Acquired immune deficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV). HIV progressively decreases the effectiveness and resiliency of the immune system, and as a result, infected individuals become susceptible to opportunistic infections such as pneumonia, tuberculosis, Kaposi's sarcoma, and other infections normally fought off by the immune system.

AIDS is now a global pandemic. By 2001, AIDS was the world's fourth leading cause of death, after heart disease, stroke, and acute respiratory infection. With the release of the World Health Organization's (WHO) and UNAIDS World AIDS report 2008, it was estimated that 33.2 million people are living with the disease worldwide, with an annual AIDS death toll hovering around 2 million people.

While AIDS is a worldwide ...