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Until now it has been assumed that HCV transmission during anal intercourse occurred as a result of bleeding, or perhaps through transmission in semen. HCV is easily transmitted in blood; just 10 to 20 hepatitis C virions are enough to establish infection through contaminated medical equipment or used injecting equipment, it has been estimated.

Sexual transmission of HCV has been theorized to take place as a result of contact between blood and the mucosa of the penis, or contact with damaged tissue on the hand during fisting. Transmission has also been theorized to occur as a result of the transfer of blood containing HCV from one person to another on the penis, on a gloved fist, or on sex toys during group sex.

Another presentation at the Liver Meeting by the same group, led by Daniel Fierer, reported that HCV was present in 27% of 3 paired samples of blood and semen collected from 33 HIV and HCV coinfected men, with virus levels sufficient to transmit hepatitis C.

The possibility that HCV might be present in the fluid on the surface of the rectal mucosa had not been previously explored. Seeking to understand how HCV is being transmitted widely among men who have sex with men, especially those with HIV infection, researchers recruited 45 men who have sex with men coinfected with HIV and HCV, 12 of whom were acutely infected.

Study participants had a median age of 43 years, 60% were white, and 87% had genotype 1a HCV infection. Participants had high CD4 cell counts (median 582 cells/mm³) but HIV viral load suppression was not reported. Participants had moderately high HCV viral load (5.89 log IU/mL), and those with acute HCV infection had somewhat higher median viral load (6.42 log IU/mL) than those with chronic HCV infection (5.62 log IU/mL).

Men underwent rectal fluid collection by insertion of a swab which sampled the fluid on the rectal mucosa approximately 7 cm beyond the anus. Fluid was analyzed for HCV RNA using the COBAS HCV test, which has a lower limit of detection of 7 IU/mL. Swabs were analyzed for blood. Participants also underwent HCV RNA testing of blood, as well as tests for rectal sexually transmitted infections and syphilis.

Hepatitis C virus was detected in 20 of the 45 specimens (47%) (2 samples could not be processed). The median HCV RNA was 2.92 log IU/mL, and the level of HCV RNA in rectal fluid was strongly correlated with the level in blood. Rectal HCV was much more likely to be detected in participants who had a high HCV viral load in blood. Rectal HCV detection was significantly associated with having an HCV viral load in blood above 5 log IU/mL.

There was no difference in detection of rectal HCV between men with acute or chronic infection, and no correlation with the presence of rectal sexually transmitted infections or syphilis.

The researchers concluded that the quantities of HCV detectable in rectal fluid would be sufficient for HCV transmission to take place during anal intercourse, even without the presence of blood. HCV might also be transmitted without the presence of blood during group sex, for example on the penis of the active partner, on sex toys, through fisting or through use of douching equipment, even when condoms or gloves are used.

The results of both studies led the authors to recommend the use of condoms for anal intercourse to men with HIV.

HCV Also Present in Feces

An unrelated German study also presented at the Liver Meeting showed that HCV is present in feces, leading the authors to suggest that contact with feces may be a route of transmission, at least in men.

The study analyzed stool samples from 98 men and women with HCV monoinfection for the presence of HCV RNA. 68 samples were positive for HCV RNA (69%) but blood was present in only 5 of these samples. HCV was detected significantly more often in the stool samples of men compared with women (83% vs 52%) and in people with low platelet counts.

11/16/15

References

AL Foster, M Gaisa, RM Hijdra, DS Fierer, et al. Rectal Shedding of HCV in HCV/HIV Co-infected Men. AASLD Liver Meeting 2015. San Francisco, November 13-17, 2015. Abstract 89.

S Turner, M Yip, W van Seggelen, DS Fierer, et al. HCV in Semen of HIV-infected Men During Acute and Chronic Infection. AASLD Liver Meeting 2015. San Francisco, November 13-17, 2015. Abstract 1852.

B Heidrich, E Steinmann, I Plumier, H Wedemeyer, et al. HCV RNA and HCV core antigen are frequently detect- able in stool of men chronically infected with HCV: Is feces a potential source of infection? AASLD Liver Meeting 2015. San Francisco, November 13-17, 2015. Abstract 1002.