Pet Health Library

Zoonotic Diseases

Background

Zoonotic diseases or zoonoses are diseases that can be passed from animals to humans. Zoonoses are caused by microorganisms such as bacteria, viruses, parasites, or fungi. These microbes spread between animals and people in the following ways:

  • Direct contact – spread directly through immediate contact with an infected animal, including its saliva, blood, urine, mucus, and feces. Infections can spread through a direct touch, bite, or scratch.
  • Indirect contact – spread indirectly through contact with contaminated areas or objects, such as soil infected by an animal’s feces or a pet’s food dish contaminated by bacteria.
  • Vector-borne – spread through a “middleman” that carries the disease from animals to people. Common vectors that spread disease between people and pets include fleas, ticks, and mosquitos.
  • Foodborne – spread through eating contaminated food, such as raw or undercooked meat, unpasteurized milk, or fresh produce contaminated by the feces of an infected animal. Either pet food or human food can be contaminated and cause illness.
  • Waterborne – spread through drinking or direct contact with water contaminated by the urine or feces of an infected animal.

It is possible for an animal to be infected with a microorganism and show no signs of illness. However, the animal will still be able to pass along the microorganism to people and cause illness or vice versa.

Risk Factors

The risk of infection from certain zoonotic diseases can vary widely based on a person’s or pet’s contact with animals and the surrounding environment. However, certain groups of people are more at risk of contracting zoonoses and falling ill, which include:

  • Children under the age of 5
  • Adults over the age of 65
  • Immunocompromised individuals
  • Pregnant women

Types of Zoonotic Diseases

  • Campylobacter – food or water contaminated with the bacteria Campylobacter can cause gastroenteritis, or inflammation of the digestive tract.
  • Canine Influenza (Dog Flu) – like the human flu, canine influenza, or “dog flu”, is very contagious. It can easily be spread to other dogs through natural behavior, such as barking or sneezing, or from shared toys or water bowls. While humans can’t catch dog flu, humans can spread it to other dogs if they come into contact with an infected dog or item and then touch another dog.
  • Canine Scabies (Mange) – mites are a type of parasite that cause mange, which is characterized by irritated skin, itching, hair loss, and inflammation. The mite that causes canine scabies is called Sarcoptes scabiei var canis and can be passed to both dogs and people.
  • COVID-19 there is some evidence indicating that pets can become infected with SARS-CoV-2, the virus that causes COVID-19 in humans, but these cases are rare. Cats are more easily infected than dogs and may show signs of respiratory illness. There is no evidence at this time that dogs or cats can be a source of infection in humans.
  • E. coli – food or water contaminated with the bacteria E. coli can cause gastroenteritis (inflammation of the digestive tract), fever, and abdominal pain in both humans and pets. The source of contamination is typically from the feces of an infected animal.
  • Intestinal Parasites – most internal parasites live in the intestines and require a fecal analysis for proper diagnosis. Parasites that can infect both people and pets include roundworms, hookworms, tapeworms, and Giardia.
  • Leptospirosis – a disease that can cause kidney and liver damage. It spreads through contact with the nasal secretions, urine, or saliva of infected animals. Rats, mice, squirrels, and other rodents are common carriers of the bacteria.
  • Lyme Disease – a bacterial infection caused by Borrelia burgdorferi transmitted through the bite of an infected tick. It can cause inflammation of the joints and both dogs and people are susceptible to developing the disease.
  • Rabies – a deadly infection caused by a virus secreted in saliva that attacks the nervous system. Unvaccinated dogs who spend time outdoors, especially around wild animals, are at the greatest risk for contracting rabies.
  • Rat Bite Fever this zoonotic disease is caused by one of two different bacteria found in the normal biome of a rat’s respiratory tract. Rats typically do not show signs of illness, but people can become infected through a rat bite or exposure to the rat’s urine, feces, or saliva.
  • Rocky Mountain Spotted Fever – a bacterial infection caused by Rickettsia rickettsii transmitted through the bite of an infected tick. Dogs and humans are both susceptible to developing the disease. Despite its name, this disease most often occurs east of the Mississippi River States.
  • Salmonella – food or water contaminated with the bacteria Salmonella can cause gastroenteritis (inflammation of the digestive tract), fever, and abdominal pain in both humans and pets. The source of contamination is typically from the feces of an infected animal. Pet birds and reptiles can also carry the bacteria without appearing ill.
  • Toxoplasmosis – an infection caused by a parasite called Toxoplasma gondii that is found in cat feces and undercooked meat. Pregnant women and immunocompromised individuals are most at risk for developing health problems after exposure to the parasite. Cats can become infected after eating infected prey or undercooked meat that contains the parasite.

