Acquired immunodeficiency Syndrome (AIDS) is caused by infection with Human Immunodeficiency Virus (HIV). After invading the body, HIV gradually damages the immune system and destroys white blood cell. Symptoms of HIV infection may not be recognized for 10 years or even longer.

Eventually the breakdown of the immune system will occur and the infected person becomes fatally vulnerable to cancer and diseases that healthy people rarely suffered from (named “Opportunistic Infection”). Common “Opportunistic Infection” may attack the skin, mouth, lung, eyes, organs or brain, such as Tuberculosis and Pneumocystis carinii etc.

HIV is transmitted when blood, semen or vaginal secretions are passed from an infected person into the body of another person. The common routes are unprotected sex (both vaginal and anal), sharing of needles, mother-to-baby and unscreened blood transfusions.