AIDS is caused by the Human immunodeficiency virus, more commonly known as HIV. This virus attacks the immune system, leaving the body vulnerable to a wide range of infections and diseases. Common bacteria, parasites and viruses that would not originally cause serious disease in people could be potentially fatal for people with AIDS. AIDS is the fifth most common leading cause of death for people between the ages of 25 and 44 in the United States. In 1995, it was the number one cause of death. About 25 million people worldwide have died from this infection, with over 40 million people currently living with either HIV or AIDS as of 2008.
