A new study in the journal Science shows drug-resistant HIV strains to be a growing problem, arguing that 60 percent of the strains resistant to antiretroviral treatment currently circulating in San Francisco are capable of spawning their own epidemics.

In the United States, the HIV pandemic is fought with drugs, education, testing, and research that are often limited in poorer nations.

But while wealthy countries like the U.S. can deploy a wide arsenal of drugs to battle the spread of HIV, new drug-resistant strains of the disease may be frustrating efforts to win the long-term fight against HIV/AIDS both within the U.S. and around the globe (see related AIDS Beacon article about drug resistance).

Adding to the growing body of evidence about the detrimental effect of drug resistance is an article recently published in the medical journal Science, which outlined a mathematical model that researchers used to track different strains of HIV in San Francisco to predict future patterns of the disease.

Researchers noted that ease of transmission is one of the most troubling aspects to the disease pattern in San Francisco; each infected individual is capable of causing more than one new resistant infection.

Based on their data, researchers also predicted that in the next five years additional drug-resistant strains will emerge in San Francisco, marking a potentially serious setback to public health should the strains spread globally.

With the rise of these drug-resistant strains, HIV treatment can become trickier for patients, as physicians may be forced to resort to different antiretrovirals to bring the disease under control.

Although drug-resistant strains of HIV can arise anywhere, its effects could differ dramatically depending upon the country in which it appears.

Whereas patients in San Francisco and across the U.S. have access to a broad range of antiretrovirals should one regimen fail, patients in poorer countries have much more limited treatment options. Recent news of drug-resistant HIV strains in South Africa are, therefore, a troubling development.

According to the World Health Organization, HIV treatment options are generally simple for those in resource-strapped nations, with one front-line therapy and one potential alternative available. If these treatments are ineffective, the disease may continue unabated.

For more information, please see the abstract in Science.