HIV (human immunodeficiency virus) is a virus that attacks the body’s immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). Learning the basics about HIV can keep you healthy and prevent HIV transmission. You can also download materials to share or watch videos on basic information about HIV.
What is HIV?
HIV (human immunodeficiency virus) is a virus that attacks the body’s immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome).
- There is currently no effective cure. Once people get HIV, they have it for life.
- But with proper medical care, HIV can be controlled. People with HIV who get effective HIV treatment can live long, healthy lives and protect their partners.
Where did HIV come from?
- HIV infection in humans came from a type of chimpanzee in Central Africa.
- The chimpanzee version of the virus (called simian immunodeficiency virus, or SIV) was probably passed to humans when humans hunted these chimpanzees for meat and came in contact with their infected blood.
- Studies show that HIV may have jumped from chimpanzees to humans as far back as the late 1800s.
- Over decades, HIV slowly spread across Africa and later into other parts of the world. We know that the virus has existed in the United States since at least the mid to late 1970s.
To learn more about the history of HIV in the United States and CDC’s response to the epidemic, see CDC’s HIV and AIDS Timeline.
How do I know if I have HIV?
The only way to know for sure whether you have HIV is to get tested. Knowing your HIV status helps you make healthy decisions to prevent getting or transmitting HIV.
Are there symptoms?
Some people have flu-like symptoms within 2 to 4 weeks after infection (called acute HIV infection). These symptoms may last for a few days or several weeks. Possible symptoms include
- Night sweats,
- Muscle aches,
- Sore throat,
- Swollen lymph nodes, and
- Mouth ulcers.
But some people may not feel sick during acute HIV infection. These symptoms don’t mean you have HIV. Other illnesses can cause these same symptoms.
See a health care provider if you have these symptoms and think you may have been exposed to HIV. Getting tested for HIV is the only way to know for sure.
This animated video explains the reasons why you should get tested for HIV.
What are the stages of HIV?
When people with HIV don’t get treatment, they typically progress through three stages. But HIV medicine can slow or prevent the progression of the disease. With the advancements in treatment, progression to Stage 3 is less common today than in the early days of HIV.
Stage 1: Acute HIV Infection
- People have a large amount of HIV in their blood. They are very contagious.
- Some people have flu-like symptoms. This is the body’s natural response to infection.
- But some people may not feel sick right away or at all.
- If you have flu-like symptoms and think you may have been exposed to HIV, seek medical care, and ask for a test to diagnose acute infection.
- Only antigen/antibody tests or nucleic acid tests (NATs) can diagnose acute infection.
Stage 2: Chronic HIV Infection
- This stage is also called asymptomatic HIV infection or clinical latency.
- HIV is still active but reproduces at very low levels.
- People may not have any symptoms or get sick during this phase.
- Without taking HIV medicine, this period may last a decade or longer, but some may progress faster.
- People can transmit HIV in this phase.
- At the end of this phase, the amount of HIV in the blood (called viral load) goes up and the CD4 cell count goes down. The person may have symptoms as the virus levels increase in the body, and the person moves into Stage 3.
- People who take HIV medicine as prescribed may never move into Stage 3.
Stage 3: Acquired Immunodeficiency Syndrome (AIDS)
- The most severe phase of HIV infection.
- People with AIDS have such badly damaged immune systems that they get an increasing number of severe illnesses, called opportunistic infections.
- People receive an AIDS diagnosis when their CD4 cell count drops below 200 cells/mm, or if they develop certain opportunistic infections.
- People with AIDS can have a high viral load and be very infectious.
- Without treatment, people with AIDS typically survive for about three years.