We all love our furry friends, but they can put you at risk for certain contagious diseases.

By Amanda Gardner
July 05, 2018

Dogs, cats, parrots, hamsters, and, for some people, even snakes and rats are often our best friends–and for good reason. Pet owners have lower blood pressure and less stress, and they exercise more, among other benefits. Kids who grow up with pets are actually less likely to end up with allergies.

But pets can sometimes also pass on diseases. Fortunately, it doesn’t happen often–and taking good care of your pet will help prevent the spread.

“Keeping your pet healthy helps keep you healthy,” says doctor of veterinary medicine (DVM) Casey Barton Behravesh, DrPH, director of the One Health Office at the Centers for Disease Control and Prevention (CDC).

Here are some diseases we hope your pet will never get and never pass on to you, along with some tips on how to make sure it stays that way. 

RELATED: The 4 Things Every Pet Owner Needs to Do to Keep Their Home Germ-Free

Ringworm

Ringworm is actually not a worm but a fungus.

Dogs and cats (especially kittens) are among the animals most often affected. The fungus may cause small areas of hair loss in your pet (or it may not cause any symptoms at all), but it can cause red, itchy spots with a scaly ring around them on your scalp, feet, groin, and other parts of your body.

“[Ringworm] is literally in a hair shaft so if [the animal] rubs against your skin, you can get little bumps or rings,” says Christine Petersen, DVM, PhD, director of the Center for Emerging Infectious Diseases at the University of Iowa’s College of Public Health.

Ringworm is typically treated with common antifungal medicines. The best prevention is making sure your pets get regular veterinary care.

Worms

“The main types of worms that people worry about [in pets] are roundworms and hookworms,” says Liz Vanwormer, DVM, PhD, an assistant professor at the School of Veterinary Medicine and Biomedical Sciences at the University of Nebraska, Lincoln.

They can be transmitted when you come in contact with pet feces and then touch your eyes or mouth, or when you walk barefoot on soil that’s been contaminated by your pet’s poop. Dogs and cats might have diarrhea or dark, bloody stool. In humans, roundworms and hookworms can cause symptoms like coughing, abdominal pain, or an itchy rash.

“Wash your hands after handling animals, gardening, or coming into contact with soil, and make sure you pick up poop and put it in the trash,” says Vanwormer. And don’t pick up the poop with your bare hands.

Of course, washing your hands frequently in general is one of the best ways to stave off the spread of all sorts of diseases, adds Behravesh.

Rabies

Rabies is rare in the U.S., but when it happens, it's devastating. Around the world, more than 59,000 people die each year after being infected with the virus, usually from a dog. “It’s completely preventable by [pet] vaccination,” says Petersen.

Rabies symptoms in pets can vary, but often include behavioral changes and paralysis.

If you do get bitten by a rabid animal, there is treatment. “You get a series of vaccines yourself,” says Petersen. “Instead of being preventive, it mounts a quicker response, and it almost always works.” Symptoms in humans include headache, fever, and weakness.

Rabies is actually more common in cats than dogs, says Bruno Chomel, DVM, PhD, professor of zoonosis at the University of California Davis School of Veterinary Medicine. “People are less likely to get their cats vaccinated, and cats are more likely to be active at night and encounter wildlife, especially raccoons and skunks,” he says.

Keep your pet's rabies and other vaccinations up to date.

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Cat scratch fever

Cat scratch fever or cat scratch disease is caused by a bacterium called Bartonella henselae that can lurk in cat saliva and in fleas that live on cats. (A related bacterium, Bartonella chomelii, is named after Bruno Chomel but is found in cattle and is not passed to humans.) Not surprisingly, cat scratch fever spreads from felines to humans by scratches, as well as from bites or if a cat licks an open wound on a human.

Cat scratch disease often causes vague symptoms including exhaustion, joint aches, and fever and has been mistaken for chronic fatigue syndrome, says Petersen. Some people also get a blister where they were scratched or bitten.

Don’t play rough with your cat and cover any open wounds you may have.

Parrot fever

Yes, there is such a thing. The official name of this bacterial disease is psittacosis and it can be passed on by not only parrots, but other birds too, like turkeys and pigeons.

Parrot fever is caused by a species of the chlamydia bacteria, but this one isn’t related to the sexually transmitted infection in people, says Petersen.

Humans can contract the disease by inhaling spores from the dander of an infected bird or from bird droppings. Symptoms are like a “really bad pneumonia,” says Petersen. Birds may have symptoms like diarrhea or poor appetite, but they can still spread the disease even if they have no symptoms.

RELATED: 6 Ways to Control Pet Allergens in Your Home

Tick-borne diseases

Lyme disease may be the most famous (or infamous) tick-borne disease and one that is largely confined to Northeastern states, but there are plenty of others that present risks all over the country.

Pets can’t spread these diseases to humans themselves, but they can bring ticks into the house and increase your risk, says Petersen. Cats are the more common culprits, she adds. “Because cats go out and hunt things, they’re more likely to get ticks that have disease on them.”

“The best way to prevent it is to protect the animal,” says Petersen. “There are ticks everywhere in the United States.”

Perform regular tick checks and talk to your vet about the best way to safeguard your pet.

RELATED: 11 Ways to Protect Yourself (and Your Pets) From Ticks

Salmonella

Salmonella bacteria are usually associated with food-poisoning outbreaks from contaminated eggs or meat, but pets can also pose a threat.

“People who have reptiles, amphibians, or rodents are at risk,” says Behravesh. “Many animals can appear perfectly healthy and happy, but they’re shedding bacteria. Little children under 5, people with weakened immune systems, and senior citizens are most at risk.”

The most common symptoms are the same as those of food poisoning: vomiting, diarrhea, fever, and cramping.

