Zoonotic diseases are illnesses that can be transmitted from your pet to you through bites, scratches, saliva, feces, or urine. Though they rarely cause severe illness in people, it’s still helpful to be aware of some of the more common zoonotic diseases that can cause health issues in humans. 

Common Zoonotic Diseases of Cats and Dogs

It’s worth noting that anyone can catch a zoonotic disease. Some people are at higher risk, including:

• The elderly
• Pregnant women
• Young children
• Individuals with a weakened immune system

Campylobacter

Campylobacter jejuni and Campylobacter upsaliensis are bacteria that cause a bacterial intestinal infection known as Campylobacteriosis.

Infection and Signs

Pets can become infected by: 

• Ingesting contaminated water or food
• Contact with infected poop 
• Drinking unpasteurized milk
• Direct contact with infected animals
• Exposure to contaminated environments

If your pet has Campylobacteriosis, you may see:

• Abdominal cramping and pain
• Diarrhea that may contain blood or mucus
• Fever
• Lethargy
• Straining to poop
• Vomiting 

Diagnosis and Treatment

Campylobacteriosis is diagnosed by a DNA test or a culture and sensitivity test of your pet’s poop.

Many infections are mild and resolve on their own. Moderate to severe cases may be treated with antibiotics and medication for nausea and pain. Your pet may also get fluids to prevent dehydration and a highly digestible diet with added probiotics. 

Campylobacteriosis in Humans

People are infected by coming in contact with infected feces or contaminated bedding, bowls, or toys.

It can cause diarrhea, fever, and stomach cramps. Most infections resolve on their own, but treatment may be necessary for severe cases.¹ Contact your physician if you have been exposed. 

Cryptosporidiosis

This small bowel infection is caused by the parasite Cryptosporidium.

Infection and Signs

Pets and people become infected by ingesting something contaminated with the parasite, such as poop, water, food, or prey animals.

This disease can cause watery diarrhea; however, many pets do not show any signs of illness.

Cryptosporidiosis can be more serious, and even life-threatening, for puppies and immunocompromised dogs.

Diagnosis and Treatment

It can be difficult to diagnose, often requiring poop specimens to be sent to specialty labs.

The good news is that treatment isn’t needed for most cases. The illness resolves on its own. When necessary, there are a few medications effective in treating this disease. A highly digestible diet, fluids, probiotics, and other supplements can also be supportive.

Cryptosporidiosis in Humans

People with Cryptosporidiosis can have headaches, low-grade fever, nausea, stomach cramps, vomiting, watery diarrhea, and weight loss.² Symptoms can last up to about twenty days in healthy people.² Those with weakened immune systems often have more severe symptoms that last longer.

Salmonellosis

Salmonella causes the bacterial infection Salmonellosis, which typically affects the gastrointestinal tract.

Infection and Signs

Pets most commonly become infected by ingesting contaminated feces or something contaminated by feces, such as food or water. This can also serve as a transmission path to humans. Direct contact with infected animals or the ingestion of undercooked meat are also routes to infection.

Some pets may show no signs, but they can still shed the bacteria in their poop, which can infect other pets or people.

Kittens and puppies are more likely to show signs, including:

• Diarrhea
• Fever
• Change in appetite
• Lethargy
• Vomiting

Diagnosis and Treatment

Diagnosis can require a bacterial culture of poop and blood, as well as PCR testing.

Medical treatment for mild cases may not be necessary as they often resolve on their own. Supportive care at home is often all that’s needed, including rest, maintaining hydration, feeding a highly digestible and bland diet, and administering probiotics.

For more severe cases, pets may require hospitalization for supportive care, which can include intravenous fluids, anti-nausea medication, antibiotics, and other medications.

Salmonellosis in Humans

Salmonellosis causes symptoms such as abdominal cramps, diarrhea, and fever. Most recover without treatment; however, diarrhea can become so severe that hospitalization is necessary.³

Rabies

Rabies is a fatal viral disease found worldwide. 

