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Wave of Mutant HIV May Undo Years of Drug Progress, Study Says
  By Simeon Bennett
Jan. 15 (Bloomberg) -- Strains of mutant HIV emerging in the U.S. and Europe threaten to undermine progress made in expanding access to treatment in poor countries, a study published online by the journal Science found. About 60 percent of drug-resistant HIV strains circulating in San Francisco can spur self-sustaining epidemics as patients who haven't been treated spread them, researchers from the University of California, Los Angeles said in the study. Similar trends are emerging in other rich cities including New York, Chicago and London, said Sally Blower, a professor of mathematical biology, who led the research.
Mutant strains are already starting to spread in poorer nations such as South Africa, where there is little access to back-up medicines when resistance develops, Blower said. Newer treatments will likely curb the spread of drug-resistant HIV in San Francisco and other wealthy cities, where patients have better access to alternative treatments, she said.
"If the resistant strains we have identified in our analyses evolve in these countries, they could significantly compromise HIV treatment programs," Blower and colleagues wrote. Mutant forms "pose a great and immediate threat to global public health," they said.
The study casts doubt on research by World Health Organization experts published last year that predicted testing everyone for HIV in hard-hit African countries and treating all infections immediately may eliminate most of the virus's spread. That model, known as "test and treat," is flawed because it doesn't take drug resistance into account, Blower said in a telephone interview.
'Recipe for Disaster'
"Universal test and treat is just a recipe for disaster," she said. "Our modeling is saying the drug resistant strains that you will generate from this kind of strategy are ones that will be very strong, transmissible, and therefore you will get an awful lot of problems."
The continued use of drugs to which HIV has become resistant favors the survival and spread of mutant strains because the medicines eliminate the regular form, allowing carriers to transmit resistant strains, Blower said.
About 33.4 million people were infected with the AIDS- causing virus worldwide as of the end of 2008, according to the WHO, making it the world's most prevalent infectious disease. More than 4 million people in low- and middle-income nations were receiving treatment as of the end of 2008, a 10-fold increase over five years, the WHO said last year.
About 13 percent of people newly infected with HIV in San Francisco get drug-resistant strains, Blower and colleagues said in the study yesterday. The extent of HIV drug resistance in developing nations hasn't been measured because of a lack of reliable data, the WHO said on its Web site.
Computer Model
Blower and colleagues developed a computer model to trace and predict resistance to three classes of HIV drugs known as PIs, NRTIs, and NNRTIs in San Francisco. The greatest resistance was to NNRTIs, a category that includes Bristol-Myers Squibb Co.'s Sustiva and Boehringer-Ingelheim GmbH's Viramune, said James Kahn, an associate director of the HIV/AIDS Clinic at San Francisco General Hospital, who participated in the research.
Patients who fail those drugs in San Francisco often switch to Intelence, made by Johnson & Johnson's Tibotec unit, or Merck & Co.'s Isentress, Kahn said in a telephone interview.
The model predicted that resistance to NRTIs, such as Gilead Sciences Inc.'s Truvada, and PIs including Abbott Laboratories' Kaletra, will remain at current levels until 2013, while resistance to NNRTIs will increase.
"In Africa NNRTIs are the backbone of the treatment regimen," Kahn said. "Unlike San Francisco, where we have a lot of options to switch people to, they don't have that many options in Africa."
The study was funded by the U.S. National Institute of Allergy and Infectious Diseases.
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