The bottom line

The virus cannotbe transmitted through

• Unbroken healthy skin, because cells vulnerable to HIV infection do not exist on the surface of the skin.
• Breathing in: (unlike the common cold, for instance, which can be spread through sneezing), because HIV cannot be airborne. It is not present in the tiny particles of moisture sneezed or coughed out of someone's mouth.
• A healthy, undamaged mouth, because cells vulnerable to HIV infection are not present in the mouth.
• Unbroken barriers, such as a latex condom or the female condom, because these barriers cannot be penetrated by HIV.
• Corneal transplants, because no blood vessels are present on the cornea.
• Mosquitoes, because although these insects suck blood, they do not regurgitate blood containing live HIV into the bodies of other victims.
• Sharing cutlery, plates or cups, because HIV cannot be transmitted in saliva.
• Over–broad and imprecise categories such as `sex' or `promiscuity' or `drug abuse' are not in themselves a risk.
• Social contact with people with HIV, because HIV is not transmitted by touch or through the air
• Through animal bites, because animals do not carry HIV.
• By caring for people with HIV (but remember the guidelines on universal precautions, see Infection control, below).
• By association with blood (e.g. donating blood in the UK).
• By contact with small quantities of dried blood, because HIV will not be present in sufficient quantity (all infections through blood not injected or transfused have occurred where large quantities of blood splashed onto the broken skin of other people).
• Through swimming pools, showers, washing machines, because HIV will be killed by chemicals in disinfectant and detergent, or simply just washed away.
• By mouth–to–mouth resuscitation, because HIV is not present in saliva.
• By touching objects such as telephones, because HIV is not transmitted by touch.
• By using the same lavatory as people with HIV, because even if someone had bled into the lavatory, the water would immediately dilute the virus. Nor would HIV be picked up from blood on the lavatory seat.

Rarely, the virus may be transmitted through:

• The lining of the mouth if there are cuts, sores or ulcers or bleeding gums.
• The nipples, if bitten by a child with bleeding gums while breastfeeding.
• The mucous membranes in the eye, if splashed there in large quantities.

The vast majority of possible activities in life are not a risk. Sometimes people will be anxious about routes of transmission which do present a risk from other illnesses, but not HIV. So, apart from taking reassurance that these things are not a risk, it is also important to understand how transmission does occur, and why (see The mechanisms of HIV transmission earlier in this chapter).