HCV transmission primarily occurs through exposure to blood, and persons who inject drugs at greatest risk.
But when Mount Sinai researchers observed a large increase in the number of new cases of HCV transmission among HIV-infected men who did not inject drugs, they took a closer look to examine the role of sexual transmission among these men.
The researchers identified 74 HIV-infected men between October 2005 and December 2010 who had documented new HCV infection and yet reported no other risk factor for HCV infection, including injection drug use.
And they found that the men who had recently contracted HCV were 23 times more likely to have had unprotected anal sex with men.
In addition, HCV genetic analysis suggested that HCV was transmitted within social networks of these men, consistent with the presence of a city-wide epidemic.
"While hepatitis C is rarely transmitted among stable heterosexual couples, this is clearly not the case among HIV-infected MSM in New York City," said Dr. Daniel Fierer, Assistant Professor of Medicine and Infectious Diseases at Mount Sinai School of Medicine.
"MSM, and to some extent their health care providers are generally not aware that having unprotected receptive sex can result in HCV infection.
"The good news is that the cure rate for new HCV infections is very high with early treatment, but without regular testing of the men at risk, these largely asymptomatic infections may be missed and this opportunity lost," he added.
The results of the study are published in the latest edition of the CDC`s Morbidity and Mortality Weekly Report.