For the computer virus, see AIDS (MS-DOS).HIV virus going out of a cell**Acquired immunodeficiency syndrome** or **Acquired immune deficiency syndrome** (**AIDS**) is a disease caused by a virus called HIV.

* *Acquired* means that people are not born with the disease. They get it after being infected with the HIV virus.
* *Immune* or *Immuno-* talks about the immune system. The immune system is the part of the body that fights off disease.
* *Deficiency* means not to be enough. An *immuno-deficiency* is a problem where the immune system is damaged and cannot fight off diseases to keep the body healthy.
* *Syndrome* is a collection of symptoms, or problems in the body. Because the immune system is damaged, and cannot fight off disease, people with AIDS get a collection of symptoms which is referred to as the "Acquired Immunodeficiency Syndrome."

How many people have AIDS?
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As of 2018, it is estimated that there are 39.7 million people worldwide infected with HIV. The HIV pandemic is most severe in Sub-Saharan Africa. Over 60% of all people with HIV live in the region.

Many people with HIV do not know they have it. Because of this, the exact number of people with HIV is unknown.

Where HIV started
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Scientists believe the first human who got HIV was a person in Africa in the early 1900s. It infected only a small amount of people (disease not recognised), until it then turned into an epidemic reported to have started in New York (USA) in 1981. It then very quickly started spreading to other countries. This happened when **S**imian **I**mmunodeficiency **V**irus (SIV) went from apes or chimpanzees to humans. This virus probably crossed to humans when a hunter came into contact with monkey blood while cutting up monkeys to eat. Research in October 2014 shows that the virus started in Kinshasa during the 1920s. It was quickly spread by unprotected sex, dirty needles used by intravenous drug users, and it then made its way into the medical blood supply. Some people described the spread of the disease as a *sexidemic* (widespread).

HIV and AIDS
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Not everyone who has HIV has AIDS. When people first get HIV, they can be healthy for years. A person is diagnosed as having AIDS when he or she gets specific types of illnesses or gets sick in certain ways due to their HIV. Once a person's HIV progresses to (or turns into) AIDS, the person will continue to have AIDS for the rest of their life. While there are many treatments for HIV/AIDS, at this point there is no cure.

If someone has HIV they are called *HIV-positive*.

Someone has AIDS if they have HIV and either:

* Blood tests that show very low numbers of white blood cells – special cells that fight infections
* AIDS defining illnesses (illness is another word for disease.)

### AIDS-defining illnesses

If a person gets an "AIDS-defining illness," this is usually a sign that the person has AIDS. Healthy people do not get these illnesses, because a healthy immune system is strong enough to fight off these diseases. Because of this, getting an AIDS-defining illness is a sign that a person's immune system is seriously damaged. In a person with HIV, getting an AIDS-defining illness signals that the HIV has damaged the immune system badly enough that the person now has AIDS.

Some AIDS defining illnesses are:

* Kaposi's sarcoma – a type of cancer that usually affects the skin (often causing red or purple lesions, or wounds, on the skin). Sometimes KS only affects the skin; sometimes it also affects other systems in the body.
* CMV retinitis – a virus that infects the back of the eye.
* Pneumocystis carinii pneumonia (acronym PCP) – a type of pneumonia, an infectious disease of the lung. PCP is the most common infection in AIDS patients.
* Toxoplasmosis – a parasitic disease (a disease caused by a parasite), which can cause problems in the brain as well as other systems in the body.
* Invasive cervical cancer – cancer of the bottom part of a woman's uterus. Invasive means the cancer has spread.

### How is HIV spread?

HIV can be spread by some body fluids that have HIV in them:

* Blood
* Semen
* Fluids from a woman's vagina
* Fluids from the rectum
* Breast milk
* From infected mother to child during pregnancy (Transplacental).

This means a person can get HIV by:

* Having sex with a person with HIV without using condoms or other types of protection
	+ This includes anal sex and (sometimes) oral sex
* Sharing needles with someone who has HIV (to inject illegal drugs like heroin)
* Getting stuck with a needle that has been used on someone with HIV (this happens sometimes to healthcare workers like doctors and nurses)
* A mother with HIV can pass HIV on to her baby while she is pregnant or if she breast-feeds the baby

### How is HIV not spread?

HIV is NOT spread by:

* Body fluids like saliva (spit), tears, or sweat
* Touching a person with HIV (like shaking hands or hugging)
* Sharing dishes or drinking from the same glass as someone with HIV
* Light switches or toilet seats
* Drinking fountains
* Air or water
* Insects, like mosquitoes

Treatment
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There are medicines that help people with AIDS. These are called *antiretroviral* medicines (or *antiretrovirals*.) Anti- means against. HIV is a retrovirus. So *antiretroviral* means it fights retroviruses.

Antiretrovirals cannot cure AIDS. This means they cannot make all of the virus leave a person's body. But they can make people with AIDS more healthy. Antiretrovirals help people fight the HIV virus. This makes their immune systems work better. So antiretrovirals are a *treatment* but not a *cure* for HIV.

