HIV (Human Immunodeiciency Virus) is a virus. You may hear that someone is HIV infected, has HIV infection, or has HIV disease. These are all terms that mean the person has HIV in his or her body and can pass the virus to other people.

HIV attacks the body’s immune system. The immune system protects the body from infections and disease, but has no clear way to protect it from HIV. Without treatment, most people infected with HIV become less able to ight off the germs that we are exposed to every day. Many of these germs do not usually make a healthy person sick, but they can cause life-threatening infections and cancers in a person whose immune system has been weakened by HIV. HIV treatments can slow this process and allow people with HIV to live longer, healthier lives (see question 66).

People infected with HIV may have no symptoms for ten or more years. They may not know they are infected. An HIV test is the only way to ind out if you have HIV.

AIDS (Acquired Immune Deiciency Syndrome) is a late stage of HIV disease. According to the Centers for Disease Control and Prevention (CDC), a person with HIV infection has AIDS when he or she:

• has a CD4 cell count (a way to measure the strength of the immune system) that falls below 200. A normal CD4 cell count is 500 or higher.

OR

• develops any of the speciic, serious conditions – also called AIDS-deining illnesses – that are linked with HIV infection (see Appendix for a list of these conditions).