Biting

  • Transmission by biting is extremely rare, but a handful of cases have been attributed to this activity.

A few cases of HIV transmission have been attributed to biting . In one case a five-year-old child infected with HIV by transfusion bit his eight-year-old brother.1 Infection was not detected until his death from AIDS three and a half years later. His brother was then discovered to be HIV-positive. There appeared to be no other explanation for infection: the brother had not received blood and had not been sexually abused to the knowledge of his parents, but his mother had noticed a bite mark on his arm about six months before the younger child died.

In a similar case, in 2000, a three-year-old child was bitten on the finger by her father, causing bleeding. The father had risk factors for HIV, dental caries and bleeding gums. The father was only diagnosed with HIV in 2004, with severe immunosuppression, just before his death. Following the father’s diagnosis, his wife tested HIV-negative, whereas their daughter was HIV-positive. There was no known history of sexual abuse or blood transfusion. However the viral strains of father and daughter were not compared.2

In another case, a man in the late stages of AIDS suffered a seizure and bit the finger of a neighbour who came to his aid. HIV antibody and antigen tests taken on the day of the incident were negative, but the man tested positive less than two months later. It is believed that the man with AIDS bit his tongue before biting his neighbour, and that blood was therefore present in his saliva.3

In a case in Florida, an HIV-positive woman with bleeding gums bit a 90-year-old man several times, causing extensive tissue damage and bleeding. The man tested negative for HIV antibody shortly after the incident and had seroconverted within 40 days. DNA sequencing showed a close genetic relationship between the HIV strains of the woman and the man, and the investigators were satisfied that they had not had sex together.4

In a further case, a 31-year-old HIV-positive man bit his 59-year-old mother on the hand during a seizure.5 The man, who had been previously unaware of his HIV status, was subsequently diagnosed with neurotoxoplasmosis. 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 using the STARHS methodology, which confirmed recent infection.

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

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.

A follow-up of thirty healthcare workers who cared for a patient with AIDS who bit them showed no cases of seroconversion.6

Related Links

References

  1. Wahn V et al. Horizontal transmission of HIV infection between two siblings. Lancet 2(8508):694, 1986
  2. Bartholomew CF et al. Human bites: a rare risk factor for HIV transmission. AIDS 20: 631-636, 2006
  3. Widmar L Transmission of HIV by human bite. Lancet 347: 1762-1763, 1996
  4. Liberti T et al. Blood-to-blood transmission of HIV via bite. Int Conf AIDS (abstract no. Mo.D.1728), 1996
  5. Andreo S et al. HIV-1 transmission by human bite. Ninth Retroviruses Conference, abstract 770-W, Seattle, 2002
  6. Tsoukas C et al. Lack of transmission of HIV through human bites and scratches. JAIDS: 1(5): 505-507, 1988
This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.