Advocacy & Education: Blood-Borne Virus Infection via Spitting or Biting

As part of the Health+Law research partnership’s involvement in advocacy and education campaigns in relation to blood-borne viruses, Health+Law Chief Investigators Dr Anthea Vogl and Dr David Carter and Research Assistant Dr Elsher Lawson-Boyd authored a Brief on Blood-Borne Virus (BBV) Infection via Spitting or Biting.

In late 2022, South Australia became the first jurisdiction in Australia to criminalise the use of spit hoods – mesh devices that cover the face and are fixed at the neck, intended to prevent a restrained person from spitting or biting. They continue to be used in other jurisdictions, despite their use violating the United Nations Standard Minimum Rules for the Treatment of Prisoners – also known as the Nelson Mandela Rules. Spit hoods have been directly implicated in numerous deaths in custody in Australia and overseas.

Proponents of spit hood use argue that by preventing spitting and biting they can stop the transmission of infections such as HIV and hepatitis. It is in this context that the brief, which summarises clinical and scientific literature about the transmissibility of HIV, hepatitis B and hepatitis C by spitting or biting, was written. In reviewing the current clinical and scientific evidence, the brief shows that transmission of serious blood-borne viruses by events of spitting or biting is so unlikely that attempting to justify the use of spit hoods on this basis is unfounded.

Because HIV transmission has been criminalised significantly more than hepatitis B and C transmission, there is a rich body of literature authored by clinical and scientific experts regarding the risks and circumstances of transmission. The brief reviews these resources and finds that three separate expert consensus statements from around the world each reach the conclusion that there is no possibility of HIV transmission from a single event of spitting.

The brief goes on to quote the highly endorsed international 2018 Expert Consensus Statement on the Science of HIV in the Context of Criminal Law, which sets out the unlikely conditions required for HIV transmission to occur from a bite:

‘the HIV-positive person must have blood in their mouth at the time of the bite, a sufficient amount of HIV must be present in the blood of the HIV-positive person, and the bite must be deep enough to penetrate the HIV-negative person’s skin, causing trauma and tissue damage. Even when all these conditions are present, the possibility of transmission during a single bite is negligible at most.’

Reviewing the existing clinical literature around the transmission of hepatitis B and C, the brief notes that the risk of transmission via spitting is very low for hepatitis B and negligible for hepatitis C. As for biting, risk of transmission is also low, especially when there is no blood in the saliva of the biter.

The brief supplements this summary with a useful table from ASHM’s 2015 ‘Police and Blood-Borne Viruses’ guide (reproduced below) which sets out the risk of transmission in various circumstances for these viruses.

Further reading

Brief by Health+Law authors, Dr David Carter, Dr Anthea Vogl and Dr Elsher Lawson-Boyd: Brief on Blood Borne Virus (BBV) Infection via Spitting or Biting

Joint statement by Hepatitis Australia and ASHM: Joint Statement: Hepatitis B and hepatitis C are not transmitted through saliva | Hepatitis Australia