Non-sexual HIV exposure or transmission

Non-sexual acts that most commonly provide the impetus for criminal cases of alleged HIV exposure or transmission include:

• spitting

• biting

• fighting

• wounding or threatening to wound with HIV-infected needles.

In all of these cases, the critical issue of whether there is any risk of HIV exposure relates to whether there is enough virus in the infectious fluid to potentially transmit HIV to someone.

Laboratory studies have found that saliva may contain HIV, and transmission via saliva is therefore biologically plausible. However, there is absolutely no epidemiological evidence to suggest that spitting on someone could expose them to enough HIV for infection to result. Levels of HIV in saliva are not high enough to allow transmission, even if the saliva comes into contact with a mucous membrane such as that of the eye. Spitting into someone's mouth would create the same risk as kissing – zero.

There may be an extremely small risk of HIV exposure if someone is spitting blood – for example, following a punch to the face – and this blood comes into contact with a mucous membrane or open wound. However, even in such a scenario, the blood is likely to be mixed with saliva, which, as discussed above, contains an enzyme that inhibits HIV. No cases of HIV transmission resulting from the spitting of blood have ever been reported.¹

Case study: Texas, United States – HIV-positive saliva as a 'deadly weapon.² In May 2008, a 42 year-old African-American homeless man living with HIV was sentenced to 35 years in prison by a Dallas court. His 'crime' was to spit at a police officer whilst stating that he was HIV-positive during his 2006 arrest for being drunk and disorderly. One of the reasons for the man's extremely long prison sentence was that he had done this several times before. The other reason was that the jury found that – despite scientific evidence presented to the court regarding the impossibility of infection through saliva – he had intended to harm the policeman using his saliva as a deadly weapon. The legal argument, as in most other HIV-related spitting cases in the United States, was focused on his intent rather than the actual harm spitting could cause. In contrast, it should be noted that only four of the United States' HIV-specific criminal exposure laws specify intent as one of the elements for guilt. The case was a cause for great concern for human rights and HIV advocates. Bebe Anderson of US civil rights organisation, Lambda Legal, noted: "Such criminal prosecutions confuse the public about ways in which HIV can be transmitted, and encourage discrimination and violence against those who have been infected with the virus. They also undermine the credibility and effectiveness of the criminal justice system as a central vehicle for encouraging respect for society's laws and protecting members of the public from preventable harm... Misconceptions about the ways in which HIV can be transmitted to another person are harmful for society at large, in part because they result in unfounded fears. Those misconceptions are especially harmful for people living with HIV, who continue to face stigma and discrimination, often based on those types of misconceptions."

HIV transmission by biting is possible but extremely unlikely. In order for transmission to take place there would need to be both exposure to blood and a route into the body for that blood. Just two case reports have documented infection via this pathway when deep wounds were exposed to a substantial amount of blood in the biter’s saliva.^3,4 However, there have been many more case reports where a bite by somebody with HIV did not result in HIV infection.⁵

Bleeding onto intact skin during a fight poses no HIV exposure or transmission risk. If HIV-infected blood comes into contact with broken skin, then HIV transmission is possible but still unlikely. The small number of case reports documenting HIV transmission via this route involved a significant amount of blood from the HIV-positive person, as well as large open wounds in the other person’s skin.⁶

The risk of HIV transmission from exposure to an HIV-infected needle outside healthcare settings has not been studied. However, despite media reporting that often suggests that the risk is great, there is not a single recorded case anywhere in the world of someone being infected with HIV through an attack with a needle, or by accidental wounding with a needle outside healthcare settings.⁵

Studies of healthcare workers have found the risk of HIV infection following a needlestick injury to be low. A large analysis of multiple studies estimated a per-needlestick risk of 0.23%, or 1-in-435.⁷ Risk of infection may be higher if the needle was used in an HIV-positive person’s vein or artery, if the HIV-positive person has a high viral load, if the needlestick injury is deep, or if blood is visible on the device that caused the injury.⁸