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It’s important to know how HIV can get into your body and what happens once it’s there. Then you’ll be better prepared to protect yourself or others against this virus. A person with HIV can look and feel perfectly healthy. But that person can give HIV to others as soon as he or she is infected with the virus.

Having unsafe or unprotected sex or sharing needles puts you at risk for HIV. Talk with your healthcare provider about ways to protect yourself or a loved one from getting HIV.

How HIV infection progresses

After HIV enters the body, it attacks the immune system in the stages below. A person with HIV can infect others once the virus gets into the blood.

  • HIV with no symptoms. A person with HIV may have no symptoms for years. The only sign of infection may be a positive blood test for HIV 2 weeks to 3 months or later after HIV enters the body.
  • HIV with symptoms. Some people develop an illness similar to mono (mononucleosis) 2 to 4 weeks after the virus enters the body. This is called acute retroviral syndrome. Symptoms may include swollen lymph glands, chills, fever, night sweats, weakness, weight loss, skin rashes, mouth ulcers, or sore throat. Symptoms may be mild or the person can feel quite sick. Even without treatment the symptoms almost always go away in a few days or up to 2 to 3 weeks. Then the person has no symptoms, often for years. But over time the immune system starts to get weaker and symptoms start appearing. People at this stage may have a yeast infection in the mouth (oral thrush), shingles, skin problems, pneumonia, diarrhea that keeps coming back, or weight loss.
  • AIDS. AIDS is the most advanced stage of HIV infection, when the immune system is severely weakened. Certain rare diseases and cancers that normally would not occur, now can occur because the body can no longer fight them well enough. It is often these diseases that cause death in people with AIDS. HIV may also directly attack the brain and nervous system. This causes seizures and loss of memory and body movement. It also affects many other parts of the body. This leads to problems such as anemia, low white blood cell count, diarrhea, belly pain, skin problems, and many others.

How HIV enters the body

HIV is carried in semen, vaginal fluid, blood, and breastmilk.

During sex, HIV can enter the body. It gets in through the fragile tissue and linings, sores, or cuts in or around the vagina, penis, anus, and mouth.

During drug use, tattooing, or body piercing, the virus can enter the blood through an infected needle.

A mother who has HIV can infect her child during pregnancy, childbirth, and breastfeeding.