Quick Answer

AIDS is the most advanced stage of HIV infection, marked by severe immune damage and certain opportunistic infections or cancers. HIV is a retrovirus that attacks immune cells; with modern treatment, viral load can become undetectable, stopping progression to AIDS and preventing transmission (U=U).

  • HIV is a retrovirus that targets CD4 immune cells.
  • AIDS develops when CD4 count drops below 200 cells/mm³.
  • Modern antiretroviral therapy can make HIV undetectable.
  • Undetectable equals untransmittable (U=U) per CDC guidance.
  • People with HIV can live long, healthy lives with treatment.
  • AIDS is not a separate illness but a stage of HIV.

Context Most Pages Skip

HIV and AIDS are often confused, but understanding the difference is key to prevention and treatment. HIV (human immunodeficiency virus) is a retrovirus that gradually destroys CD4 cells, which are vital for immune function. Without treatment, the immune system weakens, leading to AIDS (acquired immunodeficiency syndrome). However, modern antiretroviral therapy (ART) can suppress HIV to undetectable levels, preserving health and preventing transmission. This guide explains the mechanism, course, and complications of HIV and AIDS.

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⚕️ This page is educational and does not replace advice from a licensed clinician. If you may have been exposed to an STI, get tested — most infections are manageable, and many are fully curable.

Sources & Further Reading

Figures reflect CDC surveillance and WHO estimates; they are population statistics, not personal risk predictions.