Small turtles are a particular problem. “They’re shedding salmonella all the time,” says Petersen. Some areas have banned their sale as pets for this reason.

Wash your hands after handling your reptilian and amphibian pets, says Chomel, and “don’t put the reptile in your sink and then clean your veggies.”

Reptiles may not be the best pets for you if you are immunocompromised or have young children, who may not be diligent about hygiene. “They’re going to touch the animals and the ground and put their fingers in their mouth and get infected,” says Chomel.

Hedgehogs can also pass on salmonella (and ringworm), he adds. It’s also possible to contract salmonella poisoning from the feces of dogs and cats.

Toxoplasmosis

Toxoplasmosis can be spread through cat feces and is particularly dangerous for pregnant women as well as for people who have suppressed immune systems. Cats rarely show any signs of toxoplasmosis, but symptoms in people can mimic the flu, including muscle aches, fever, and headache.

“When a mom is infected with Toxoplasma gondii for the first time during her pregnancy, the parasite has the potential to be passed to the developing baby, which can lead to severe consequences including birth defects and eye problems after birth,” says Vanwormer. “That’s why pregnant women are warned not to change cat litter boxes.”

Cover children’s sandboxes to prevent cats and other animals from using them like a litter box.

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Influenza

Birds and pigs can sometimes pass on the flu to humans, but it’s not common.

“One of the concerns are with backyard poultry,” says Chomel. “Those poultry can get infected with avian influenza viruses.”

You’d have to be in very close contact with the animals, and the virus, once passed to a human, is not easily passed to another person. Avian flu has moved from poultry to humans in China, where people sell them live at markets, but, so far, there have been no severe illnesses in the U.S., says Behravesh.

Swine also carry flu, as do dogs and cats, but the risk of transmission is extremely low.

RELATED: A New Study Says 'Dog Flu' Could Be the Next Swine Flu. How Worried Should You Really Be?

Plague

The plague can be transmitted by prairie dogs kept as pets, as well as dogs and cats.

“Cats are very susceptible and will develop the same type of plague that humans develop,” says Chomel. Symptoms can include headache, fever, and chills. “The big concern with cats having the plague is that they can transmit it by direct contact and breathing, but you have to be very, very close to the cat–less than three feet,” he says.

Cats and dogs can also bring home fleas that carry the plague.

Hantavirus

Hantavirus is usually transmitted by rodents, generally wild ones. “The classic scenario is where somebody is cleaning out an area with rodent feces,” says Petersen. “As they’re cleaning, the virus gets aerosolized, and they breathe it in.

A recent U.S. outbreak of a type of hantavirus called Seoul virus was traced to pet rats but didn’t spread too far before it was stopped. “That was the first time we saw such an outbreak in the United States,” says Behravesh.

Symptoms of hantavirus include fever, muscle aches, and feeling tired. As it progresses, you can have shortness of breath, coughing, and fluid filling the lungs. About 38% of people with hantavirus die of it.

RELATED: This Woman Died From Hantavirus—a Rare Infection Initially Mistaken for the Flu

Pasteurellosis

Pasteurella is a bacterium commonly found in the mouths of dogs and cats that can be passed on through bites and scratches. As many as half of infected dog bite wounds contain the bacteria.

“A few hours after the bite, it gets really painful, very swollen,” says Chomel. It can lead to a skin infection known as cellulitis.

“Pasteurellosis responds well to antibiotics,” he says. If you are bitten or scratched by a cat or dog, wash the wound thoroughly and contact your doctor. You may need a tetanus shot or he or she may want to rule out rabies.

Hepatitis E

There are different strains of hepatitis, and most are not transmitted by animals. But hepatitis E, though more commonly picked up through contaminated drinking water and food, has also been spread by pet pigs.

In one case documented in France, a 41-year-old patient developed fatigue about two months after being given a baby pet pig. The patient would pet the pig, who came in and out of the house, and also change its litter. Lab tests revealed that both pig and owner were infected with hepatitis E.

“It has to be very close contact,” says Chomel. “Don’t sleep with your pet pig.”

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Capnocytophaga

This is bacteria transmitted by dog or cat bites. “It’s not very common, but when it occurs, it [can be] really bad,” says Chomel.

It’s more likely to be severe in people who have weakened immune systems. “The first reported case was in the 1970s and was a veterinarian bitten by a dog,” he says. “The veterinarian had been in a car accident and had had his spleen removed.”

Capnocytophaga won't make a pet sick–but it can cause fever, diarrhea, vomiting, headaches, and other symptoms in people. The infection can progress to blood poisoning, Chomel says, and about 30% of people who get infected die.

Campylobacter

Campylobacter is one of the most common causes of diarrheal illness in the world. Infection with the bacteria usually comes through contaminated food or water, but you can also get it from coming into contact with pet feces.

That was the source of an outbreak that infected 113 people in 17 states recently. The common link? Petland stores. All of the people were employees, customers, or had visited a home with a new puppy from Petland.

Generally, campylobacteriosis is not life-threatening, but it can cause severe illness if you’re very young, very old, or have a weakened immune system. Pet-store pets have a higher likelihood of carrying campylobacter simply because they are around other animals. Wash your hands after playing with one–and make sure your own pet is healthy and happy so as to reduce its risk of getting infected.

Monkeypox

More common in Africa, there was one monkeypox outbreak in humans in the U.S. in 2003. There were 37 confirmed and 10 probable cases in six states in the Midwest.

The disease, which causes fever and a rash in animals and humans, was traced to a shipment of rodents from Ghana that had been housed near a group of prairie dogs. The prairie dogs were then sold as pets, and several owners contracted the pox either through being bitten or scratched, touching the animal or its bedding, or cleaning out a cage.

There is no current treatment for monkeypox; instead, outbreaks are controlled using the smallpox vaccine and antiviral medicines.