HIV transmitted by human bite

On Wednesday, at the Ninth Retroviruses Conference in Seattle, the first unequivocal case of HIV transmission as the result of a human bite was presented.

The case involved a 31 year old HIV-positive man who bit his 59 year old mother on the hand during a seizure. The man, who had been previously unaware of his HIV status, was subsequently diagnosed with neurotoxoplamosis. Blood was present in the source patient's mouth since he had bitten his tongue and his mother's hand required stitching when she was taken to hospital.

Twenty-seven days following the incident the woman presented with fever and HIV antibody tests at that time were negative. Thirteen days later (40 days following the exposure incident) she was again tested for HIV infection by two ELISA (enzyme linked immunosorbent assay) tests, and a Western Blot test. The double ELISA testing strategy involved one sensitive and one less sensitive test and was deployed to detect recent HIV infection.

The less sensitive ELISA produced a negative result whilst the sensitive 'detuned' assay was found to be positive and this confirmed recent infection.

Researchers were also able to confirm epidemiological relatedness of the viruses infecting the individuals involved in the accident.

Presenting the poster, Dr Ricardo Diaz of the Federal University of Sao Paolo told aidsmap that "It was a shame the man's viral load had not been ascertained at the time of the bite, but it is anticipated that it was high, since the first measurement that was taken a few weeks after beginning antiretroviral treatment was 30,000 copies".

The authors commented "Although the possibility of transmission by human bite seems to be negligible because of the number of infecting particles and the inhibitors in saliva, cases with blood in the biter's mouth may deserve special attention".

In hospital environments, especially where healthcare workers are managing psychiatric, neurological, paediatric or combative patients this sort of exposure could be minimised by the use of gloves or arm protection.