Hepatitis C is a chronic infection caused by hepatitis C virus, or HCV, which is carried in the blood. In the U.S., most cases of HCV infection happen when drug users share needles with an infected person, and thus have direct blood-to-blood contact. The chances of catching HCV through unprotected sex are thought to be slim, but some studies have shown that if sexual acts are associated with blood exposure, sexual transmission of the virus could be possible.
University of Washington Assistant Professor Dr. Chia Wang, along with colleagues including VIDD associate member Dr. Keith Jerome and VIDD co-director Dr. Larry Corey, wondered whether menstruation might increase the chances of sexual transmission of HCV. To test this theory, they looked for the presence of HCV in 701 vaginal swabs from 16 HCV-positive women, taken daily over 56 days. Three of these women had had hysterectomies, six were post-menopausal, and seven were pre-menopausal. The researchers found no virus present in the swabs from women with hysterectomies, and found that virus was most likely to be present in pre-menopausal women on the days they were menstruating. However, HCV was rare in vaginal fluid overall, appearing in only 4 percent of the swabs the scientists tested. These findings suggest that sexual transmission of HCV from an infected female partner may be more likely during menstruation, but the overall risk of transmitting HCV during sex is low.
Wang CC, Cook L, Tapia KA, Holte S, Krows M, Bagabag A, Santos A, Corey L, Jerome KR. Cervicovaginal shedding of hepatitis C viral RNA is associated with the presence of menstrual or other blood in cervicovaginal fluids. J Clin Virol. 2010 Oct 14.