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Often, the terms HIV and AIDS are used interchangeably, leading to confusion about their differences. Here, we’ll discuss the definition and differences of both terms.

HIV stands for ‘human immunodeficiency virus’. HIV belongs to a group of viruses called retroviruses. HIV attacks white blood cells within the immune system. These cells will stay infected for the rest of their lives. If untreated, HIV will develop into AIDS.

AIDS stands for ‘acquired immune deficiency syndrome’. (It’s sometimes referred to as ‘late stage HIV’ or ‘advanced HIV disease’.) It is an umbrella term for the illnesses that occur due to having untreated HIV infection for several years, by which point the immune system is severely damaged and unable to fight off infections. The illnesses and symptoms will vary for each person that has AIDS, but may include life-threatening infections and cancers.

Every person who has AIDS has HIV, but not every person with HIV will develop AIDS. Because there are now lots of treatment options available for people living with HIV, far fewer people are developing AIDS. Often, those that do develop AIDS are people who have not been tested for HIV and have never taken treatment. Once started on HIV treatment, death due to AIDS can be prevented.

The only way to find out if you have HIV is to get tested for the virus. There is no test for AIDS as it is a collection of infections and illnesses that occur because of untreated HIV infection. Often, people can experience a range of them before HIV is discovered to be the cause. This is why AIDS is sometimes difficult to diagnose. 

Ultimately, HIV is a virus that attacks the immune system and AIDS is a term that can only be used when HIV has caused severe damage to the immune system.

Mercy Shibemba

Mercy Shibemba

Article author

Mercy is an award-winning activist and advocate for children and young people living with HIV. Sharing her story of growing up with HIV to educate, challenge and inspire. She works on youth engagement and participation across clinical trials, research and charities that support young people. She is also the Chair of The Social Innovation Partnership. 

Basic information

Better off knowing

Better off knowing

Testing

Testing basics leaflet.

Where can I get an HIV test?

A person having a blood test. They are sitting in a chair while a nurse collects blood in a vial.

How do I know if I have HIV?

A person wearing a surgical glove holds the hand of somebody else. This person is having their finger pricked with a fine needle. The needle has drawn a small amount of blood which is visible. The image has a pink and purple filter over it.

What are the symptoms of HIV?

Domizia Salusest | www.domiziasalusest.com

Is HIV man-made?

An illustration of an HIV virus.

Is HIV a death sentence?

A man stands in a doorway smiling.

Very recent infection

Very recent infection

Myths and facts

Myths and facts

What does undetectable mean?

HIV testing

A close-up of a glass receptacle which contains a testing vial. This vial is labelled as being ready to receive blood for an HIV test. The image has a pink and purple filter over it. The image has a pink and purple filter over it.

Early HIV infection

A woman site on the sofa with a blanket over her and around her shoulders.

What are the symptoms of early HIV infection?

A woman is resting in bed.

Where did HIV come from?

Democratic Republic of the Congo. Image by Christina Bergey. Creative Commons licence.