Infection with herpes simplex virus 2 (HSV-2) is propelling significant increases in the prevalence of HIV among non-injecting drug users in New York City. Publishing their findings in PLOS ONE, researchers studied 785 cocaine or heroin users who did not inject drugs between 1995 and 1999 and 1,764 such drug users between 2005 and 2011.

The participants filled out questionnaires and received HIV and herpes tests while attending drug treatment programs at Mount Sinai Beth Israel in New York City. HIV prevalence among them rose from 7 percent in the 1990s period to 13 percent in the 2000s period, with nearly even increases among various subgroups.

Coinfection with HIV and herpes type 2 was common in both periods, with an overall average of 97 percent of HIV-positive women and 67 percent of HIV-positive men coinfected with herpes. This compares with 80 percent of HIV-negative women and 43 percent of HIV-negative men infected with herpes .

The researchers found that the increase in HIV prevalence rates was mostly a function of an increase in HSV-2: Herpes infection rates only rose among HIV-coinfected participants between the two time periods. An estimated half of all HIV infections among men and 60 percent among women were attributed to herpes.

“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,” the study's lead author, Don Des Jarlais, PhD, a professor of psychiatry and of preventive medicine at Mount Sinai Beth Israel, said in a 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.”

To read the study, click here.

To read the press release, click here.