What Are HIV and AIDS?
HIV is a virus that attacks the immune system. Without treatment, it can lead to AIDS. Learn the facts, how it spreads, and how treatment can help you live a long, healthy life.
KEY POINTS
- •HIV is a virus that attacks the body's immune system, making it harder to fight infections and disease.
- •If left untreated, HIV can lead to AIDS — the late stage of HIV infection.
- •While there is no cure, effective treatment allows people with HIV to live long, healthy lives.
- •The only way to know if you have HIV is to get tested.
- •HIV treatment can reduce the viral load to undetectable levels, preventing transmission to others (U=U).
What is HIV?
HIV stands for Human Immunodeficiency Virus. It is a virus that attacks the immune system — specifically the CD4 cells (also called T cells) that help the immune system fight off infections and disease. Over time, HIV can destroy so many of these cells that the body can't fight off infections and diseases anymore.
Without treatment, HIV can lead to AIDS (Acquired Immunodeficiency Syndrome), which is the most advanced stage of HIV infection. However, with modern antiretroviral therapy (ART), people with HIV can live long, healthy lives and prevent transmission to others.
HIV vs. AIDS: What's the Difference?
HIV and AIDS are not the same thing. HIV is the virus; AIDS is the disease that can develop if HIV is left untreated.
| Aspect | HIV | AIDS |
|---|---|---|
| Definition | A virus that attacks the immune system | The advanced stage of HIV infection |
| CD4 Count | Usually above 200 cells/mm³ | Below 200 cells/mm³ or AIDS-defining illness present |
| Symptoms | May have no symptoms initially | Severe infections and opportunistic diseases |
| Transmission | Can be transmitted to others | Can be transmitted to others |
| Treatment | Antiretroviral therapy (ART) effective | ART can restore immune function |
How HIV Works in the Body
HIV works by attaching to CD4 cells and integrating its genetic material into the cell. Once inside, the virus uses the cell's machinery to make copies of itself. These new virus particles then leave the cell and infect other CD4 cells, continuing the cycle.
As more CD4 cells are destroyed, the immune system becomes weaker. This is measured by the CD4 count — the number of CD4 cells in a cubic millimeter of blood. A normal CD4 count is 500–1,500 cells/mm³. When the count drops below 200 cells/mm³, the person is at risk for serious infections.
Testing and Diagnosis
The only way to know if you have HIV is to get tested. HIV tests detect antibodies or antigens (proteins) produced in response to HIV infection. There are several types of tests available:
- Antibody tests:Detect antibodies produced by the immune system in response to HIV. These are the most common tests.
- Antigen/antibody tests:Can detect both HIV antibodies and antigens (proteins from the virus itself), allowing earlier detection.
- Nucleic acid tests (NAT):Detect HIV RNA directly and can identify infection as early as 10 days after exposure.
- Rapid tests:Provide results in 20 minutes and can be done at home or in a clinic.
HIV Treatment
Modern HIV treatment uses antiretroviral therapy (ART) — a combination of medications that suppress HIV replication. When taken consistently, ART can reduce the viral load to undetectable levels, meaning the amount of HIV in the blood is so low it cannot be detected by standard tests.
An undetectable viral load has two major benefits:
- Health benefit: Allows the immune system to recover and prevents progression to AIDS.
- Prevention benefit (U=U): A person with an undetectable viral load cannot transmit HIV through sex to their partners.
Learn More
For more information about HIV, explore our comprehensive resources: