The outbreak of a rare strain of salmonella that sickened scores of people, including several infants, across the United States and Canada has been linked to pet bearded dragons, some most likely obtained from the same breeder in Southeast Asia, according to a study published by the Centers for Disease Control and Prevention.

The outbreak covered in the study occurred in 2021 and 2022, but salmonella infections associated with bearded dragons have become increasingly common in recent years, mirroring the rising popularity of the goofy, scaly lizards as household pets.

Last year, a salmonella outbreak in 20 states affected nearly three dozen people, 10 of whom were hospitalized, according to the CDC.

No deaths were reported.

Bearded dragons, scientifically known as Pogona, are native to Australia, but most of those sold to pet owners are bred in captivity. The banana-size lizards have won the hearts of pet enthusiasts across the world. Not only are they captivating to observe, but bearded dragons also can make engaging pets when provided with proper care.

Judging from the many social media accounts that document their adventures, pet bearded dragons spend a fair amount of time frolicking with their owners, wearing adorable outfits and scampering around living rooms and kitchens as if they were dogs.

“They are the golden retriever of the reptile world in terms of ease of handling,” said Dr. La’Toya Latney, president of the Association of Reptile and Amphibian Veterinarians and the owner of several pet reptiles. (Unlike dogs, however, bearded dragons are not easy to potty train.)

The association does not discourage hobbyists from handling their pet bearded dragons but cautions against allowing them to roam freely outside their tank. “It actually increases the possibility of them getting sick or hurt,” Latney said.

The study the CDC published this week once again highlights the risks associated with keeping reptiles and amphibians as pets, especially in households with young children. As with many animals, the digestive tracts of bearded dragons harbor salmonella bacteria, which are a natural part of their microbiome and cause the animals no evident harm.

The bacteria are shed in the lizard’s feces and can end up on the animal’s skin and just about anywhere the bearded dragon rambles. Problems can occur when humans handling the creatures do not properly wash their hands and inadvertently transmit the bacteria to their mouths.

“I have college students that will come to class with their bearded dragon on their shoulder, which is probably not the most hygienic thing,” said Brian Todd, a conservationist at the University of California, Davis, who specializes in reptiles and amphibians and was not involved with the study. “After you’ve handled one, you need to wash your hands, especially before preparing food or picking up your child.”

Bearded dragons aren’t the only source of reptilian-borne outbreaks. Last year, more than two dozen people in 11 states were sickened by salmonella linked to small turtles. That outbreak led to the hospitalization of nine people and prompted a warning from the CDC against allowing children younger than 5 to have turtles as pets.

(The sale of turtles less than 4 inches has been banned since 1975.)

The study published this week in the journal Emerging Infectious Diseases used genetic whole-genome sequencing to determine the origin of salmonella infections that sickened two infants in Ontario, Canada. Researchers determined that the illnesses were caused by salmonella vitkin, a rare strain that had not been detected in Canada or the United States before 2021.

Dr. Katherine Paphitis, an epidemiologist at Public Health Ontario who was the lead author on the study, said the discovery prompted health officials in both countries to join forces to determine its origins.

Paphitis said that there are 2,500 serotypes of salmonella but that only about 100 sicken people, and just a handful are responsible for a majority of human infections. Older people, infants and those with weakened immune systems are especially vulnerable to serious illness, she said.

Sequencing of the bacteria allowed researchers at Public Health Ontario to link the two infants who had been sickened. Each family, they discovered, had bearded dragons. With genetic fingerprints in hand, Canadian officials reached out to their CDC counterparts, who then identified a dozen cases of salmonella vitkin in the United States. Health officials in both countries warned pet shops and pet owners about the risks. “Don’t kiss or snuggle your bearded dragon,” the CDC said, “and don’t eat or drink around it.”

The response to the outbreak showcased collaboration between the health agencies, Paphitis said, and also helped spread vital information about bearded dragons that seemed to elude many owners.

“If you are letting them free roam,” she said, “maybe don’t let them onto your kitchen countertop.”

This article originally appeared in The New York Times.