What Is The Difference Between HIV And AIDS?

The term AIDS refers to an advanced stage of HIV infection, when the immune system has sustained substantial damage. Not everyone who has HIV infection develops AIDS.

When HIV progresses to AIDS, however, it has proved to be a universally fatal illness. Few people survive five years from the time they are diagnosed with AIDS, although this is increasing with improvements in treatment techniques.

Experts estimate that about half the people with HIV will develop AIDS within 10 years after becoming infected. This time varies greatly from person to person, however, and can depend on many factors, including a person's health status and health-related behaviors.

People are said to have AIDS when they have certain signs or symptoms specified in guidelines formulated by the U.S. Centers for Disease Control and Prevention (CDC).

The CDC's definition of AIDS includes:

• All HIV-infected people with fewer than 200 CD4+ T cells per cubic millimeter of blood (compared with CD4+ T cell counts of about 1,000 for healthy people)
• People with HIV infection who have at least one of more than two dozen AIDS-associated conditions that are the result of HIV's attack on the immune system

AIDS-associated conditions include:

• Opportunistic infections by bacteria, fungi, and viruses. Opportunistic infections are infections that are rarely seen in healthy people but occur when a person's immune system is weakened.
• The development of certain cancers (including cervical cancer and lymphomas).
• Certain autoimmune disorders.

Most AIDS-associated conditions are rarely serious in healthy individuals. In people with AIDS, however, these infections are often severe and sometimes fatal because the immune system is so damaged by HIV that the body cannot fight them off.