Return to: Get the Facts
Human Immunodeficiency Virus—HIV—is the virus that causes AIDS. HIV takes over white blood cells. This disables the immune system, which otherwise keeps the body healthy by fighting off viruses, bacteria and other organisms that cause illness. Many people with HIV have no symptoms and are unaware of their own status.
Acquired Immune Deficiency Syndrome—AIDS—is a condition in which the HIV virus has impaired the immune system, making the body vulnerable to certain diseases known as opportunistic infections. In a person with an uncompromised immune system, such diseases do not have the same opportunity to take hold. A person is considered to have AIDS if he/she is HIV-positive and has developed one or more illnesses associated with AIDS (as defined by the Centers for Disease Control and Prevention) or has a white blood cell count of less than 200.