Quick Answer

AIDS forms when untreated HIV infection destroys enough CD4 immune cells that the body can no longer fight off infections. HIV is the virus; AIDS is the advanced stage of the disease. Modern antiretroviral therapy can stop this progression and keep viral load undetectable, which also prevents transmission.

  • HIV is a retrovirus that attacks CD4 cells, weakening the immune system.
  • Without treatment, HIV can progress to AIDS over several years.
  • AIDS is diagnosed by a CD4 count below 200 cells/mm³ or certain infections.
  • Antiretroviral therapy can suppress HIV to undetectable levels.
  • Undetectable viral load means no risk of sexual transmission (U=U).
  • Early testing and treatment prevent progression to AIDS.

Context Most Pages Skip

HIV (human immunodeficiency virus) is a retrovirus that targets and destroys CD4 cells, which are essential for a healthy immune response. As the virus replicates, it gradually depletes these cells, leaving the body vulnerable. AIDS (acquired immunodeficiency syndrome) is the most severe phase of HIV infection, defined by a critically low CD4 count or the occurrence of specific opportunistic infections. Understanding the difference between HIV and AIDS is key: HIV is the cause, AIDS is the consequence of untreated infection. Modern treatment can halt this process entirely.

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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.