Blood borne viruses (BBVs) are viruses that some people carry in their blood and can be spread from one person to another. Those infected with a BBV may show little or no symptoms of serious disease, but other infected people may be severely ill. You can become infected with a virus whether the person who infects you appears to be ill or not – indeed, they may be unaware they are ill as some persistent viral infections do not cause symptoms. An infected person can transmit (spread) blood borne viruses from one person to another by various routes and over a prolonged time period.
The most prevalent BBVs are:
Other viruses that cause hepatitis (such as hepatitis A and E) are not usually passed on by blood-to-blood contact and hence do not present a significant risk of blood-borne infection. The hepatitis D virus, previously known as the 'delta agent', is a defective virus, which can only infect and replicate in the presence of HBV.