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Human Immunodeficiency Virus (HIV) Infection and AIDS

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What is the human immunodeficiency virus (HIV)?

       The human immunodeficiency virus (HIV) is a type of virus called a retrovirus. It causes AIDS (acquired immunodeficiency syndrome), which is life-threatening.

       HIV is called an immunodeficiency virus because it weakens (causes deficiency) of your immune system. Your immune system helps defend you against infection and cancer.

HIV infection weakens your immune system because it kills certain types of white blood cells called CD4 lymphocytes. Without enough CD4 lymphocytes, you're more likely to get certain infections and cancers.

  • HIV infection weakens your body's defenses against certain infections and cancers

  • There's no cure for HIV, but HIV medicines make a big difference in slowing down the virus

  • Without treatment, HIV causes AIDS

  • Starting HIV medicines as soon as you can may help you avoid AIDS-related problems

  • People don’t die from HIV itself, but from complications of the infections and cancers they get

  • Practicing safe sex, not sharing needles, and not getting other people's blood on you help prevent HIV infection

What is acquired immunodeficiency syndrome (AIDS)?

       AIDS is acquired immunodeficiency syndrome. Not everyone with HIV infection has AIDS. You have AIDS when you have HIV infection along with either:

  • A very low number of CD4 lymphocytes

  • Certain infections and cancers

There are many infections and cancers that define AIDS. Some common ones include:

  • Fungal infections of your esophagus (the "food pipe" that connects your throat and your stomach), brain, or lungs

  • Tuberculosis

  • Kaposi sarcoma, a cancer that causes painless red or purple blotches on your skin or inside your mouth

  • Non-Hodgkin lymphoma and certain other cancers

  • Certain infections that a healthy immune system can fight off but a weak one can't, such as pneumocystis pneumonia, toxoplasmosis, and cytomegalovirus

       People with AIDS often have severe weight loss—this is called "AIDS wasting."

What causes HIV infection?

       When the HIV virus takes over a CD4 lymphocyte, it makes many copies of itself before killing the CD4 cell and releasing the virus copies. Those copies then take over other CD4 lymphocytes, which make even more copies. This cycle continues until there are billions of HIV in your body.

       You can be infected with HIV from contact with the body fluids of an infected person, especially:

  • Blood

  • Semen

  • Vaginal fluids

  • Breast milk

       It’s rare to get infected from someone's tears, urine, or saliva. These fluids carry the virus but in smaller amounts.

  • You can get HIV by having unprotected sex with an infected person

  • You can get HIV by sharing needles with an infected person

  • Children can get HIV from infected mothers during pregnancy, childbirth, and breastfeeding

  • But you can’t get HIV by touching, holding, or being near someone with HIV

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Source: www.merckmanuals.com

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