November 29, 2016
2 min read

HCV shed in rectums of HIV-infected MSM

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Enough hepatitis C virus is shed into the rectal fluid of HIV–infected men who have sex with men to directly infect sexual partners, according to a study recently published in Clinical Infectious Diseases.

“The epidemic of sexually-transmitted HCV infection among HIV–infected MSM was first identified over a decade ago,” Daniel S. Fierer, MD, associate professor of infectious diseases at the Icahn School of Medicine at Mount Sinai, New York, and colleagues wrote. “Despite seven case-control studies that confirmed sexual transmission since these initial reports, there are only a few consistent, albeit not uniformly accepted, findings.”

The researchers added that there has been “significant controversy” over which bodily fluids are responsible for HCV transmission in HIV-infected MSM. 

To study the mechanisms of HCV transmission during sex, Fierer and colleagues obtained rectal fluid samples from HIV–positive MSM with HCV coinfection (n = 45) between May 2012 and November 2014. The researchers compared patients’ blood HCV viral load with their rectal HCV viral load.

The median age of the patients was 43 years, and 60% were white. Forty-three were prescribed combination ART, 51% of whom had not achieved virologic suppression. Ten patients (22%) had a history of AIDS, but none had a CD4 count less than 200 cells/µL.

Researchers detected HCV in the rectal fluid of 20 (47%) patients. HCV shedding was associated with a blood viral load greater than 5 log10 IU/mL (P = .01). Eighty-five percent of patients with a blood viral load greater than 5 log10 IU/mL showed rectal shedding. Rectal fluid viral load ranged between 2.6 and 5.5 log10 IU/mL. According to Fierer and colleagues, the average human penis would be exposed to a minimum of 2,300 IU of HCV during anal sex based on a median rectal viral load of 2.9 log10 IU/mL.

“Taken together with the majority of epidemiological evidence as well as our recent work demonstrating that HCV is shed into semen, also at levels sufficient to transmit HCV during sex among MSM, we believe that semen and rectal fluid, rather than frank blood from the rectum, are likely the fluids that mediate most HCV infections in this epidemic,” the researchers wrote. “With this preponderance of evidence, we suggest it is now time to readjust the paradigm of HCV transmission requiring significant rectal trauma or bleeding, which misleads both susceptible MSM as well as the research community. Finally, we must develop an appropriate public health campaign to educate MSM about these routes of HCV infection to reverse the HCV epidemic among HIV-infected MSM. – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.