Acquired Immune Deficiency Syndrome or AIDS is caused by Human Immunodeficiency virus (HIV)-a retrovirus. HIV infects T-helper cells, a type of T-lymphocyte which helps both B-lymphocytes (which produce antibodies) and other T-lymphocytes (which kill cells infected by viruses) to carry out their functions. Neither type of lymphocyte can therefore operate and so the body’s immune system is rendered ineffective, not only against HIV but other infections. Hence, AIDS victims are frequently killed usually within two years of developing the disease by opportunist organisms which take advantage of impaired resistance.
Once infected with HIV an individual is said to be HIV positive a condition which persists throughout their life. As the virus remains dormant for about 8 years, on average, an HIV positive person does not suffer any symptoms during this period but can act as a carrier often unwittingly spreading the disease. The virus can be detected in virtually all body fluids of an HIV positive individual. However, since it is only in blood, semen or vaginal fluid that the concentration is high enough to infect others, it is spread through sexual intercourse or transfer of infected blood from one person to another sharing a hypodermic needle or from mother to baby during child birth. Faeces, urine, sweat, saliva and tears have such a low incidence of HIV in an infected person that contact with these presents practically no risk of contacting AIDS. Risk from contaminated clothing etc is negligible as virus quickly dies outside human body.
There is presently no cure for HIV. A drug currently under test Zydovudine (AZT) holds some hope.