A new study has found that couples having sex in a monogamous, heterosexual relationship do not get infected by hepatitis C virus (HCV).
Transmission of HCV from an infected partner during sex is rare according to the research.
Experts estimate that HCV affects up to 4 million Americans, most of whom are sexually active.
Medical evidence shows HCV is primarily transmitted by exposure to infectious blood, typically through intravenous (IV) drug use.
However, there are conflicting reports regarding sexual activity and HCV transmission with some studies suggesting that exposure to infected blood during sex-through bodily fluids such as vaginal secretions, semen or saliva-may carry a minimal infection risk.
"Generally the risk for transmitting HCV to sex partners is very low," lead study author Dr. Norah Terrault with the University of California, San Francisco said.
"Yet, lack of quantitative data about the risk of HCV transmission with sexual activity remains a limitation for doctors counseling their patients on safe sex practices," she said.
To specifically quantify the risk HCV transmission from a chronically infected individual to their sex partner, researchers recruited 500 anti-HCV-positive individuals, who were negative for the human immunodeficiency (HIV), and their long-term heterosexual partners.
Couples were surveyed about lifetime risk factors for HCV infection, sexual practices of the couple, and sharing of personal items.
The team analyzed blood samples to determine the presence or absence of active virus in the blood and compared the HCV strains in those couples with HCV present.
The majority of HCV infected individuals who participated in the study were non-Hispanic whites, had a median age of 49 years, and sexual activity with their partners ranging from 2 to 52 years.
HCV prevalence among partners was 4 percent, with 9 couples having similar viral strains and viral samples from 3 couples were highly related which is consistent with HCV transmission between the partners.
The research is published in Hepatology, a journal published by Wiley on behalf of the American Association for the Study of Liver Diseases (AASLD).