How HIV is transmitted from one person to another is still misunderstood by many people. Knowing the basics helps you avoid getting the virus if you are HIV-negative, and avoid passing it on if you are HIV-positive.

HIV is spread through the following body fluids:

• Blood (including menstrual blood)
• Semen and other male sexual fluids ("pre-cum")
• Vaginal fluids
• Breast milk

HIV is not spread through these body fluids:

• Sweat
• Tears
• Saliva (spit)

The spread of HIV can be prevented! There are ways to avoid, or at least reduce, contact with bodily fluids that spread HIV (blood, sexual fluids, and breast milk). This info sheet will explain how.

In the past, HIV was spread in blood products, such as whole blood or the "factor" used by hemophiliacs. Many people were infected this way. The blood supply is now much more strictly tested and controlled. The odds of being infected from receiving blood or blood factor in the U.S. are extremely low.

You cannot get HIV from donating blood – a new clean needle is used for each donation.

Some people, primarily healthcare workers, are occasionally infected through needle sticks with infected blood, or through other medical accidents. This is a very tiny percentage of overall infections.

Today, the most common ways HIV is passed from one person to another are:

• Re-using and sharing needles
• Unprotected/unsafe sex (no condoms or other barrier devices)
• Mother-to-child (during pregnancy, birth, or breast-feeding)

Many HIV infections occur when people share needles to inject heroin, methamphetamine, or other drugs. This risk can be greatly reduced by cleaning needles with a bleach solution before re-using them. The risk can be eliminated by using fresh needles each time. Many cities now offer free needle exchange programs.

Tattoos or body piercings should always be done by a licensed professional whose equipment is autoclaved, not just "sterilized" with alcohol.

Every sexual act (oral, anal, or vaginal) that involves sexual fluids of some kind has at least some risk. Barriers, such as condoms (male and female), dental dams, and even latex gloves help reduce risk substantially

Unsafe sex (sex without condoms or barriers) puts you and your partner at risk for HIV or other sexually transmitted diseases (STDs).

Safer sex (sex using condoms or other barriers correctly and consistently) protects you and your partner.

Which common sexual activities are most likely to cause HIV transmission when safer sex isn't used? (Listed from most to least risky.)

1. Receptive anal sex ("bottoming") remains the most risky activity, due to the likelihood of direct semen-blood contact. But penetrative anal sex ("topping") with someone can result in HIV transmission, too.
2. Vaginal intercourse puts both partners at risk, but HIV is transmitted from men to women much more easily than from women to men.
3. Oral sex can be risky for the person performing it, particularly if he or she swallows semen, vaginal fluids, or menstrual fluids.
4. Sharing sex toys without sterilizing them can be dangerous.
5. Rimming (licking the anus) is very unlikely to result in HIV infection.
6. Mutual masturbation (hand jobs) and fisting (using a hand to penetrate the anus or vagina) are relatively risk-free, as long as your hand has no open cuts or sores.

Sexual assault or rape can result in infection if the attacker is HIV-positive. The risk increases when rape involves anal penetration, force, and/or multiple attackers. Some forced sexual acts involving wounds can place a victim at very high risk.

In major cities, PEP (post-exposure prophylaxis) is often offered to victims of sexual assault or rape. This month-long treatment reduces the likelihood of HIV infection substantially. It is currently only used on a regular basis for victims of sexual assault and for healthcare workers who have been exposed to HIV on the job. PEP must be started as quickly as possible, always within 72 hours of the exposure.

HIV-positive mothers can pass the virus to their babies while pregnant, during birth, or by breastfeeding. New medical techniques have almost eliminated the risk of a baby getting HIV from its mother when precautions are taken. HIV-positive mothers should not breastfeed their babies.

There are a few isolated cases of people becoming infected from using a razor that had just been used by an HIV-positive man, or from using a toothbrush immediately after the toothbrush was used by someone who was HIV-positive, or in other unexpected ways. To be safe, always avoid direct contact with blood and sexual fluids in any context.

Don't worry too much about freak cases. For instance, there is a documented case of transmission from deep or "French" kissing – in two people who had terrible dental problems. However, the odds of getting HIV from kissing, even when one person is HIV-positive, are less than the odds of being struck by lightning.

HIV cannot be transmitted except when certain bodily fluids are exchanged. You can greatly reduce the risk of transmission by:

• Avoiding contact with sexual fluids by always practicing safer sex
• Abstaining from sex unless you and your partner are both HIV-negative and in a long-term, monogamous relationship
• Not using injection drugs, or if you do, always using new or clean needles
• Finding our your HIV status if you are planning to get pregnant and working with a knowledgeable doctor and obstetrician if you are HIV-positive

If you protect yourself in these ways, you do not need to be afraid of getting or passing HIV by casual contact. Remember, HIV is not transmitted by:

• Hugs
• Dancing
• Sharing food or drinks
• Using a shower, bath, or bed used by an HIV-positive person
• Kissing (between people with no significant dental problems)
• Sharing exercise equipment