HIV
Meaning of HIV: A virus that disables the very cells sent to fight it, so the damage appears as other infections rather than its own illness.
Definition of HIV
HIV stands for human immunodeficiency virus, a virus that infects and destroys CD4 cells, a type of white blood cell that coordinates the body's defenses. As those cells are lost, the immune system weakens and infections and cancers it would normally control begin to take hold. The infection persists for life once established.
What does the virus do to the immune system?
HIV targets the cell that organizes the response against it. CD4 cells direct other parts of the immune system, so their steady loss removes the coordination rather than one defense. The virus also writes a copy of itself into the DNA of infected cells, where it can sit silently in a reservoir that no current treatment reaches, which is why the infection persists even when nothing is detectable in the blood. Without treatment the CD4 count falls over years while the amount of virus rises, and infections that a working immune system handles without difficulty become serious.
How is it transmitted, and how is it not?
| Transmitted by | Not transmitted by |
|---|---|
| Blood, semen, vaginal and rectal fluids, breast milk | Saliva, tears, sweat, urine |
| Unprotected sex with a person whose virus is not suppressed | Hugging, kissing, sharing dishes, toilet seats |
| Shared needles or injecting equipment | Coughs, sneezes, mosquitoes |
| Pregnancy, birth or breastfeeding without treatment | Donating blood in a screened system |
The misconceptions in the right-hand column persist despite long-standing evidence against them. Treatment has also changed transmission itself: a person taking effective antiviral therapy who maintains an undetectable amount of virus in the blood does not pass HIV on through sex, a finding established across large studies.
How does HIV relate to AIDS?
They are not the same. HIV names the virus and the infection it causes; acquired immunodeficiency syndrome names the advanced stage reached when immune damage has progressed far enough, marked either by a CD4 count below a defined level or by the appearance of one of a listed set of illnesses. Combination antiretroviral treatment suppresses the virus so effectively that this stage can be prevented or reversed, so the infection is now managed as a long-term condition rather than being expected to progress. Testing detects antibodies, viral proteins or the virus itself, and the modern combined tests turn positive within weeks of infection.
Also known as
Used in a sentence
The patient was started on antiviral treatment following a new diagnosis of HIV.
Good to know
HIV infection and AIDS are not interchangeable terms, since AIDS refers to the advanced stage of untreated or inadequately treated infection defined by severe immune damage or specific illnesses.