Saturday, 13 October 2012

HIV transmission, How HIV spread

HIV Transmission

How HIV Spreads
Many people still do not understand how HIV is passed, or transmitted, from one person to another. Knowing the basics helps you avoid getting the virus if you are HIV-negative, and avoid giving it to someone else if you are living with HIV (HIV+).

HIV is spread through contact with the following body fluids:
  • Blood (including menstrual blood)
  • Semen (“cum”) and other male sexual fluids ("pre-cum")
  • Vaginal fluids
  • Breast milk
HIV is also spread through contact with these body fluids; however, usually only health care workers come into contact with these fluids:
  • Fluid around the brain and spinal cord (cerebrospinal fluid)
  • Fluid around the joints (synovial fluid)
  • Fluid around a developing fetus (amniotic fluid)
HIV is not spread through contact with these body fluids:
  • Sweat
  • Tears
  • Saliva (spit)
  • Feces (poop)
  • Urine (pee)
The spread of HIV can be prevented! There are ways to avoid, or at least reduce, contact with body fluids that spread HIV. This info sheet explains how.

Methods of Transmission
Today, the most common ways HIV is passed from one person to another are:
  • Re-using and sharing needles for injecting drugs (including steroids or hormones)
  • Unprotected/unsafe sex (no condoms or other barriers)
  • Mother-to-child (during pregnancy, birth, or breast-feeding)

Re-using and Sharing Needles for Injecting Drugs
  • Injecting Drugs (including steroids or hormones): Many HIV infections occur when people share the equipment used to inject heroin, methamphetamines, steroids, hormones, or other drugs. Re-using syringes, needles, water, spoons, “cookers,” or “cottons” can spread HIV. Be sure to use syringes and needles only from reliable sources, such as needle exchange programs or pharmacies. Many cities offer free needle and syringe exchange programs. For more information, see our info sheet on Cleaning Works.
  • Tattoos or Body Piercings: Tattoos or body piercings should always be done by a licensed professional whose equipment is sterile. The Centers for Disease Control and Prevention (CDC) recommends that instruments be used only once and then thrown away. Reusable instruments must be sterilized between uses. Using alcohol to clean instruments is not sufficient. Proper sterilization involves having instruments steam sterilized, or autoclaved.

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

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

Safer sex (sex using condoms or other barriers consistently and correctly) is the most effective way to protect you and your partner.

Which common sexual activities are most likely to cause HIV transmission when safer sex is not used? Listed from most to least risky:
  1. Receptive anal sex ("bottoming"): Taking a penis through one’s anus and into one’s rectum remains the most risky activity. This is due to the likelihood of small tears in the rectum that allow semen (“cum”) to have direct contact with the bloodstream.
  2. Receptive vaginal intercourse:This refers to taking a penis into one’s vagina. HIV is transmitted from men to women much more easily than from women to men.
  3. Insertive anal sex (“topping”): Putting one’s penis into someone else’s anus and rectum can expose you to HIV.
  4. Insertive vaginal intercourse:Putting one’s penis into a vagina, especially when the woman is menstruating, can expose you to HIV.
  5. Giving oral sex:Using one’s mouth to lick, suck, or bite another person’s genitals (penis, vagina, or anus) can expose you to HIV. Swallowing semen (“cum”), licking menstrual blood, and having bad oral hygiene (mouth sores, bleeding gums) will increase your risk of getting HIV.
  6. Receiving oral sex: Having your genitals licked, sucked, or bitten is less risky than giving oral sex. However, you can get HIV from your partner, especially if your partner has bad oral hygiene.
  7. Sharing sex toys without sterilizing them or using a new condom:This can allow HIV to be transmitted from the first partner to the next one who uses the toy.
  8. Mutual masturbation (hand jobs) and fisting (using a hand to penetrate the anus or vagina):These are relatively low risk, as long as your hand has no open cuts or sores.
Sexual assault or rape can result in infection if the attacker is HIV+. 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.

Survivors of sexual assault or rape who do not already have HIV should be routinely offered PEP (post-exposure prophylaxis; also called non-occupational PEP, or nPEP) in emergency rooms. This 28-day treatment with HIV drugs greatly reduces the chances of becoming infected with HIV. PEP must be started within the first 72 hours of exposure to be effective. The earlier treatment is started, the more effective it will be. If PEP is not offered in the emergency room or clinic after a rape or sexual assault, do not be afraid to ask for it. The CDC issued recommendations for PEP following non-occupational exposures like sexual assault and rape in 2005.

Mother-to-Child Transmission
HIV+ mothers can pass the virus to their babies while pregnant, during birth, or by breastfeeding. Medical care and HIV drugs given during pregnancy can almost eliminate the risk of a baby getting HIV from its mother. In high-income countries like the US, it is recommended that HIV+ mothers not breastfeed their babies. For more information, see our Pregnancy and HIV info sheet.

Other Types of Transmission
In the past, HIV was spread by transfusion with 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 US are very low.

It is also possible to get HIV from skin grafts or transplant organs taken from HIV+ people. Again, the risk is considered very low, as these ‘body products’ are required to be strictly tested in the same way as blood products. Semen donations collected by sperm banks for artificial insemination are also considered ‘body products’ and strictly tested. Private semen samples that are not processed by sperm banks or similar organizations are not subject to the same testing. It is important for anyone receiving a private donor’s sperm for artificial insemination to have the donor tested for HIV.

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

Some people, mostly health care workers, are infected through needle sticks with infected blood, or through other medical accidents. This is a very small percentage of overall infections. When exposed to fluid or body products that may be infected while on the job, health care workers are offered occupational post-exposure prophylaxis (oPEP).

Rare Types of Transmission
There are a few isolated cases of people becoming infected from using a razor that had just been used by an HIV+ person, or from using a toothbrush immediately after the toothbrush was used by someone who was HIV+, or in other unexpected ways. One case of transmission occurred when two people, both of whom had terrible dental problems, engaged in deep or "French" kissing. However, the odds of getting HIV from kissing, even when one person is HIV+, are less than the odds of being struck by lightning. To be safe, always avoid direct contact with blood and sexual fluids.

Avoiding Transmission
HIV cannot be transmitted except when certain body fluids are exchanged. You can greatly reduce the risk of transmission by:
  • Knowing your HIV status so you can take steps to avoid spreading HIV if you are HIV+
  • Practicing safer sex
  • Having unprotected sex only if you and your partner are both HIV-negative and in a monogamous relationship
  • Abstaining from sex
  • Not injecting drugs
  • Using new or clean needles for any injections
  • Staying on your HIV drug regimen if you are HIV+. This will keep your viral load as low as possible. Keeping your viral load low will reduce the risk of your passing HIV to others (sexual partners, mother-to-child).
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+ person
  • Kissing (between people with no significant dental problems)
  • Sharing exercise equipment
  • Bug bites

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