What Is HIV (and How Is It Different Than AIDS)?

Here's how HIV and AIDS affect your immune system.

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New research for HIV, or human immunodeficiency virus, has greatly advanced HIV treatment and prevention efforts. Although there is no cure for HIV, patients who stick with their medication are living longer, stronger, and healthier lives.

HIV is a kind of virus that attacks the CD4 T cells in the immune system. This is the part of your body that protects you against infections. Upon transmission, the HIV virus multiplies rapidly and creates several million copies within the first couple of weeks, according to hematologist Jeffrey Laurence, MD, of Weill Cornell Medicine in New York City. Dr. Laurence is also is the senior scientific consultant for programs at amfAR, the Foundation for AIDS Research.

How HIV Progresses

In early stages, HIV presents itself as what many describe as the “worst flu ever.” As the body tries to fight back against the infection, someone with HIV may experience severe flu-like symptoms. Additionally, they may have skin lesions, diarrhea, headaches, and high fever.

The body adapts to this, however, and HIV shifts to a latent period, which may last several years. If untreated, the virus will continue to destroy T cells. When this occurs, HIV patients will become more vulnerable to cancers, viral hepatitis, tuberculosis, and other infections.

Doctors can track the progression of a patient’s HIV using the T cell count. Once someone’s T cell count drops below 200, the patient is diagnosed with AIDS, or Acquired Immune Deficiency Syndrome. AIDS is the last stage of HIV infection, when the immune system is at its weakest.

HIV Transmission

Transmission of HIV occurs when bodily fluids from an infected person enter another person’s body. This can occur in one of four ways: sexual transmission (including vaginal, anal, or oral), sharing needles, direct contact with contaminated blood, or transmission between a between mother and fetus. Contrary to popular belief, HIV is not transmitted through air, water, hugging, saliva, sweat, tears, mosquitos, or sharing food or drinks. (Learn more myths about HIV here.)

It is important to remember that not all people with HIV show symptoms, so doctors recommend you consistently use a condom with sexual partners when you don’t know their HIV status.

What’s important to know, says Dr. Laurence, is that “HIV is no longer a death sentence.” Modern treatments for HIV can be as simple as one pill a day. Thanks to these new treatments, doctors now see no difference in the lifespan of someone infected with HIV and someone who isn’t. The key is making sure patients adhere to their HIV drug regimen and get regular medical care.