HIV and AIDS: How They’re Different

HIV and AIDS are related, but they’re not the same.


HIV is a virus. It may lead to AIDS, the disease you can get after the virus has infected your body for several years and has weakened your immune system.

Not everyone who has HIV will get AIDS, but without treatment with antriretroviral drugs the infection will progress to AIDS. That usually happens in 10-15 years, according to the World Health Organization.

Many people with the virus don’t know they have it.  Of the approximately 1.1 million people infected with HIV in the U.S., about 160,000 have not been diagnosed and are therefore unaware of their HIV infection. They cannot be treated effectively until their infections are diagnosed by a blood test and they see a doctor. 

There are about 38,000 new cases of HIV infection each year in the U.S.

Worldwide, there were 36.7 million cases of HIV in 2016.

HIV: The Basics

HIV stands for “human immunodeficiency virus.”

“Immunodeficiency” means the systems that fight illnesses in your body aren’t working.

Your immune system has cells called CD4 or T cells that help keep you healthy. HIV attacks these cells. The virus copies itself over and over, reducing the number of CD4 cells in your body. Without that armor, you become more vulnerable to infections from bacteria and viruses. Antiretroviral drug therapy stops the destruction of CD4 cells. 

You can get HIV from direct contact with:

Most commonly, the virus is passed from person to person by:

  • Sex
  • Sharing needles
  • Mother-to-baby infection during pregnancy

People with a new HIV infection often say they feel like they have the flu. Early symptoms include:

If you have such symptoms and you might have been recently exposed to HIV, you should see a doctor to get tested for HIV.

AIDS: The Basics

AIDS stands for “acquired immunodeficiency syndrome.” HIV can become this disease if it’s not treated.

About 1.1 million people in the U.S. have HIV infection. About 18,000 were diagnosed with AIDS in 2016. It's the third, and most advanced stage of the infection.  Persons who develop AIDS were either never diagnosed with HIV infection or were otherwise not treated with HIV drugs early enough to prevent progression to AIDS.


When you have HIV, your doctor will watch the amount of the virus in your system. You may hear this amount called your “viral load.” Two things will tell your doctor if it has become AIDS:

Your CD4 count.  A healthy immune system has a CD4 count of 500 to 1,600. A person with AIDS has a CD4 count below 200.

AIDS-defining infections.  They’re also called opportunistic infections. These generally occur in persons with a CD4 count below 200. Viruses, bacteria, or fungi that don’t usually make healthy people sick can cause these infections in someone with HIV.

The amount of time it takes for HIV to become AIDS is different for everyone. Without treatment, you can live with the virus for 10-15 years before getting AIDS. With treatment you may never develop AIDS.

Once you have AIDS, you have it. But you can live a long time with antiretroviral treatment.

Warning signs that you may have AIDS include:

  • Sudden weight loss
  • Night sweats
  • Fever that keeps coming back
  • Feeling very tired for no reason
  • Diarrhea that lasts for more than a week
  • Sores in your mouth, in your anal area, or on your genitals
  • Pneumonia
  • Blotches on your skin or inside your mouth, nose, or eyelids
  • Memory loss
  • Depression


More than 25 drugs are approved to treat HIV. You may hear them called “antiretroviral drugs.” Your doctor will prescribe a combination of these medications as antiretroviral therapy, or ART. 

The medicines you take will help keep the virus from making copies of itself. That will keep you healthy and also lower your risk of spreading HIV to others.

The goal of ART is to lower your viral load. It won’t cure your HIV, but with the right medicine, the amount of the virus in your blood may drop below a detectable level and stay that way for a long time.

Stick to your treatment plan, because people with the virus are living longer and better than ever.


WebMD Medical Reference Reviewed by Jonathan E. Kaplan, MD on February 20, 2018



Office on Women’s Health: “How is AIDS different from HIV?” and “Opportunistic Infections and Other Conditions.”

CDC: “HIV/AIDS: Statistics Overview;” “Act Against AIDS: Basic Statistics;” and “HIV in the United States: At a Glance.”

Medline Plus Medical Dictionary: “Immunodeficiency.” “HIV Lifecycle.”

New York University Institute of Human Development and Social Change Center for Health, Identity, Behavior and Prevention Studies: “HIV/AIDS Info.”

National Institute of Allergy and Infectious Diseases: “HIV/AIDS.”

Department of Health & Human Services AIDSinfo: “HIV Overview” and “HIV Treatment.”

The Foundation for AIDS Research: “Thirty Years of HIV/AIDS: Snapshots of an Epidemic.”

World Health Organization: "HIV/AIDS."

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