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Risk of HIV transmission by exposure type

Authoring team

transmission risk by exposure type

The risk of HIV transmission depends on the exposure and degree of viraemia of the source.

  • needlestick injuries
    • occurs following a needlestick injury with a needle contaminated with blood from a source known to have HIV
    • in healthcare setting source patient (serology) known
      • risk of becoming infected with HIV is thought to be between 0.1% and 0.36%
      • increased risk if large gauge needle, hollow needle, deep injury, visible blood on the device, needle was in patient "s artery/vein, or if the source patient has AIDS (or terminal illness).
    • in healthcare setting source patient unknown or unable to test source
      • risk assessment required of the type of injury and the likely infection status of the source

    • community needle stick
      • risk is more difficult to estimate and the exact incidence of needlestick injuries and the transmission rate is unknown
      • overall low risk and requires a risk assessment of the type of injury, location of the discarded needle (for example if discarded in a location where people who inject drugs are known to inject), likely age of the discarded needle and the background prevalence of HIV in the local population

    • post-exposure prophylaxis (PEP) is thought to reduce seroconversion by up to 81%

  • mucous membrane and non-intact skin exposure to blood - the risk is very low
    • risk for transmission of HIV via mucous membrane exposure is estimated to be 0.09%

  • intact skin exposure to blood - no risk

  • human bites
    • very low risk
    • risk assessment required
    • only risk if blood in the mouth of the biter, and significant injury. No risk if no blood in mouth of biter, and exposure to saliva only
    • if source co-infected with HCV, HCV transmission more likely than HIV transmission

  • sexual exposure
    • risk of transmission of HIV following sexual exposure depends on
      • the type of exposure
      • the viral load of the source the susceptibility of the host
      • the presence of sexually transmitted infections in either the source or the recipient
        • if the index partner also has a genitourinary infection, for instance, the risk of transmission is approximately doubled.
        • if the recipient has a genitourinary infection, the risk of acquiring HIV is also elevated

    • heterosexual exposure (general)
      • if source on antiretroviral therapy with suppressed viral load transmission rate = 0 (if viral load < 400 copies/ml)
      • increased risk if source patient has recently seroconverted, e.g. within 2.5 months of seroconversion risk of transmission is estimated to be 0.0082/coital act

    • receptive vaginal intercourse
      • overall risk is 1 in 1000, which is increased in the presence of cervical ectopy, genital tract trauma, menstruation, genital ulcerative disease (in either partner), infectious syphilis and pregnancy
      • male circumcision reduces HIV acquisition

    • insertive vaginal intercourse
      • overall risk is 1 in 1219

    • men who have sex with men (MSM) unprotected receptive anal intercourse
      • overall risk is 1 in 90
      • increased risk if there is ejaculation within the rectum.
      • the PARTNER study has demonstrated zero transmissions in HIV serodiscordant couples where the HIV positive individual is on effective antiretroviral therapy

    • MSM unprotected insertive anal intercourse
      • overall risk is 1 in 666
      • the PARTNER study has demonstrated zero transmissions in HIV serodiscordant couples where the HIV positive individual is on effective antiretroviral therapy

    • orogenital contact
      • overall very low risk, estimated to be <1 in 10,000 for both receptive and insertive oral sex

Reference:


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