Acquired immunodeficiency syndrome (AIDS) is a fatal disease in which the immune system is weakened by the human immunodeficiency virus or HIV. It is often referred to as HIV/AIDS. A healthy immune system fights off infections and certain diseases. HIV is a serious infection that progressively kills or impairs immune system cells. AIDS is not a single disease; it covers a wide range of symptoms and illnesses that can occur when the HIV virus becomes advanced enough to severely deplete the immune system. People who have AIDS can develop a variety of illnesses that are life-threatening.

AIDS was first recognized in the United States in 1981 and is now considered a worldwide epidemic. Anyone can get AIDS. In the United States, it is considered one of the most devastating public health problems in recent history. In 1998, the Centers for Disease Control and Prevention (CDC) estimated that 650,000 to 950,000 Americans...