Puppies carrying a common germ have infected 39 people and put nine of them into the hospital, federal health officials said Monday.

The cases are all linked to puppies sold in seven states by the pet store chain Petland, the Centers for Disease Control and Prevention said.

The infection, called Campylobacter, is common in dogs and it can pass to people easily.

“Regardless of where they are from, any puppies and dogs may carry Campylobacter germs,” the CDC said in a statement.

“The ill people are from seven states (Florida, Kansas, Missouri, Ohio, Pennsylvania, Tennessee and Wisconsin),” the CDC said. The illnesses go back nearly a year, to September of 2016.

“Evidence suggests that puppies sold through Petland are a likely source of this outbreak,” the CDC said. “Petland is cooperating with public health and animal health officials to address this outbreak.”

The CDC says Campylobacter is one of the most common causes of diarrheal illness in the United States, infecting 1.3 million people every year.

Dogs infected with Campylobacter might look perfectly well, but they can also have diarrhea, vomiting or a fever. In people, symptoms include diarrhea, sometimes bloody; fever; stomach cramps; nausea and vomiting.

Pregnant women, people over 65 and young children are most susceptible.

“Wash your hands thoroughly after touching dogs, their poop or their food. Take extra care that children playing with the puppies also wash their hands carefully,” the CDC advised.

“Pick up and dispose of dog poop, especially in areas where children might play.”

Most people with Campylobacter get better on their own but severe cases may be treated with antibiotics such as azithromycin or ciprofloxacin.