What are the routes of infection?

Common routes include:

• Contact with the mucous membranes of genital or anal tissue. A mucous membrane is a type of tissue that is a less effective barrier than skin. The inner foreskin is also a mucous membrane.
• Ulcers, sores, scratches, cuts or microabrasions (microscopic cuts) on genital tissue (to the vagina, penis or anal lining).
• Any direct route into the bloodstream including cuts in your mouth. Sharing needles and injecting equipment has one of the highest risks of transmitting HIV. This is because there is a direct blood-to-blood route.

The section on skin, mucous membranes and HIV transmission show the different cell structures for skin and mucous membranes.

They show why some risks are higher than others and why anal sex has an especially high risk.

They show why uncircumcised men have a higher risk for some types of sex compared to circumcised men.

These drawings show the different biology for penile, vaginal and anal sex. They show why some risks are higher than others and why anal sex has an especially high risk.

They show why an uncircumcised man has a higher risk for some activities compared to a circumcised man.

Last updated: 1 June 2021.