How is it passed on?

It is possible to have hepatitis C without knowing. You do not have to have symptoms to have the infection or to spread the virus. 

In about 10% of cases, the individual does not know how they became infected with the hepatitis C virus.1 However, it is important to be aware of the commonly known causes of infection to help you decide if you may be at risk.

The hepatitis C virus is spread by direct contact between infected blood and the blood or tissue  of a non-infected person. There are two major routes of transmission:

Blood transfusion and blood products (especially before 1992)

Hepatitis C was identified in 1989, but screening tests were not developed until a few years later.  Blood and blood products were not routinely screened for the hepatitis C virus before 1992, so you may have been exposed to the hepatitis C virus if you received a blood transfusion before 1992 (in the UK all blood and blood products have been screened since September 1991).  If you are concerned that you received a blood transfusion during this period and might be infected, contact your doctor for advice. 

Sometimes people don’t know if they have received a blood transfusion. You could have received a blood transfusion during:

  • Transplant surgery
  • Major surgery
  • Hospitalisation in intensive care
  • Haemorrhage (uncontrolled bleeding).

Blood and blood products used by doctors are now routinely screened for the hepatitis C virus in most countries and also undergo virus inactivation procedures where appropriate. Since the routine screening of blood for hepatitis C was introduced, there have been significantly fewer infections due to blood transfusions. If you have undergone any of the above procedures in countries of the developing world, where you suspect resources and healthcare infrastructure are insufficient to include screening procedures for blood, you should check to confirm if there was a screening programme in place for hepatitis C (and other blood-borne infections) in that country and consult your doctor to arrange for a test if appropriate.

Drug use (at any time)

Previous or current intravenous (injected) drug use is an important risk factor for transmission, even if it only happened once. Sharing a needle or syringe, or the material used to prepare the drug, could have led to the hepatitis C virus being transmitted.

Snorting cocaine is also a risk factor because it may cause corrosion of the nasal membranes, leading to nose-bleeds and the exposure of blood onto whatever is being used to inhale through (for example notes or straws).

Other causes

Contact with infected blood can also happen in the following situations:

  • Invasive procedures and other procedures where the skin is broken. This could happen if equipment has not been properly sterilised, cleaned or accidentally contaminated with blood, for example during:
    • Haemodialysis
    • Acupuncture
    • Tattooing or piercing
    • Shaving
    • Dentistry
    • Beauty treatments (for example hairdressers or barbers).
  • Re-use of equipment for invasive procedures and other procedures where the skin is broken is a major risk factor for hepatitis C. This can be a problem where resources are limited, particularly the re-use of syringes in the developing world.
  • Transmission from mother to baby during pregnancy.
    Only approximately 5% of women who have hepatitis C will pass the virus on to their child, and this probably happens during childbirth.2
  • Sexual transmission is very rare.

The risk of transmission through sexual intercourse may be higher when a woman is having her menstrual period, or if one of the partners has genital lesions. In all cases, people with hepatitis C who have more than one sexual partner should practise safe sex (using a condom). Those in stable heterosexual relationships with one partner do not normally need to change their current sexual practice.

1Alter MJ. Epidemiology of hepatitis C. Hepatology 1997; 26 (3 Suppl 1): 62S-65S.
2Newell ML, Pembrey L. Mother-to-child transmission of hepatitis C virus infection. Drugs Today (Barc) 2002; 38(5): 321-337.