Infection and Signs

Rabies is transmitted to dogs, cats, and humans through saliva and mucous membranes, such as getting bitten or scratched by a rabid animal or coming into contact with their eyes, nose, or mouth.⁴

Pets can exhibit a variety of signs, such as:

• Aggression
• Difficulty swallowing
• Excessive drooling
• Fearfulness
• Paralysis
• Seizures
• Staggering
• Being uncharacteristically affectionate

Diagnosis and Treatment in Pets and Humans

Unfortunately, no rabies test can be done on a living pet. Diagnosis is made through laboratory testing of brain tissue after the pet passes. 

There is also no effective treatment for rabies in people or pets once symptoms appear.⁵

The best way to prevent rabies is by keeping up with your pet’s vaccinations. If you think you are exposed to a rabid animal, contact your physician or go to the ER.

Intestinal Parasites (Roundworms and Hookworms)

Intestinal parasites, often referred to as “worms,” are common in dogs and cats. Roundworms and hookworms are just two types commonly found across the U.S.

Infection and Signs

There are various ways dogs and cats become infected with these intestinal parasites.

• Ingestion of soil, water, or poop contaminated with eggs or larvae
• Through the placenta of the mother (dogs only)
• Through milk while nursing 
• Licking contaminated fur, paws, or objects
• Ingestion of infected prey

If your pet has intestinal parasites, you may see:

• Anemia 
• Dehydration
• Diarrhea
• Dull coat
• Pale gums 
• Pot-bellied appearance
• Weight loss

Diagnosis and Treatment

Intestinal parasites are typically diagnosed through a routine fecal (poop) flotation test.

To treat intestinal parasites, your veterinarian will prescribe a dewormer. 

Monthly preventatives for heartworms, fleas, and ticks can help keep your pet parasite-free.

Intestinal Parasites in Humans

People can become infected with roundworms by swallowing eggs through contaminated soil, food, or unwashed hands. In fact, each year in the U.S., three to six million people are infected with the larvae of roundworms.⁶

Infection with hookworms generally occurs when hookworm larvae penetrate the skin, which can happen when people sit or walk barefoot on contaminated soil or sand.

Children are more vulnerable than adults since they put dirty objects in their mouths, play in playgrounds, and may eat dirt.

Roundworm infections in people may cause no obvious symptoms or harm, but some can cause damage to tissues and affect the nerves and eyes.⁷

Hookworms can cause inflammation, redness, and itchy tracks in the skin called cutaneous larva migrans. If they penetrate into deeper tissues, they can cause damage to the intestines and other organs.⁷

Treatment for people usually includes antiparasitic medication.⁸

Giardia

This is a common parasitic infection, particularly in dogs, that affects the gastrointestinal tract.

Infection and Signs

Pets are infected by ingesting food, water, soil, or objects contaminated with poop that contains Giardia cysts.

Some pets show signs of infection, such as:

• Abdominal discomfort
• Sudden diarrhea
• Soft or watery stool that may be foul-smelling with mucus
• Vomiting

Diagnosis and Treatment

Giardia can be diagnosed with a fecal flotation test.

Pets are treated with a specific antibiotic/dewormer combination typically and may need fluid therapy, antiemetics, and anti-diarrheal medications.

Giardia in Humans

People are infected by ingesting the parasite’s cysts after touching contaminated objects, food, water, soil, or surfaces.

Symptoms include various types of gastrointestinal distress and can last as long as six weeks.⁹

Treatment often isn’t needed, as symptoms may resolve on their own, but medication is available.¹⁰

Most Common Canine Zoonotic Diseases¹¹

• Campylobacter
• Cryptosporidiosis
• Salmonellosis
• Giardia
• Roundworm
• Hookworm
• Tapeworm
• Ringworm
• Leptospirosis
• Rabies

Most Common Feline Zoonotic Diseases¹²

• Campylobacter
• Cryptosporidiosis
• Salmonellosis
• Giardia
• Roundworm
• Hookworm
• Ringworm
• Toxoplasmosis
• Cat scratch disease
• Rabies

Should You Worry About Zoonotic Diseases?

It’s important to use caution if your pet has a zoonotic disease. Your best course of action is to bring your dog or cat to the vet for treatment and visit your doctor if you have any concerns.