Outbreaks of illnesses linked to pets seem to be on the rise.
This month, CNN reported on an outbreak of campylobacteriosis, a bacterial infection, that was caused by contact with puppies sold by Petland stores.
So far, 39 people in seven states have fallen ill. Nine of them were hospitalized.
The puppy-borne campylobacter outbreak report came just weeks after small pet turtles were blamed for an outbreak of salmonella that has infected 37 people in 13 states since March, with 12 of those infected children age 5 and younger.
That animals in general and pets specifically can spread illnesses to humans isn’t a new phenomenon.
The FDA banned the sale of small turtles (with shells smaller than 4 inches) more than 40 years ago because of the established salmonella risk.
And domesticated dogs contracted rabies and then infected humans with the disease for decades before vaccination and animal control programs all but eradicated the disease in the United States.
In fact, only one to three cases of human rabies infection are reported in the U.S. annually.
The diseases that people get from animals are known as zoonotic diseases, or zoonoses. Today the likelihood of these types of contagions is quite slim.
“Put it in perspective,” Dr. William Schaffner, professor of medicine in the Division of Infectious Diseases at Vanderbilt University, told Healthline. “The risk of transmission from a domesticated animal is really pretty small.”
Still, it’s important to be aware of the risks of pet ownership — particularly for exotic animals — and to take precautions to keep you, your family, and your pets healthy.
The rise of zoonoses
Pets carry germs that make people sick, sometimes even when those same germs have no harmful effect on the animals themselves.
Essentially, the cohabitation of animals and humans has led to the exposure and proliferation of bacteria and microorganisms that would otherwise not take place.
“Many infectious diseases originate from pathogens, viruses, that are common in the animal population,” Schaffner said. “As the human population increases and we move into areas previously only sparsely inhabited, the opportunities for contact with these virus-carrying animals increases. Transmission of these pathogens to us is an accident, of sorts, but the viruses affect us.”
Similarly, pets are basically wild animals that have been introduced into our environment.
“With pets, it’s the reverse,” Schaffner said. “Turtles don’t normally live in houses, but if they’re bred to be pets, then we touch them, we contaminate our hands, and then we touch our mouths and noses.”
“The turtle has a thousand-year relationship with salmonella, but domestication has brought the turtle and salmonella into homes.”
Why these pathogens affect humans but have no effect on their animal hosts is based in evolution.
“We don’t have a symbiosis with these organisms,” Dr. Dana Hawkinson of the Infectious Disease Division at the University of Kansas Health System told Healthline. “We’re not colonized by them. Some organisms cause disease in us because we don’t have the typical defense mechanisms to live in a symbiotic relationship with them.”
Certain human populations are more vulnerable to zoonoses than others.
“People that are more susceptible to illnesses and infections are people with weakened immune systems — those with autoimmune disease or are undergoing chemo,” said Dr. Casey Barton Behravesh, director of the One Health Office at the National Center for Emerging and Zoonotic Infectious Diseases of the Centers for Disease Control and Prevention (CDC).
Children 5 and younger and adults 65 and older are also at increased risk.
“Kids engage in more risky behavior such as licking animals,” said Behravesh.
Pregnant women are susceptible to adverse effects from contamination by certain germs.
“But even healthy people can get sick,” Behravesh told Healthline.
Here’s a list of the more common pet-borne diseases and the type of pets typically associated with the illness or infection.
Additional information, including updates about current zoonotic disease outbreaks, is available at the CDC’s Healthy Pets Healthy People site.
Ringworm (dogs, cats)
Ringworm, a skin and scalp disease caused by a fungus, is passed from animal to animal and animal to human by contact.
It can also be transferred by touching an object or surface that came in contact with the infection.
People with ringworm develop a scaly, reddened, circular, and itchy rash.
Ringworm infection of a pet may not be obvious, but puppies and kittens may show signs — often hairless areas with scaling, crusting, and redness.
Pets with potential ringworm should be taken to the veterinarian.
Campylobacter (dogs, cats)
Campylobacteriosis is a disease caused by bacteria that is sometimes passed to humans via contact with the feces of infected dogs and cats.
Symptoms of the human infection are diarrhea, cramping, abdominal pain, and fever within two to five days after exposure to the organism.
Typically, no treatment is necessary, as the symptoms pass within a week.
Cat-scratch disease (cats)
As the name implies, humans become infected with cat-scratch disease (CSD) when an infected cat breaks a person’s skin by biting or scratching, or licks a person’s open wound.
Although 40 percent of cats carry the infection-causing bacteria at some time in their lives, kittens are more likely to bite or scratch and therefore pass the infection on to humans.
The bacteria can cause a mild but painful infection at the area of the wound, making it swell and produce lesions.
A person with CSD may also develop a fever, headache, poor appetite, and exhaustion.
Should your pregnant partner attempt to clean the litter box, please stop her.
She may contract toxoplasmosis and pass the disease on to her unborn child, causing birth defects affecting the nervous system and eyes.
A single-celled parasite causes toxoplasmosis.
Cats become infected by eating rodents, birds, or other small animals infected with the parasite.
The parasite is then passed via the cats’ feces on to their human owners, who accidentally ingest the microscopic parasites during litter box cleaning.
E. coli (petting zoo animals)
The bacteria Escherichia coli (E. coli) is a normal (and important) part of humans’ intestinal tracts, but some kinds of E. coli are harmful and can cause disease — most commonly E. coli O157.
Symptoms of infection are diarrhea, fever, abdominal cramps, nausea, and vomiting.
Young children are more likely to have severe problems from E. coli O157, including kidney failure and death.
