Quick Answer

AIDS itself is not infectious; it is the late stage of HIV infection, when the immune system is severely damaged, and it cannot be passed from person to person. HIV, the virus that causes AIDS, is infectious and spreads through specific body fluids - mainly blood, semen, vaginal fluids, and breast milk. With effective HIV treatment, viral load can become undetectable, and per CDC, that means effectively no sexual transmission risk.

  • AIDS is a stage of HIV infection, not a separate contagious disease.
  • HIV is the infectious agent; AIDS is the clinical syndrome it can cause.
  • HIV spreads through blood, semen, vaginal fluids, and breast milk.
  • It does not spread through hugging, sharing food, mosquitoes, or casual saliva contact.
  • HIV is a chronic infectious disease that can be managed with lifelong treatment.
  • Per CDC, an undetectable viral load means effectively no sexual transmission risk to partners.

Context Most Pages Skip

HIV is a retrovirus, meaning it inserts its genetic material into the DNA of immune cells - mainly CD4 T cells - and uses them to make copies of itself. Over years without treatment, this process depletes those cells and weakens the immune system. AIDS is not a virus but a surveillance definition for the most advanced stage of that damage, marked per CDC by a very low CD4 count or by specific opportunistic infections. This distinction matters because HIV is the transmissible infection, while AIDS is the treatable but late-stage consequence. Modern antiretroviral therapy can suppress HIV so the immune system recovers and the virus becomes undetectable.

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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.