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A quick breakdown on how HIV can be transmitted

This topic will be split into 3 parts; Definite ways of HIV transmission, theoretical ways of transmission, and no way of transmission.

Bear in mind that in order for HIV to be transmitted fluid from a positive person has to come into contact with the negative person. Semen and blood hold high loads of the virus but saliva and vaginal fluid hold very little.

 

HIV-modes-of-transmission

 

Definite ways of HIV transmission (risk will be listed as risk per 10000 – so 1/10000 means that for every 10000 people who engage in that activity, 1 person will become infected.

  • Blood transfusion – 9250/10000 (this is only with HIV infected blood which is very rare nowadays as every donor blood sample is screened before use).
  • Needle sharing in intravenous drug use – 63/10000.
  • Needlestick injury – 23/10000.
  • Receptive anal sexual intercourse – 138/10000.
  • Insertive anal sexual intercourse – 11/10000
  • Receptive penile-vaginal sexual intercourse – 8/10000
  • Insertive penile-vaginal sexual intercourse – 4/10000
  • Receptive and insertive oral sexual intercourse – low (too low for accurate numbers).

 

HIV_transmission-risk

 

Estimated risk per exposure to HIV transmission: assume that the ‘source partner’ is always HIV-positive. For a partner of unknown status, the risk is affected by the prevalence of HIV in the relevant community – i.e., the chance that the partner does in fact have HIV. Unless otherwise stated, the sexual acts are always without a condom.

 

Theoretical ways of HIV transmission:

  • Blood contact onto an open wound – possible but an unlikely scenario as open wounds should be tended immediately in order to reduce the risk of other infections. The risk of a bacterial infection would be higher than an HIV infection.
  • Blood contact onto mouth or eyes – again possible but extremely unlikely unless you happen to be in a horror movie.
  • Dried blood – although HIV can survive in dried blood for several days, the environment has to be favourable and transfer this way is very very unlikely.

No risk of HIV transmission:

  • Breathing the same air as someone.
  • Touching a toilet seat or door knob.
  • Drinking from a water fountain.
  • Hugging, kissing or shaking hands (although kissing may transfer fluids the level of virus in saliva is so low as to make the risk negligible).
  • Sharing utensils.
  • Sharing gym equipment.
  • Skin to skin contact with an HIV positive person even if they happen to have fluid of unknown origin on them (particularly applies to commercial sex workers).
  • Biting or scratching that does not break the skin or draw blood.
  • Essentially, as mentioned above, fluid-fluid contact is necessary for transmission – if this hasn’t happened then there is no risk for HIV.

I hope this helps answer most questions that concern people over possible ways of HIV transmission – if new questions pop up I will try and add to this topic to help allay people’s fears.