Researchers expect greater HIV resistance to drugs by 2005

WASHINGTON -- The share of HIV infections that are drug-resistant will jump to 42 percent in San Francisco by 2005, according to researchers.

Estimating the current rate of drug resistance at 28.5 percent, the group used a mathematical formula to calculate its likely increase over the next few years.

HIV, human immunodeficiency virus, is the agent that causes AIDS.

The work of the team, led by Dr. Sally M. Blower of the University of California at Los Angeles, was published last week in the journal Nature Medicine.

The scientists calculated the increase in drug-resistant HIV since 1997 and used that to extend their forecast.

The primary reason for the increase, they said, is the development of drug resistance in the virus during treatment. The transmission of drug-resistant strains remains low, they said, estimating that it will account for just 16 percent of new HIV cases by 2005.

"The good news is that transmission of drug-resistant HIV will not become a major public health problem," Blower said in a statement. "The bad news is that the prevalence of drug-resistant HIV is already high and will continue to substantially increase."

A complex combination of drugs is used to treat AIDS, but this therapy demands a complicated dosage regimen difficult to maintain and that often causes severe side effects.