Drug-resistant HIV strains are on the rise and improving their ability to transfer from person to person, a new study by researchers at the University of California-San Francisco (UCSF) and University of California-Los Angeles (UCLA) shows.
Modeling by Dr. James Kahn, of the UCSF Positive Health Program at San Francisco General Hospital, and Dr. Sally Blower, director of UCLA's Center for Biomedical Modeling, indicates 60 percent of drug-resistant HIV strains circulating in San Francisco are infectious enough to cause self-sustaining mini-epidemics.
"Drug-resistant strains are generally less infectious, but we've found they're not much less infectious," said Blower. "For some of these strains, they've reached a threshold at which they're generating their own epidemic."
According to the researchers, one reason resistance is increasing stems from the protocols applied in developed countries, which call for early treatment to help keep patients healthy. But the longer a patient is on a drug, the greater the chance he or she will become resistant to it.
"Unless things change significantly, what we see is that one of the major classes we use to treat patients will have a rise in resistance," said Kahn.
Dr. Grant Colfax, director of HIV prevention and research at the San Francisco Department of Public Health, cautioned that while the study is important, it should not prompt doctors to change how they treat HIV patients. "What I'm concerned about is that people will use this paper to not treat or to delay treatment," he said. "Resistance should figure into clinical decisions. But you have to consider the huge benefits of early treatment for the individual and for society."
The authors and other experts said the results emphasize the urgency of developing new drug therapies as older ones are sidelined by drug-resistant virus, and the necessity of funding early drug-resistance testing for patients.
The study, "Evolutionary Dynamics of Complex Networks of HIV Drug-Resistant Strains: The Case of San Francisco," was published in Science (2010; doi:10.1126/science.1180556).
01/15/10
UNITED STATES: Study Warns of HIV Changes
Source: San Francisco Chronicle:: Erin Allday; Courtesy of the CDC National Center for HIV, STD, and TB Prevention