Anonymous on October 20, 2011

What are HIV and AIDS?

I hear a lot about them, but I’m confused about the difference between HIV and AIDS. Can you help? 

answered by Lisa Oldson, MD on October 20, 2011

That’s a great question. We often hear about HIV and AIDS in the same breath, but you’re right: they’re different. 

What is HIV? The human immunodeficiency virus (HIV) attacks the immune system. Over time, the virus makes it harder for the body to fight off infections. 

How do you get HIV? HIV is transmitted through bodily fluids like semen, blood, vaginal fluid and breast milk. One of the most common ways that people get HIV is through unprotected sex with an infected person. However, some people get HIV from intravenous drug use, blood exposure (e.g., blood transfusions, in rare cases) or it’s possible for children of infected women to get it from breast milk. 

Once in the body, HIV attacks the immune system by damaging T-cells. T-cells are known as the “generals” of the immune system because they tell the immune cells to attack an “intruder” (like a virus or bacteria that enters the body). 

Because HIV damages T-cells, the immune system will begin to weaken without treatment. When a person’s T-cell count gets low, doctors will generally say that person has acquired immune deficiency syndrome (AIDS), which is an often life-threatening condition. 

In other words, HIV is the virus that can cause AIDS...and AIDS is a syndrome that describes an advanced or serious stage of an HIV infection. 

But not everyone who has HIV gets AIDS. Especially these days, if a person with HIV is diagnosed early, there are increasingly effective medications that can help a person with HIV live a normal, healthy life for as long as possible. 

How can you find out if you have HIV? Getting a blood test is the only way to know if you have HIV. So, if you’re sexually active ⎼ especially if you’ve ever had unprotected sex with someone whose STD status you don’t know ⎼ it’s a smart idea to get tested for HIV and other common sexually transmitted diseases (STDs) on a regular basis. 

Have more questions? You can learn more about HIV and AIDS in our Expert Guide to HIV. 

Related info: 

Lisa Oldson, MD

Dr. Oldson is Medical Director of the Analyte Physicians Group. She is on staff at Northwestern Memorial Hospital, as well as Clinical Instructor at the Feinberg School of Medicine, Northwestern University. Her areas of expertise include STDs (with a particular clinical emphasis on herpes), women's health, preventive medicine, diabetes, obesity and weight management, and mood and anxiety disorders. Dr. Oldson was educated at Rush Medical College and completed her residency at Rush-Presbyterian-St. Luke's Medical Center in Chicago, IL.

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