The bacteria can be passed directly to people from the skin, fur, and feathers of contaminated animals, typically cows (especially calves), goats, sheep, and deer.
Salmonella (amphibians, reptiles)
Turtles aren’t the only potential pets that can carry and pass on salmonella infections.
Geckos, bearded dragons, frogs, and other creepy, crawly animals can carry the illness-causing bacteria.
Though most people contract salmonellosis (a salmonella infection) from contaminated food, contact with infected animals (such as small turtles) can also cause the illness.
According to the CDC, salmonella infection hospitalizes approximately 19,000 people and is responsible for 380 deaths every year in the United States.
Salmonellosis symptoms are diarrhea, fever, and abdominal cramps occurring between 12 and 72 hours after infection.
Most people recover without treatment within four to seven days, although some people may have diarrhea so severe they need to be hospitalized.
Although rodents aren’t common pets in the United States, there are enough pet rats in the country to require a CDC investigation into the outbreak of the rodent-borne Seoul virus that infected 17 people in seven states earlier this year.
People contract the virus from contact with the urine, droppings, or saliva of infected rodents, specifically the brown or Norway rat.
People who become infected with the virus often exhibit mild or no symptoms. However, some will develop a form of hemorrhagic fever with renal syndrome, with death occurring in approximately 2 percent of these cases.
The CDC recommends that rat owners and breeders inspect proof of a rat’s infection status before accepting new rats into existing colonies.
Psittacosis (exotic birds)
Parrot fever, as psittacosis is familiarly known, is an infectious disease caused by bacteria and contracted by humans from infected parrots (macaws, cockatiels, and budgerigars) as well as from infected pigeons, sparrows, ducks, hens, gulls, and other species of bird.
Human infection is usually acquired by inhaling dried secretions from infected birds, making bird owners, aviary and pet shop employees, poultry workers, and veterinarians at-risk groups.
Fewer than 10 confirmed cases are reported in the U.S. each year.
Psittacosis can affect the lungs and may cause pneumonia. Other symptoms are fever, soreness, headaches, and a dry cough.
Lymphocytic choriomeningitis (mice, hamsters)
Lymphocytic choriomeningitis (LCM) is a rodent-borne viral disease primarily hosted by common house mice, but hamsters and other types of pet rodents can become infected with the virus from wild mice at the breeder, pet store, or home.
The virus is transmitted to humans via contact with urine, feces, saliva, or blood of infected pet mice or hamsters.
Although most infections result in few or no symptoms, those persons who do become ill typically have fever, malaise, lack of appetite, muscle aches, headache, nausea, and vomiting.
A second phase of illness can and may include meningitis, encephalitis, or meningoencephalitis. Pregnant women who become infected may pass the infection to their fetuses, possibly causing fetal death or birth defects including vision problems, mental retardation, and hydrocephaly (water on the brain).
The chances of catching a zoonosis aren’t high.
With proper hygiene and a bit of education, there’s no reason for pet owners to worry about their furry, scaly, or feathered friends infecting them.
Here’s some advice.
Find the right pet for you and your family
Before buying or adopting an animal, make sure it’s appropriate for your home.
“There’s a right pet out there for everyone, but not all pets are right for all people,” Behravesh said. “Research, research, research. If you have children younger than 5, don’t bring a reptile or amphibian into the house — small turtles included. Even if the child never touches the pet because you keep it high up on a shelf, you may cross-contaminate the baby’s bottle from cleaning the cage, and your baby could get sick with salmonella.”
Get your pet to the vet
Regularly take your pet to the veterinarian for checkups and to ensure it’s healthy.
It’s hard to know if it could be infected with a zoonotic disease.
“Sometimes pets can carry germs, look perfectly healthy, and still make people sick,” Behravesh said.
And make sure your pet has been vaccinated for rabies.
“Vets have been routinely vaccinating dogs for rabies so we no longer see cases of canine-mediated rabies in humans,” Behravesh noted.
Wash your hands after contact with any animal
Always wash your hands after touching an animal and wash any other parts or articles of clothing that may have come in contact with it, too.
“A common way to get a zoonotic infection is from directly touching an infected animal,” Behravesh said. “Hugging, kissing, bringing it next to your face — these can increase your risk for certain germs.”
Be especially careful about cleaning up when you’re at petting zoos or fairs with farmyard animals that are made available for children to feed or touch.
“Make sure you and your children wash your hands, if not with soap and water, then with hygiene rubs and liquids,” Schaffner said. “If sinks or hygiene gels aren’t available, make sure you take the kids to the restroom immediately after.”
Handle feces with care
Animals can harbor infections in their fecal material, so be careful cleaning up after your pet.
Avoid touching poop when you pick it up and dispose of it.
Take care of it as quickly as possible, avoid touching your mouth, eyes, or nose, and wash your hands thoroughly immediately.
Avoid bites and scratches
Though it’s a seemingly obvious suggestion, try not to be scratched or bitten by your — or any — animals.
“Cat’s teeth, for one, are very thin and can puncture skin, and animals have a lot of bacteria in their mouths,” Hawkinson said. “If your skin is broken, it creates an environment for an infection to grow.”
If you do get bit or scratched by someone else’s pet, ask for the pet’s rabies vaccination status to ensure you haven’t been infected, then clean the affected area immediately with soap and water and apply antibiotic ointment.
“If you do get sick from a bite or scratch, let your doctor know, even if it’s weeks later,” Behravesh said.
Clean up after you clean up after your pet
When cleaning your pet’s habitat (carrier, crate, terrarium, etc.), do it outside with a water hose or in a tub, bleaching the tub afterward.
Don’t clean pet items in the kitchen sink or you risk cross-contamination.