People with HIV/AIDS who take antiretroviral medicines live longer. They live longer without getting *AIDS defining illnesses*. But after a long time, the HIV virus learns how to fight the antiretrovirals. The HIV virus is not killed by this medicine. HIV becomes *resistant* to the medicine. Then the *resistant* HIV hurts the immune system and the person may get AIDS.

Sometimes when HIV is resistant to one medicine, another medicine can be used. To make less resistance happen, people with AIDS take more than one medicine at the same time. They may take 2–4 medicines at once. This is sometimes called a *cocktail* or *AIDS cocktail*.

When HIV gets resistant to one medicine, this is changed to another medicine. So the *AIDS cocktail* that people with AIDS take changes over time. But after a long time, the HIV learns to be resistant to *many* drugs. This is called *multi-drug-resistant* (acronym MDR) HIV. After the HIV in a person has MDR-HIV there may be no more medicines to treat them. So scientists keep trying to find new medicines to fight HIV.
The five most important HIV medicines are:

* D4T (stavudine)
* 3TC (Lamivudine)
* NVP (nevirapine)
* AZT (zidovudine)
* EFZ (efavirenz)

HIV orphans
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Percent of people with HIV in Africa in 1999–2001
Many people who die of AIDS, especially in Africa, leave behind children who are still alive, and may need help. These children are called AIDS orphans.

Ways to stop AIDS
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There are many ways people fight the *AIDS epidemic*.

### Education

The most important way to stop HIV/AIDS is education. People can get HIV from the exchange of bodily fluids and from sharing needles. Children can also get HIV from their mothers (when they grow inside pregnant mothers and when they drink breast milk.)
Sex is one way to get HIV. If people use condoms when they have sex, there is a much smaller chance of catching HIV.

A person can also get HIV by *sharing needles*. This means using a needle that has not been cleaned after someone else has used it. Some people who take illegal drugs like heroin and cocaine take these drugs by needle. Some of these people share needles. If one person has HIV and he shares his needles, he can give HIV to other people. But if people have clean needles or if they know how to clean needles, they do not get HIV as much.

Many people do not know that condoms and clean needles help stop HIV. They may not even *know* that sharing needles and sex with someone who has HIV can make them get HIV. Even if people know about condoms and clean needles, they may not *have* condoms and clean needles.

### Safe sex and needle exchange

There are some people who do not want people to *know* about condoms or clean needles. They believe that if people know about condoms and have condoms they will have more sex. They believe that if people have clean needles they will use illegal drugs more. Many of these people think this because of their religion. For example, the Catholic church does not want people to have or use condoms. They do not want people to have condoms because they do not think people should have sex unless they are married. They also think that married people should not use condoms, because they believe that if people have sex, they should be prepared to accept a possible pregnancy.

Scientists who study (look at and learn about) people who use condoms, see that if teenagers (children 13–19) learn about condoms (and other birth control) they have *less* unsafe sex. Scientists see that learning about these things does not make teenagers start having sex earlier. The teenagers also have *safer* sex. Safer sex means doing things (like wearing condoms) to try not to get pregnant or get sexually transmitted diseases (STDs or STIs) like HIV, gonorrhea, and syphilis. Using a condom works ***very*** well for keeping people from getting pregnant or getting STDs if people know how to use a condom the right way. 

Scientists have also learned that if a city has a needle exchange program it will have fewer people who use illegal drugs. *Needle exchange programs* are where people can come in and trade dirty needles for clean needles. This means that *if* they use drugs they will be more safe. But needle exchange programs do more than give people clean needles. They teach people about drugs. If people want to stop using drugs, they help them.

### HIV vaccine

The best way to stop HIV is thought to be a vaccine. There is no vaccine for HIV yet. Many scientists are looking for an HIV vaccine. Even one that protected some people from HIV would save millions of people's lives.

Wrong ideas
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Some people think that HIV is not the cause of AIDS. They dispute the connection between HIV and AIDS, the existence of HIV itself, or the validity of HIV testing and treatment methods. These claims, known as "AIDS denialism", are rejected by the scientific community. However, they have had a significant impact, particularly in South Africa. There the government's official embrace of AIDS denialism (1999–2005) was responsible for its weak response to that country's AIDS epidemic. It has been blamed for hundreds of thousands of avoidable deaths and HIV infections.

Some conspiracy theories have been put about. Operation INFEKTION was a worldwide Soviet active measures operation to spread the claim that the United States had created HIV/AIDS. Surveys show that a significant number of people believed – and continue to believe – in such claims.

Other websites
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* World Health Organizations 3 by 5 Initiative
* Médecins Sans Frontières: Campaign for Access to Essential Medicines Archived 2005-08-12 at the Wayback Machine
* WHO HIV/AIDS Programme
* AIDS Education Global Information System
* From the US National Institutes of Health Archived 2021-03-22 at the Wayback Machine
* New England Journal of Medicine Article "Patents versus Patients? Antiretroviral Therapy in India" Archived 2009-05-01 at the Wayback Machine
* AIDSPortal knowledge network
* Piedmont Care
* AIDS portal Archived 2010-01-19 at the Wayback Machine