Summary
HIV infects helper T cells; untreated infection depletes them, leaving the body vulnerable to opportunistic infections.
In depth
Transmission through blood, sexual contact and mother-to-child. After acute infection and a long latent period, CD4 counts fall below 200 per microlitre, defining AIDS. Antiretroviral therapy makes HIV a manageable chronic infection; PrEP prevents infection.
HIV binds CD4 and a co-receptor (CCR5 or CXCR4). People with CCR5 delta-32 mutation resist infection. Testing includes antibody/antigen tests and viral load.
Example: PrEP reduces infection risk by over 90 percent when taken correctly.
HIV-1 attaches to CD4 and the co-receptor CCR5 or CXCR4. Some people with a CCR5 delta-32 mutation are resistant, and bone marrow transplants from donors with it have cured a handful of patients. Without treatment, the average time to AIDS is about 10 years, when opportunistic infections (Pneumocystis pneumonia, tuberculosis, toxoplasmosis) and cancers such as Kaposi sarcoma appear.
About 39 million people live with HIV, and treatment allows near-normal life expectancy. Prevention includes condoms, pre-exposure prophylaxis (PrEP), treatment as prevention, needle exchange and preventing mother-to-child transmission. There is no widely available vaccine because of the virus's diversity and its hiding in latent reservoirs.
Example: undetectable viral load means the virus cannot be passed on sexually (U=U), based on large studies.
Frequently asked questions
What is HIV and AIDS?
HIV infects helper T cells; untreated infection depletes them, leaving the body vulnerable to opportunistic infections.
Which area of biology covers HIV and AIDS, and how advanced is it?
HIV and AIDS is one of the 52 topics in Immunology & Disease. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Retroviruses, Transplant Rejection, Immunodeficiency.
Can you give an example of HIV and AIDS?
Undetectable equals untransmittable (U=U).
What should I learn before HIV and AIDS?
Work through the Beginner topics in Immunology & Disease first, such as Immune System, Viruses, Innate Immunity, then return to HIV and AIDS. Intermediate topics assume the Beginner vocabulary.
What topics are related to HIV and AIDS?
The closest topics to HIV and AIDS are Retroviruses, Transplant Rejection, Immunodeficiency, Bacterial vs Viral Infections. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand HIV and AIDS?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for HIV and AIDS. To practise the whole of Immunology & Disease, use the Immunology & Disease quiz.
How is HIV and AIDS different from Retroviruses?
HIV and AIDS: HIV infects helper T cells; untreated infection depletes them, leaving the body vulnerable to opportunistic infections. Retroviruses: RNA viruses like HIV that use reverse transcriptase to make DNA that integrates into the host genome. Read both side by side and note what each one explains.
How should I study HIV and AIDS step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Retroviruses and explain the difference aloud. Finally, take the Immunology & Disease quiz and come back to this page for any question you miss.