Are HIV and AIDS the Same Thing?

Definition and Difference Between HIV and AIDs.

HIV virus particle
HIV virus particle. Getty Images/Science Photo Library - MEHAU KULYK/Brand X Pictures

In the media, you often hear the terms HIV and AIDS used interchangeably. But the fact of the matter is that HIV and AIDS are not the same thing. How do they differ? How are the connected? Let's take a closer look at the definition of and difference between HIV and AIDS.

What is HIV?

HIV stands for human immunodeficiency virus. It originates from a chimpanzee-related immunodeficiency virus in West Africa that gradually spread to humans throughout the world. Scientists theorize that HIV has existed in the United States since the mid to late 1970s.

Once infected with HIV, a person will have the virus in their body forever. While there currently is no cure for HIV, it can be controlled with HIV medication.

How Does HIV Weaken a Person's Immune System?

HIV lives in a person's body and attacks T-cells, which are a type of blood cells in the immune system used to fight infection. These T cells are also known as CD4 cells — so a person with HIV without treatment will gradually have a decline in the number of their T cells or CD4 counts.

As the CD4 counts get lower and lower, a person becomes unable to fight off dangerous infections. These infections that occur as a result of HIV are called opportunistic infections. Examples of common opportunistic infections include:

-- Parasitic opportunistic infections, like cryptosporidiosis or isosporiasis — causes diarrhea

-- Wasting syndrome due to HIV — causes significant loss of muscle mass

-- Kaposi's sarcoma — a cancer caused by a virus 

More on opportunistic infections can be found at Opportunistic Infection Fact Sheets

What is AIDS?

AIDS stands for acquired immunodeficiency syndrome and is caused by HIV.

A person develops AIDS when their HIV progresses— it's like the final stage of HIV. A person has AIDS when:

-- their CD4 cells fall below 200 (Normal CD4 count is between 500 and 1600)

-- they develop one or more opportunistic infections, regardless of their CD4 count 

How Can A Person Prevent HIV from Developing into AIDS?

HIV treatment or antiretrovirals can reduce the amount of virus in the body. This will prevent the CD4 cells from being depleted, which will boost a person's immune system — preventing the development of opportunistic infections. 

It's important to note that once a person develops AIDS, they always have AIDS. This remains true even if their CD4 counts go back up, or they get better from the opportunistic infection that initially defined their AIDS.

Also, not everyone with HIV gets AIDS. 

What Can I Do?

The most important thing you can do is to get tested for HIV if you are unsure of your status. If you do have HIV, seek care from an HIV specialist so you can get started on therapy before your disease advances. 

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