistant forms of the virus in newly
They said the cause of this increase is almost certainly the
widespread use of drug combinations that have revolutionized the
treatment of AIDS since 1996. These medicines have transformed HIV
from a death sentence to a manageable condition, but they have also
increased the number of outwardly healthy people whose bodies harbor
When all goes well, the drugs hold reproduction of the virus so low
that no resistant mutants can evolve. But often, the medicines fail
to work this well, and a virus gradually emerges that is resistant to
one or more of the drugs being taken.
"There are significantly greater numbers of patients who have failing
regimens and who transmit their virus," said Dr. Susan Little of the
University of California at San Diego.
Her study was conducted on 394 people in Dallas, Denver, Los Angeles,
San Diego, Montreal, Birmingham, Ala., and Vancouver, British
Columbia. She presented the results at the Eighth Annual Retrovirus
Conference in Chicago.
The patients were seen by doctors between 1995 and last May. All were
checked within three months of catching HIV.
Between 1995 and 1998, less than 4 percent of the patients caught
resistant virus. In 1999 and 2000, this rose to 14 percent. Six
percent of these had a virus that was resistant to two drugs.
Most of those who catch HIV never realize it until years later.
However, patients occasionally realize it soon after infection
because they get temporary flu-like symptoms. Some doctors recommend
immediate drug treatment for such patients.
In these cases, Little said doctors should check their patients'
viruses to see if they are resistant to any drugs before starting
Doctors believe that without treatment, patients' drug-resistant
virus eventually evolves back to the non-resistant form. However, a
record of the resistant virus is stored in patients' immune systems,
and it can re-emerge once treatment starts.
The growing spread of resistant virus "has tremendous important in
our ability to treat people effectively," said Dr. Douglas Richman,
another member of Little's team.
Another study, conducted by Dr. Hillard Weinstock of the Centers for
Disease Control and Prevention in Atlanta, raises the possibility
that the level of resistant virus varies greatly among different risk
Weinstock's team surveyed 603 people newly diagnosed with HIV in 10
cities. It found that 16 percent of white homosexual men had
resistant virus, compared with 3 percent of blacks who caught the
Two other studies from Switzerland and France also found high levels
of resistant virus, though resistance was more common there than in
the United States during the mid-1990s. In a study of 121 newly
infected patients, Dr. Marie-Laure Chaix of Necker Hospital in Paris
found that 9 percent had resistant virus in 1996, 7 percent in 1997,
6 percent in 1998 and 10 percent in 1999.