Quick Answer

AIDS - acquired immunodeficiency syndrome - is the most advanced stage of HIV infection, not a separate virus or a synonym for HIV. It is defined by severe immune damage, such as a CD4 count below 200 cells per microliter or the appearance of specific opportunistic infections. Modern HIV treatment usually prevents AIDS from ever developing.

  • HIV is a retrovirus that inserts its genetic code into immune cells.
  • AIDS is a stage of HIV infection classified by specific immune and clinical criteria.
  • CDC labels AIDS as stage 3 HIV, based on CD4 count or opportunistic infections.
  • Not everyone with HIV develops AIDS, especially with early treatment.
  • Effective treatment can push viral load to undetectable, which means untransmittable.
  • HIV and AIDS are not interchangeable terms in medical classification.

Context Most Pages Skip

HIV is a retrovirus, meaning it copies its genetic material into the DNA of the cells it infects - chiefly CD4 T cells, the coordinators of the immune response. Because those cells are lost or disabled over time, the body becomes progressively less able to fight infections it would normally shrug off. AIDS is the name given to the point when that damage crosses a defined threshold. The distinction matters because it separates a manageable chronic infection from an advanced condition, and because the vocabulary people use shapes how they think about testing, treatment, and risk.

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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.