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Feature Article

Human and animal bites: managing and preventing infection

STEPHEN MUHI, JUSTIN DENHOLM
OPEN ACCESS

Follow up

If patients are managed in the community, they should be educated regarding the symptoms of infection, should they develop (or worsen despite antibiotic ­treatment). Patients should be clinically reviewed between 24 and 48 hours after presentation, not only to assess the wound, but to monitor tolerance and compliance with antibiotic therapy, if initiated.

If empirical antibiotics were commenced, the results of Gram stain, aerobic and anaerobic cultures should be used to modify therapy based on organism and susceptibility testing.9 If intravenous therapy was initiated, switching to oral therapy is reasonable once the patient is stable. If the pathogen remains unknown, oral antibiotic therapy should be continued as for mild infection (Table 1), remembering that polymicrobial infections are predicted and should be covered broadly.

Immunocompromised patients, who are at increased risk of transmission and more severe illness after a bite, are particularly vulnerable. An Australian study recently found that more than half of immunocompromised patients surveyed owned a pet, most exhibited risky behaviour and 30% had been scratched or bitten by their pet.3 Immunocompromised patients with bite injury should be referred to hospital for assessment, and education remains the key to bite prevention in this group.

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Another important, but underappreciated, complication of animal bites that must be addressed at follow up is post-traumatic stress disorder (PTSD). In particular, children who have been attacked by a dog may suffer from PTSD later in life.71 Half of adults in one Australian survey lived in fear of future dog attacks, and many modified their behaviour towards dogs thereafter.72

Prevention

Although animals have become our much-loved companions, responsible pet ownership should always be encouraged. GPs have an important role in preventing bite wounds, and follow up represents an important opportunity to educate and offer vaccinations to people at risk of ­animal and human bites.

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Strategies to minimise harm in the future should include the following measures.

  • Behavioural measures. Avoid patting or touching dogs that demonstrate territorial behaviour and ensure that children are not left alone with dogs or other animals at risk of biting.73 Avoid dogs that are eating, sleeping or caring for puppies. Dogs should not be greeted with an outstretched hand, an unfamiliar dog should be allowed to smell the person’s hand first.73 Some breeds of dogs are known to have a higher attack rate despite training, so families should consider this when purchasing a new dog.73
  • Rabies and ABLV prevention. Avoidance of close contact with either wild or domestic animals is strongly encouraged, particularly for children travelling overseas. In Australia, unwell, injured or trapped bats and flying foxes should not be handled, and local wildlife rescue services should be contacted immediately for assistance. Pre-exposure vaccination should be offered to people at high risk of exposure, including those in occupations at high risk, risk-averse travellers and particularly children travelling to endemic areas.47
  • Tetanus immunisation. A booster dose should be offered to those who travel and are at risk of sustaining a bite wound if more than five years have elapsed since their last dose, especially if access to travel services will be difficult.47
  • Hepatitis B vaccination. Those at occupational risk of human bites, such as police, staff of correctional facilities and those who work with people with intellectual disabilities, may be at higher risk of human bites, and should receive HBV vaccination on employment.47
  • Immunocompromised and asplenic patients should be educated about the risk of life-threatening infection in the event of an animal bite, and the need to seek urgent medical attention.3

Conclusion

Animal bites are a growing public health risk, which may lead to serious injury and transmission of infection. The nature of the bite, the species of the animal and the conditions of the host are all factors to consider when managing a patient with a bite injury. Management includes immediate wound care, prevention of tetanus transmission and antibiotic prophylaxis. Prevention of infection with education, behavioural modification and timely vaccination are also key to reducing the risk of transmission of infection in the future.     MT

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COMPETING INTERESTS: None.

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Dr Muhi is an Infectious Diseases Registrar at the Victorian Infectious Diseases Service, Royal Melbourne Hospital. Associate Professor Denholm is Medical Director of the Victorian Tuberculosis Program; Senior Staff Specialist at the Victorian Infectious Diseases Service, Royal Melbourne Hospital; and Principal Research Fellow in the Department of Microbiology and Immunology, University of Melbourne, Melbourne, Vic.