HIV Transmission

Understanding HIV Transmission - How HIV is Passed from Person to Person

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How is HIV Trans­mit­ted between People?

HIV can only be trans­mit­ted from one part­ner to anoth­er by way of a few select bod­i­ly flu­ids, includ­ing blood, semen, vagi­nal flu­ids, rec­tal flu­ids and breast milk from an HIV pos­i­tive indi­vid­ual. The flu­ids list­ed need to come into con­tact with mucus mem­branes, dam­aged tis­sue, or direct­ly inject­ed into a person’s blood­stream via a non-ster­ile syringe or needle.

  • As an HIV pos­i­tive individual’s viral load decreas­es, their chances of pass­ing on the dis­ease decrease as well. This is a strong rea­son why ear­ly test­ing, ear­ly diag­no­sis, and a strict anti­retro­vi­ral ther­a­py reg­i­men is so important! 
  • Though homo­sex­u­al men are still among the high­est demo­graph­ic for HIV trans­mis­sion in the Unit­ed States, cas­es of infect­ed female to female trans­mis­sion are very rare in comparison.
HIV Transmission

Unpro­tect­ed Sex

In the US, recep­tive anal sex is the high­est risk behav­ior for HIV trans­mis­sion, anal sex being the high­est risk activ­i­ty. Vagi­nal sex is less risky, but unpro­tect­ed vagi­nal sex with an HIV pos­i­tive part­ner is still a very high risk behavior.

Oral Sex (Rare)

Though trans­mis­sion is pos­si­ble, it’s very rare for part­ners to con­tract HIV dur­ing oral sex. In the­o­ry, it’s pos­si­ble if the HIV pos­i­tive man ejac­u­lates in the woman’s/partner’s mouth, or if both par­ties exchange blood from open sores.

Infect­ed Blood Transfusions

It’s pos­si­ble to trans­mit HIV through infect­ed blood trans­fu­sions or infect­ed organ trans­plants, although this type of trans­mis­sion has become very rare. Where this type of trans­mis­sion was more com­mon dur­ing the ear­ly years (mid 80’s) of HIV, blood dona­tions and organ trans­plants are always very thor­ough­ly screened these days. 

Dirty/​Non-Ster­ile Needles

Since HIV is trans­mit­ted via blood, shar­ing needles/​syringes with an infect­ed per­son can eas­i­ly cause infec­tion. Believe it or not, HIV can live in a used nee­dle for up to 42 days! 100% ster­ile nee­dles are only found in a ster­ile med­ical envi­ron­ment, and only used once before being dis­posed of.

Pre-Chewed Food

This cir­cum­stance has only ever been known among mother/​infants, and is obvi­ous­ly a very rare cir­cum­stance. When infect­ed blood from a caregiver’s/mother’s mouth mix­es with food while chew­ing, the chances of spread­ing HIV rise.

Bite Wounds

HIV can be spread if bit­ten by a per­son pos­i­tive for the dis­ease. There were only a lim­it­ed num­ber of cas­es, and each involved severe tis­sue dam­age lead­ing to open wounds. There haven’t been any cas­es of trans­mis­sion when the skin hasn’t been broken.


HIV can also be spread from moth­er to child dur­ing preg­nan­cy, child­birth, or be trans­mit­ted from the moth­er to the child when breast­feed­ing, though this is a less com­mon method of trans­mis­sion com­pared to those above.

Today, any physi­cian will rec­om­mend sim­ple test­ing to ensure the moth­er does not have an infec­tion, and be able to prop­er­ly pre­pare if she does. Quick treat­ment and ear­ly detec­tion has dras­ti­cal­ly low­ered the amount of babies born in the US with the virus.

Con­t­a­m­i­nat­ed Objects

It’s pos­si­ble to con­tract the virus from an acci­den­tal (con­t­a­m­i­nat­ed) nee­dle stick, or a scrape from a sharp object with con­t­a­m­i­nat­ed blood on it. This risk lies main­ly with health care work­ers, however.

HIV Can’t Be Trans­mit­ted By or Con­tract­ed From:

  • Sali­va, sweat or tears
  • Water or air
  • Insects or pets
  • Toi­let sur­faces, food & drinks
  • Closed mouth kissing
    • It is extreme­ly rare for HIV to be trans­mit­ted by open mouth kiss­ing, and only if the HIV pos­i­tive par­ty has open, bleed­ing sores in their mouth. The virus can’t be trans­mit­ted via saliva.

HIV Out­side of the Body

Though HIV can live with­in a dirty/​used nee­dle for up to 40+ days in cer­tain con­di­tions, it doesn’t sur­vive well out­side the body, and can’t repro­duce with­out a human host. The virus can’t be trans­mit­ted, trans­ferred or spread by:

  • Insects, such as mos­qui­tos, lice or ticks
  • Sali­va, sweat or tears
  • Unbro­ken skin to skin con­tact, such as hug­ging or shak­ing hands
  • On the sur­face of cloth­ing, with­out the pres­ence of blood
    • HIV can’t be spread either to or con­tract­ed from any ani­mals (out­side of humans) or pets.
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