Human immunodeficiency virus (HIV for short) is the virus that causes AIDS (acquired immunodeficiency syndrome). AIDS is a serious, life-threatening illness that has a variety of symptoms. HIV infection can be treated with medications to make patients feel better and to prolong life. However, there is no cure for HIV infection or AIDS. Approximately 40 million people are infected with HIV worldwide. The August 16, 2006, issue of JAMA is dedicated to HIV/AIDS. This Patient Page is adapted from one previously published in the July 14, 2004, JAMA HIV/AIDS theme issue.