HIV is a virus transmitted from person to person, most commonly through sex without a condom or reuse of drug use equipment after someone else has used it. It can also be transmitted to an infant during pregnancy, labour or breastfeeding. HIV cannot be passed through casual contact like hugging, kissing, shaking hands, or spending time with someone who has HIV.

HIV transmission can be simplified to a three-part equation:

Body fluids with high amounts of HIV + particular activities + entry to bloodstream = risk of infection

1. Body fluids with high amounts of HIV

If a person is infected with HIV, these body fluids may have high amounts of the virus:

  • blood (including menstrual blood)
  • semen (cum) and precum
  • vaginal fluids
  • anal or rectal fluids
  • breast milk

2. Particular activities

Some activities may allow body fluids to move one person to another:

  • vaginal sex (penis in the vagina) without a condom
  • anal sex (penis in the bum or anus) without a condom
  • reuse of syringes
  • reuse of tattooing or piercing needles
  • sharing of sex toys between partners without properly cleaning them or using some kind of protection for each partner

3. Entry point to the bloodstream

HIV can get into the body through these entry points:

  • cells on the cervix (inside the vagina)
  • cells in the anus (inside the bum or anus)
  • cells in the urethra (the tip of the penis)
  • open cuts and wounds
  • punctures through the skin (usually via needles)