The hepatitis C virus (HCV) is most commonly transmitted through contaminated blood and enters the body through damaged skin or mucous membranes. In most cases transmission occurs through the sharing of injection equipment during intravenous use, less commonly through snorting and freebasing, tattooing or, very rarely, through the shared use of razors or toothbrushes. The possibility of mother-to-child transmission during delivery is 5%. The risk of being infected through a blood transfusion in Switzerland is practically nil.

The incubation period is between 20 days and 6 months. A majority of those infected and those left untreated will be contagious within one to several weeks after the illness emerges. In most cases, a hepatitis C infection progresses asymptomatically. Only between 10% and 20% of those affected develop acute hepatitis, which can manifest with flu-like symptoms such as headaches or aching limbs, fatigue, fever, loss of appetite or nausea, abdominal pain, darkened urine or jaundice (yellowing of the white of the eye and the skin). In 70%–80% of those cases, the infection becomes chronic, i.e., it doesn’t heal spontaneously within 6 months. Roughly 5%–30% of those affected develop cirrhosis of the liver (scarring of the liver tissue) as a result. Chronic untreated hepatitis C infections are the most common cause of liver cancer and liver transplantations in Switzerland. Those affected also have an increased risk of complications such as diabetes or cardiovascular disease.