What is HIV?

HIV stands for Human Immunodeficiency Virus. It is a virus that attacks the body's immune system, specifically the CD4 cells (T cells), which are crucial for fighting off infections. If left untreated, HIV reduces the number of CD4 cells in the body, making a person more and more vulnerable to other infections and diseases.

Unlike some other viruses, the human body can't get rid of HIV completely, even with treatment. So once you have HIV, you have it for life. However, 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.

Illustration of a virus under a microscope.

The Difference Between HIV and AIDS

It's important to know that HIV and AIDS are not the same thing.

HIV: The Virus

HIV is the virus that is transmitted from person to person. It attacks and weakens the immune system. A person can have HIV for many years without developing AIDS, especially with effective treatment.

AIDS: The Condition

AIDS (Acquired Immunodeficiency Syndrome) is the most advanced stage of HIV infection. A person is diagnosed with AIDS when their immune system is severely damaged (a very low number of CD4 cells) or they develop certain opportunistic infections.

How HIV is Transmitted

HIV is transmitted through specific bodily fluids from an HIV-positive person.

HIV CAN be transmitted through:

Blood
Semen and pre-seminal fluid
Rectal fluids
Vaginal fluids
Breast milk

For transmission to occur, these fluids must come into contact with a mucous membrane (like those found in the rectum, vagina, mouth, or tip of the penis), damaged tissue, or be directly injected into the bloodstream (from a needle or syringe).

HIV is NOT transmitted by:

Air or water
Mosquitoes, ticks or other insects
Saliva, tears, or sweat (that is not mixed with blood)
Hugging, shaking hands, sharing toilets, or sharing dishes

The Stages of HIV Infection

Within 2 to 4 weeks after infection with HIV, about two-thirds of people will have a flu-like illness. This is the body’s natural response to infection. Flu-like symptoms can include fever, chills, rash, night sweats, muscle aches, sore throat, and fatigue. During this stage, there is a large amount of virus in the blood, and people are very contagious. But people with acute infection are often unaware that they have HIV because they may not feel sick right away or at all. To know for sure, you need to get tested.

This period is sometimes called asymptomatic HIV infection or chronic HIV infection. During this phase, HIV is still active but reproduces at very low levels. People may not have any symptoms or get sick during this time. For people who aren’t taking medicine to treat HIV, this period can last a decade or longer, but some may progress through this phase faster. People who are taking medicine to treat HIV (antiretroviral therapy or ART) may be in this stage for several decades. It’s important to remember that people can still transmit HIV to others during this phase.

AIDS is 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. Without treatment, people with AIDS typically survive about 3 years. Common symptoms of AIDS include chills, fever, sweats, swollen lymph glands, weakness, and weight loss. People are diagnosed with AIDS 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.

The only way to know your HIV status is to get tested.

Learn About Testing Options