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HIV & AIDS Health Center

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HIV (Human Immunodeficiency Virus) Infection - What Happens

How HIV is spread

HIV is spread when blood, semen, or vaginal fluids from an infected person enter another person's body, usually through:

  • Sexual contact. The virus may enter the body through a tear in the lining of the rectum, vagina, urethra, or mouth. Most cases of HIV are spread this way.
  • Infected blood. HIV can be spread when a person:
    • Shares needles, syringes, cookers, cotton, cocaine spoons, or eyedroppers used for injecting drugs or steroids.
    • Is accidentally stuck with a needle or other sharp item that is contaminated with HIV.

HIV may be spread more easily in the early stage of infection and again later, when symptoms of HIV-related illness develop.

Recommended Related to HIV/AIDS

HIV, AIDS, and Mycobacterium Avium Complex

Mycobacterium avium complex (MAC) is a group of bacteria that are related to tuberculosis. These germs are very common in food, water, and soil. Almost everyone has them in their bodies. If you have a strong immune system, they don't cause problems. But they can cause serious illness in people with HIV (human immunodeficiency virus). With the right combination of medications, however, you can prevent or treat MAC. In some cases, you may need lifelong therapy.

Read the HIV, AIDS, and Mycobacterium Avium Complex article > >

A woman who is infected with HIV can spread the virus to her baby during pregnancy, delivery, or breast-feeding.

How HIV is not spread

The virus doesn't survive well outside the body. So HIV cannot be spread through casual contact with an infected person, such as by sharing drinking glasses, by casual kissing, or by coming into contact with the person's sweat or urine.

It is now extremely rare in the United States for HIV to be transmitted by blood transfusions or organ transplants.

The window period

After you've been infected, it can take 2 weeks to 6 months for your body to start making HIV antibodies.

This means that during this time you could have a negative HIV test, even though you have been infected and can spread the virus to others.

This is commonly called the "window period," or seroconversion period.

Stages of HIV

Most people go through the following stages after being infected with HIV:

Initial stage (stage 1)

The first stage of HIV infection is defined by the U.S. Centers for Disease Control and Prevention (CDC) as a CD4+ cell count of at least 500 cells per microliter or a percentage of CD4+ cells at least 29% of all lymphocytes. People in this stage don't have any symptoms.4

Chronic stage (stage 2)

The second stage of HIV infection is defined by the CDC as a CD4+ cell count of 200 to 499 or a percentage of CD4+ cells of 14% to 28%.4 It may take years for HIV symptoms to develop during this stage. But even though no symptoms are present, the virus is making copies of itself (multiplying) in the body during this time.

HIV multiplies so quickly that the immune system can't destroy the virus. After years of fighting HIV, the immune system starts to weaken.

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