What are blood-borne viruses?

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:

• human immunodeficiency virus (HIV)- a virus which causes acquired immunodeficiency virus (AIDS), a disease affecting the body's immune system;
• hepatitis B (HBV) and hepatitis C; BBVs causing hepatitis, a disease affecting the liver.

As well as through blood, these viruses can also be found and transmitted through other body fluids, for example:

• vaginal secretions;
• semen; and
• breast milk.

Unless contaminated with blood, minimal risk of BBV infection is carried by:

• urine;
• saliva;
• sweat;
• tears;
• sputum;
• vomit; and
• faeces.

The presence of blood in these bodily fluids and materials isn't always obvious, so care should still always be taken to avoid infection.

Blood-borne viruses covered in this guidance

Further details

Blood-borne viruses that cause hepatitis include the hepatitis B virus (HBV) and hepatitis C virus (HCV). 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.

The number of occupational exposure incidents relating to blood or other high-risk body fluids are collated and reported bi-annually by the Health Protection Agency (HPA) in their Eye of the Needle report.