Transmission of Hepatitis C

Hepatitis C is a disease with a significant global impact. According to the World Health Organization there are 170 million people infected with hepatitis C virus (HCV). There are considerable regional differences. In Europe and the United States chronic hepatitis C is the most common chronic liver disease. The majority of liver transplants performed in these regions are for chronic HCV. It is difficult to determine the number of new HCV infections, as most acute cases are not noticed clinically.

Parenteral exposure to the hepatitis C virus is the most efficient means of transmission. The majority of patients infected with HCV in Europe and the United States acquired the disease through intravenous drug use or blood transfusion, which has become rare since routine testing of the blood supply for HCV began. The following possible routes of infection have been identified in blood donors (in descending order of transmission risk):

• Injection drug use
• Blood transfusion
• Sex with an intravenous drug user
• Having been in jail more than three days
• Religious scarification
• Having been struck or cut with a bloody object
• Pierced ears or body parts
• Immunoglobulin injection

Very often in patients with newly diagnosed HCV infection no clear risk factor can be identified.

Factors that may increase the risk of HCV infection include greater numbers of sex partners, history of sexually transmitted diseases, and failure to use a condom. Whether underlying HIV infection increases the risk of heterosexual HCV transmission to an uninfected partner is unclear. The seroprevalence of HCV in MSM (men who have sex with men) ranges from about 4 to 8%, which is higher than the HCV prevalence reported for general European populations.

The risk of perinatal transmission of HCV in HCV RNA positive mothers is estimated to be 5% or less (Ohto 1994). Caesarean section has not been shown to reduce transmission. There is no evidence that breastfeeding is a risk factor.

Hemodialysis risk factors include blood transfusions, the duration of hemodialysis, the prevalence of HCV infection in the dialysis unit, and the type of dialysis. The risk is higher with in-hospital hemodialysis vs peritoneal dialysis.

Contaminated medical equipment, traditional medicine rites, tattooing, and body piercing are considered rare transmission routes.

There is some risk of HCV transmission for health care workers after unintentional needle-stick injury or exposure to other sharp objects.