Human Immunodeficiency Virus (HIV) appeared in the blood supply in the early 1980's. HIV infects and over a period of time destroys the body's immune system. Initially, an HIV infectee may appear to have no symptoms.
Acquired Immunodeficiency Syndrome (AIDS) is a term used to describe the point at which an infected person's immune system no longer functions and opportunistic infections such as pneumonia begin to occur. People die from the diseases the immune system cannot fight rather than the AIDS virus itself.
Symptoms can appear from as soon as six weeks post infection.
HIV works by destroying a white blood cell known as CD4 T cells. The lower the CD4 count is, the more likelihood there is of opportunistic infections occurring although the danger level is thought to begin when the CD4 count is around 200 or less. The opportunistic infections can include thrush, eye infections and herpes to name but a few.
Patients are monitored on a regular basis at a specialist HIV clinic. Samples of blood are taken to measure the viral load (how much virus is present) and the CD4 count which shows the level of T cells present in the blood.
Modern treatment usually consists of a combination of antiretroviral drugs in tablet form. By attacking the HIV cells in different ways they can supress the viral load and allow the CD4 count to rise which in turn protects the body's immune system.
In the space of about seven years, from 1985 and 1992, before full development of anti-retroviral treatment, HIV brought about the tragic deaths of 403 of the 1,200 haemophiliacs who contracted HIV. Around 400 more died in the next twenty years.