Managing the Disease

If Your Pet is Diagnosed with a Zoonotic Disease:

  • Talk with your veterinarian about how to keep your family and other pets in the household safe.
  • If possible, keep your sick pet in an area separate from any other pets and people in the household.
  • Wash your hands after any contact with your pet or objects in its environment, such as its bedding, toys, or food.
  • Sanitize the area your pet has used and, if necessary, get rid of contaminated objects.

Prevention

There are many steps pet owners can take to prevent the spread and contraction of zoonotic diseases in themselves and their pets.

Keep Your Pet Healthy

  • Keep your pet’s vaccinations up-to-date and schedule regular wellness visits with your veterinarian.
  • You can protect your pet against parasites such as fleas, ticks, and mosquitos through various preventatives such as flea/tick collars, oral products, or spot treatments, and by checking their coat after being outdoors. Talk with your veterinarian to see which preventatives are right for your pet.
  • Protect yourself from fleas, ticks, and mosquitos by using an insect repellant and wearing light-colored clothes that cover the body to better spot potential parasites when spending time outdoors.
  • If you live in a specific area or will be traveling somewhere new with your pet, talk with your veterinarian to see if you and your pet will have a greater risk of exposure to certain zoonotic diseases.

Practice General Hygiene

  • Wash your hands after touching or being around animals, particularly if you are about to eat. Always use soap and water if they are available. If not, use an alcohol-based hand sanitizer that contains at least 60% alcohol.
  • Clean up after your pet and wash your hands whenever handling their food, bedding, or waste before you eat.
  • Always use a bag and cover your hand when picking up after your dog.
  • Wear gloves and use a scooper when changing your cat’s litter box. Make sure to change the litter box daily to lower the risk of exposure to parasites.
  • Sanitize your cat’s litterbox with hot soapy water weekly or whenever excessively soiled.

Handle Food Safely

  • Try to prepare pet food in a separate area from where people’s food is prepared and avoid feeding your pet while in the kitchen.
  • Your pet should have their own designated food and water bowl that are washed daily in the dishwasher or with hot soapy water, ideally in an area separate from where human food is prepared and consumed.
  • Use caution when handling food, particularly raw or undercooked meat. Always refrigerate food properly and check the expiration dates before consumption. Wash dishes, utensils, and pans with hot soapy water after preparing raw meat for cooking

Practice Safety Around Animals

  • Avoid approaching or touching wild animals.
  • If you have the opportunity to interact with an animal in a zoo or farm setting, practice good hygiene by washing your hands after the animal encounter and avoid eating or drinking in the animal area.
  • Always supervise children 5 years of age or younger when they are interacting with an animal. Stop behaviors that could hurt the animal, such as your child tugging on the animal’s ears or tail, in order to prevent a bite or scratch. If you have a family pet, make sure your child doesn’t put their hands in their mouth after playing with your pet and teach them to wash their hands right after.
  • The CDC recommends that children under 5 years of age avoid certain animals to decrease the risk of exposure to harmful germs. These animals include:
    • Reptiles (lizards, snakes, turtles)
    • Amphibians (frogs, toads, news, salamanders)
    • Poultry (baby chicks, ducks)
    • Rodents (rats, mice, hamsters, gerbils, guinea pigs)

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The Animal Medical Center’s specialists in Internal Medicine are certified by the American College of Veterinary Internal Medicine. Areas of this specialty service include:

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