The virus that causes Hepatitis C (HCV) can be sexually transmitted and the risk is directly related to the frequency of intercourse, the findings from a new study suggest. However, the association does not seem to be very strong.

Contact with infected blood is the main route by which HCV is transmitted, lead author Dr. Veysel Tahan, from Marmara University in Istanbul, Turkey, and colleagues note. However, in up to 50 percent of cases, a transmission route is never identified.

Researchers have hypothesized that some of these unknown cases may be caused by sexual transmission. To investigate this controversial topic, Tahan’s team assessed HCV transmission between 600 patients with chronic hepatitis C and their spouses.

In a subgroup of 216 spouses who were HCV-negative at the start of the study, the authors assessed transmission rates over an average period of 36 months. The findings appear in the current issue of the American Journal of Gastroenterology.

Antibodies against HCV, indicating exposure to the virus, were detected in two percent of the spouses, the researchers note. The average age and duration of marriage were not associated with the likelihood of detecting HCV antibodies.

In contrast, an association between the frequency of sexual intercourse and HCV transmission risk was observed. However, this relationship was not statistically significant, indicating the association was.

In the subgroup of 216 spouses, none of the HCV-negative subjects became positive during follow-up, the investigators note.

“The risk of HCV transmission between monogamous sex partners may be related to the number of sexual intercourse” events, the authors state. “The absence of any evidence of transmission in the three-year follow-up period suggests that this relation is not very strong.”

In a related editorial, Dr. Norah A. Terrault, from the University of California at San Francisco, comments that the “low incidence of new infections among monogamous couples supports the clinical practice of not recommending that such couples change their sexual practices.”

SOURCE: American Journal of Gastroenterology, April 2005.