Zoonotic Diseases

Laurie Anne Walden, DVM

Zoonotic diseases, or zoonoses, are infections spread from animals to people (and vice versa). Many zoonotic diseases are transmitted by insects, wildlife, and livestock, and some are carried by pets.
 
Controlling zoonotic disease is a cornerstone of One Health, the concept that human health, animal health, and the environment are all linked. July 6 is World Zoonoses Day and is also the anniversary of the day Louis Pasteur administered the first successful rabies vaccination to a person (July 6, 1885).
 
How to reduce your risk
Preventive care for pets helps keep everyone in the family safe. The chance of contracting a zoonotic disease from a dog or cat is low if you take proper precautions. Zoonotic infections are also spread by contaminated food, insects, ticks, farm animals, birds, reptiles, and rodents. Young children, older adults, and people with compromised immune systems are at higher risk than others.
 
These measures can lower your risk:

• Wash your hands after being around animals or handling their food. Soap and water are best; use alcohol-based hand sanitizer if soap and water are not available.
• Keep your pets' vaccinations up to date.
  
• Give your pets parasite preventives all year round and have them tested regularly for parasites. (This is why your veterinarian’s office asks for your pet’s stool sample.)
• Do not feed pets raw eggs or raw meat diets.
• Handle food safely to prevent food poisoning.
• Protect yourself against insect and tick bites.

 
Find out more at the Centers for Disease Control and Prevention (CDC) website.
 
Zoonoses in companion animals
Many zoonotic diseases have been identified, and the CDC estimates that 75% of emerging infectious diseases originated in animals (often insects). Some of the most common zoonotic diseases in companion animals are listed below.
 
Bacteria

• Salmonellosis can be transmitted through contaminated food. Outbreaks have also been linked to reptiles, poultry, and pet food. Salmonellosis is the reason small turtles cannot be sold as pets in the United States.
• Listeria and Escherichia coli can also contaminate food. One study showed high levels of bacterial contamination in frozen raw diets for pets. Others have shown that dogs fed raw diets have increased risk of antibiotic-resistant bacteria and of shedding disease-causing bacteria into the environment.
• Bartonella species cause cat scratch disease and other (sometimes severe) diseases in humans. The type that causes cat scratch disease is transmitted to cats by fleas and is usually spread to people through cat bites or scratches, possibly when the wounds are contaminated with flea excrement.

 
Parasites

• Intestinal parasites like roundworms and hookworms are common in dogs and cats, especially puppies and kittens. They are spread to people by fecal-oral contact—that is, by ingestion of feces. Children are at risk if they eat contaminated dirt or put their hands in their mouths after handling infected animals. Hookworms can also be transmitted through contact of bare skin with contaminated soil. Puppies and kittens typically receive deworming medication during their first veterinary visits, and many heartworm preventives also control these intestinal parasites.
  
• Scabies, a type of mange, is caused by an external parasite that can also cause skin disease in humans.
• Toxoplasmosis is caused by a parasite transmitted by ingestion of undercooked meat or cat feces. It can also be transmitted to an unborn child if a woman becomes infected while pregnant. Pregnant women do not need to give up their cats, but it’s wise to take precautions during pregnancy to reduce the risk.

 
Other infectious agents

• Rabies is a viral disease that kills an estimated 59,000 people every year worldwide. It is transmitted through the bites of infected mammals. Nearly all of these human deaths are caused by dog bites. In the United States, where rabies vaccination for dogs and cats is mandated by law, rabies in humans is rare and is almost always caused by exposure to wild animals.
  
• Ringworm is a fungal skin infection that is spread by direct contact. People and animals can give ringworm to each other.

 
For more information:
Zoonotic diseases (CDC)
Zoonotic diseases and pets FAQ (American Veterinary Medical Association)
 
Photo by Lydia Torrey

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