HIV

HIV & AIDS: The Basics

What’s the difference between HIV and AIDS? This is a confusing question for many people. Let’s break it down.

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Not everyone with HIV has AIDS. That's because HIV is a virus and AIDS is a medical condition caused by the virus after someone's been infected for awhile. 

Here are more precise definitions of HIV and AIDS, and the differences between them:

HIV stands for:

Human – Meaning only humans can contract this strain of the virus.
Immunodeficiency – Affecting the immune system and causing it to weaken.
Virus – A microorganism that replicates inside a host organism’s cell.

HIV is the virus that we know causes AIDS. It enters the body and infects immune system cells, as well as other cells in the body -- causing more copies of the virus to be produced.  A person who has been infected with HIV is HIV-positive, but does not necessarily have AIDS.

By contrast, AIDS stands for:

Acquired – It happens in people who already have been infected with HIV
Immune – Affecting the immune system
Deficiency – Weakening
Syndrome – A collection of symptoms that indicate a disease.

AIDS is a diagnosis given by a doctor. People get an AIDS diagnosis only when they meet a specific set of criterion. For example, their white blood cell (CD4+ cells) count is below 200 or they have been diagnosed with an opportunistic infection or cancer. Here is a full explanation of how doctors make an AIDS diagnosis.

In San Francisco..roughly 1 in 4 gay, bisexual, and transgender men have HIV. Of these, 20% are unaware that they are HIV-positive.  In 2008, there were 14,501 men living with HIV.  Of these men, 8,542 had at one point received a diagnosis of AIDS.