The herpes-2 virus has led to higher HIV infection rates among heterosexual New Yorkers who use non-injectable drugs.

The HIV-2 infection rate among such drug users has doubled during the past generation from seven percent to 14 percent to surpass that of people who inject drugs, a new study in PLOS ONE reported on Sunday. At the same time, HIV infection rates have fallen among injectable-drug users by 10 percent since the mid-1990s, according to Don Des Jarlais, a psychiatry and preventive medicine professor at Mount Sinai Beth Israel who led the study.

"Heterosexual intercourse is usually not very efficient for transmitting HIV, but the efficiency of heterosexual transmission nearly triples in the presence of herpes simplex virus type 2," Des Jarlais said in a press release. "In New York City, we have done an excellent job of reducing HIV among persons who inject drugs and we must now put more efforts into reducing sexual transmission associated with non-injecting drug use."

But the study doesn’t necessary mean that HIV infection rates are rising in general, according to Des Jarlais, who also serves as deputy director of New York University’s Research Methods and Infectious Diseases Cores at the Center for Drug Use and HIV Research. Rather, co-infections involving herpes (HSV) and 2/HIV are becoming increasingly more common. And while it’s good that community organizers and public health officials discourage the sharing of dirty needles among injection-drug users, additional interventions should be targeted at other populations within the city, and elsewhere, to prevent the spread of HIV.

Presently, New York City’s Department of Health and Mental Hygiene has initiated an effort to treat people infected with HIV as part of a broader effort to prevent transmission to others. Those residents are given anti-viral medications for free as a public health measure. However, the Obama administration has just upped the ante for best practices, recommending that people who are not infected but deemed highly at risk begin receiving antiviral medications, too.

"If we can implement these programs on a large scale, we should be able to control sexual transmission of HIV in the city, and achieve the goal of an "End to the AIDS Epidemic," Des Jarlais said.

Source: Des Jarlais Don C, Arasteh K, McKnight C, et al. HSV-2 Co-Infection as a Driver of HIV Transmission among Heterosexual Non-Injecting Drug Users in New York City. PLOS ONE. 2014.