Public Release: 

Household pets can transmit infections to people

People with weak immune systems especially vulnerable

Canadian Medical Association Journal

Household pets can transmit infection to people, especially those with weak immune systems, young children, pregnant women and seniors, according to an article in CMAJ (Canadian Medical Association Journal). Health care providers and pet owners should be aware of this risk to prevent illness in vulnerable people.

Surveys suggest that the general public and people at high risk for pet-associated disease are not aware of the risks associated with high-risk pet practices or recommendations to reduce them; for example, 77% of households that obtained a new pet following a cancer diagnosis acquired a high-risk pet," states Dr. Jason Stull, assistant professor, Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio.

The review explains the types of infections, how infections are transmitted from pets, prevention and the role of health care providers.

"Studies suggest physicians do not regularly ask about pet contact, nor do they discuss the risks of zoonotic diseases with patients, regardless of the patient's immune status ," writes writes Dr. Stull, with coauthors Dr. Jason Brophy, Children's Hospital of Eastern Ontario (CHEO) and Dr. J.S. Weese, Ontario Veterinary College.

All pets can transmit diseases to people. For instance, dogs, cats, rodents, reptiles and amphibians can transmit Salmonella, multidrug resistant bacteria (including Clostridium difficile), Campylobacter jejuni and other diseases. Parasites such as hookworm, roundworm and Toxoplasma can also be transmitted. Infection can be contracted from bites, scratches, saliva and contact with feces. Reptiles and amphibians can transmit disease indirectly, such as via contaminated surfaces.

"Reptiles and amphibians are estimated to be responsible for 11% of all sporadic Salmonella infections among patients less than 21 years of age, and direct contact with such animals is not required for zoonotic transmission," write the authors. "In one study, 31% of reptile-associated salmonellosis cases occurred in children less than 5 years of age and 17% occurred in children aged 1 year or younger; these findings highlight the heightened risk in children and the potential for reptile-associated Salmonella to be transmitted without direct contact with the animal or its enclosure."

For healthy people, the risk of pet-associated disease is low, but vulnerable people are at risk, including newborns, children with leukemia and adults with cancer.

"Given the health benefits of animal ownership and the reluctance of patients to give up their pets, resources highlight the importance of following specific precautions," states Dr. Stull. "Patients at high risk and their households should have increased vigilance of their pets' health and take precautions to reduce pathogen transmission." Simple steps can dramatically reduce the risk.

Recommendations for reducing transmission of infection include:

  • wearing protective gloves to clean aquariums and cages and remove feces

  • proper handwashing after pet contact

  • discouraging pets from face licking

  • covering playground boxes when not in use

  • avoiding contact with exotic animals

  • regular cleaning and disinfection of animal cages, feeding areas and bedding

  • locating litter boxes away from areas where eating and food preparation occur

  • waiting to acquire a new pet until immune status has improved

  • regularly scheduling veterinary visits for all pets.

Physicians and other health care providers should enquire about pets and repeat questions in light of illness in vulnerable people, as well as advise on the risks of pet ownership and how to reduce risks of disease.

The authors also recommend that veterinarians can be a resource for physicians seeking more information on zoonotic infections and risks associated with unusual pets.

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