Researchers have come up with the first direct evidence that enough hepatitis C virus (HCV) sheds into the rectums of HIV-positive men who have sex with men (MSM) to transmit directly to another man’s penis during anal sex, even when no blood is present.

Publishing their findings in Clinical Infectious Diseases, researchers studied 43 MSM with HIV who had both recent and chronic HCV. They compared the hep C viral load in samples of the men’s rectal fluid and blood.

Twenty (47 percent) of the men had rectal hep C shedding; only one (2 percent) had visible bleeding. Having a blood viral load of greater than 100,000 international units per milliliter was associated with having detectable viral shedding in the rectum; 85 percent of those with a blood viral load that high had detectable rectal shedding.

The viral load of the rectal fluid ranged from 400 to 315,000.

The researchers concluded that based on the men’s median rectal fluid viral load, the surface of an average penis would be exposed to at least 2,300 international units of hep C for the duration of anal intercourse with an HCV-positive man. Transmission could also occur via sex toys.

“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,” the researchers concluded.

To read the study abstract, click here.