July 10, 2014
HIV infection among heterosexual non-injecting drug users in New York City has doubled in the past two decades. A study in PLOS ONE, by researchers affiliated with New York University's Center for Drug Use and HIV Research (CDUHR), makes a strong case for a major causal factor: herpes simplex virus type 2 (HSV-2).
The researchers followed participants in Beth Israel Medical Center's drug detoxification and methadone maintenance programs in New York City in 1995-1999 and 2005-2011 -- all of whom reported current heroin and/or cocaine use and no injection drug use.
A structured questionnaire was administered and serum samples collected for HIV and HSV-2 testing.
HSV-2 coinfection was common in both time periods.
An average of 97% of HIV-positive female participants were coinfected with HSV-2 while an average of 67% of HIV-positive male participants were coinfected.
The increase in HIV prevalence was predominantly an increase in HSV-2/HIV coinfection, with relatively little HIV mono-infection in either time period.
The estimated population-attributable risk percentages indicated that approximately half of the cases of HIV acquisition among female participants was caused by HSV-2 infection while approximately 60% of HIV transmission from females was caused by HSV-2 infection.
A similar, though less extreme, pattern was evident among males.
In other words, people infected with HSV-2 are at increased risk of becoming infected with HIV, and people infected with both HSV-2 and HIV are at increased risk of transmitting HIV to others. HSV-2 is known to increase both susceptibility to and transmissibility of HIV.
"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," noted Don Des Jarlais, Ph.D., the deputy director of the CDUHR's Infectious Diseases and Interdisciplinary Research Methods Core.
Jarlais is also the director of research at Beth Israel Medical Center's Baron Edmond de Rothschild, Chemical Dependency Institute; a senior research fellow with National Development and Research Institutes; and the study's lead author.
"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," Jarlais said.
Katherine Moriarty is a consultant and freelance writer, based in Vancouver. She has 10 years of experience in the intersecting fields of public health and community development, with a focus on bloodborne virus policy and programming.
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