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Reader reply to this post by email - From AI:

"there is a real but low risk that biting an attacker who bleeds into your mouth could transmit blood-borne infections (e.g., HIV, hepatitis B, hepatitis C) to you via your gums or any cuts/abrasions in your mouth.

Key factors that determine the risk

Factor

Details

Pathogen presence

Only if the attacker is infected. HIV prevalence in the UK general population is ~0.2%; hepatitis C ~0.3%. Risk is higher in high-risk groups (e.g., IV drug users).

Blood volume

Biting usually causes minor bleeding. HIV transmission requires a significant amount of infected blood (e.g., transfusion-level). Saliva dilutes blood rapidly.

Route of exposure

Gums are a mucous membrane, but intact gums are a poor portal. Transmission needs direct bloodstream access (e.g., open wound in your mouth or attacker’s blood entering your cut).

Virus survival

HIV is fragile outside the body; it dies quickly in saliva. Hepatitis B/C are hardier.

Estimated per-incident risk (if attacker is HIV+)

Needlestick (healthcare): ~0.3%

Human bite (blood in mouth): <<0.1% (case reports exist but are extremely rare)

No documented HIV cases from being the biter in assaults (only rare cases of bite recipient getting HIV from biter’s blood).

Practical advice if you bite and taste blood

Spit, don’t swallow – rinse mouth vigorously with water.

Clean wounds – antiseptic mouthwash if available.

Seek medical evaluation within 72 hours (ideally <2 hours):

Baseline HIV/hepatitis blood tests.

Consider post-exposure prophylaxis (PEP) for HIV (effective if started <72h; UK guidelines via A&E or sexual health clinics).

Hepatitis B vaccine/booster if not immune.

Report the assault – police can compel attacker testing (under UK law in serious cases).

Bottom line

Self-defence biting is legally justified (reasonable force) and the infection risk is negligible compared to the risk of death/GBH from the attacker. But if blood contact occurs, get urgent medical follow-up—not because transmission is likely, but because PEP can eliminate even tiny HIV risk."

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