Typical Routes of HIV Transmission
 | Unprotected intercourse with an infected person (penile-vaginal; penile-anal; sharing sex toys) |
| Sharing needles or syringes with an infected person |
| Mother-to-child transmission, in the uterus, during childbirth, or through breast-feeding. |
HIV may also be spread through blood or blood products. This is very unlikely now because all donors are carefully screened and all donors' blood and blood products are tested before being used.
In each of these routes, certain conditions must exist in order for HIV transmission to occur. These factors, with special reference to sexual transmission, are:
| there must be a source of infection. In other words, HIV must be present in certain bodily fluids, such as blood, semen or vaginal fluids; |
| there must be an entry site into the bloodstream, usually through a break in the skin or absorption through mucosal linings. (This is why unprotected anal and vaginal sex are particularly problematic, because of frequent mucosal tears); and |
| there must be a sufficient level of the virus delivered to establish infection. Blood, semen and vaginal fluids are of concern here because of their high quantity or concentration of the virus. |
No Risk
You cannot get HIV by:
| Being bitten by a mosquito |
| Donating blood |
| Sharing food, plates , utensils |
| Sitting next to someone |
| Touching, shaking hands, hugging , dry kissing |
| Using restrooms, water fountains or telephones |
Theoretical Risk
In determining the levels of risk for the transmission of HIV, one must consider the principles of transmission and the presence and concentration of HIV in different body fluids. These are considered theoretical because the amounts, conditions and media of exchange are such that the efficiency of HIV transmission appears to be greatly diminished. Some theoretical risks are greater than others. For instance, the quantity of HIV that is carried in saliva makes this body fluid an unlikely source of infection.
Methods of Prevention
The main methods of prevention include:
| Using a latex condom during penis/anal or penis/vaginal sex (with plenty of water based lubricant during anal and vaginal sex) and during mouth/penis sex or when sharing toys. |
| Using a dental dam or condom cut open for vagina/vagina or mouth/vagina sex |
| If sharing needles, cleaning them properly with bleach. (The best protection when using needles is to use your own, clean needles) |