The emergence of drug-resistant strains of HIV could one day threaten efforts to control the global HIV pandemic, according to a study published online Thursday in the journal Science, HealthDay News/U.S. News & World Report reports. The researchers based their findings on “a mathematical model that tracks the transmission of multiple strains of HIV” in San Francisco, the news service writes (1/14).

The report asserts that “drug-resistant strains [in the city] are improving their ability to transfer from person to person,” the San Francisco Chronicle reports. “According to their research, about 60 percent of the drug-resistant strains circulating in San Francisco are infectious enough that they could create mini-epidemics among HIV-positive patients,” the newspaper writes adding that “San Francisco public health officials emphasized that drug-resistant HIV is not a health crisis and said that while the study is interesting, they don’t expect it to change how doctors treat people with HIV infections” (Allday, 1/15).

According to the researchers, the mutant strains run the risk of reversing progress made in HIV treatment programs in developing nations, where there is little access to alternative medications when resistance to first-line therapies occurs, Bloomberg/Business Week reports. “If the resistant strains we have identified in our analyses evolve in these countries, they could significantly compromise HIV treatment programs,” the researchers wrote (Bennett, 1/14).

“This isn’t just about San Francisco. It’s basically about many other communities in resource-rich countries and has significant implications for global health,” study senior author Sally Blower, director of the Center for Biomedical Modeling and a member of the AIDS Institute at the University of California, Los Angeles, said in a university news release, according to HealthDay News/U.S. News & World Report. “San Francisco is like the canary in the mine. In fact, the most significant implications of our work are for countries where treatment is just being rolled out” (1/14).

Researchers say the results of their study cast doubt on a 2008 study by WHO that predicted “testing everyone for HIV in hard-hit African countries and treating all infections immediately may eliminate most of the virus’s spread,” because it did not account for the possibility of drug-resistant HIV strains, Bloomberg/Business Week writes (1/14).

TIME writes though “[c]urrent treatment guidelines do not call for the prescription of antiretroviral drugs until there is evidence of progressive damage to the immune system,” some health experts have advocated “a ‘test and treat policy‘ for populations with high HIV rates, as in major Western cities and parts of the developing world. …In November, WHO held a conference in Geneva to discuss whether the policy should be rolled out through its various agency programs.”

The magazine continues, “According to the team behind the Science study, however, that could prove disastrous. ‘Test and treat has been designed based on overly simplistic modeling. It is misguided and could lead to very serious public-health problems in resource-constrained countries,’ Blower says.” The article includes comments by Alvaro Bermejo, executive director of the International HIV/AIDS Alliance, who says the Science study illuminates the need for an HIV vaccine and patent pools for HIV drugs (Harrell, 1/14).