Furry “pocket pets” such as hamsters, mice and rats have sickened up to 30 people in at least 10 states with dangerous multidrug-resistant bacteria, health officials are warning.

It is the first known outbreak of salmonella illness tied to such pets and reveals a previously unknown public health risk, officials said in a report released Thursday.

Many of the victims were children. Six were hospitalized for vomiting, fever and severe diarrhea. Some passed the illness to others. The germ they had was resistant to five drugs spanning several classes of antibiotics.

“This is likely an underrepresentation of how large the problem is” because others who were sick may not have gone to doctors, and not all labs do the kind of tests that would detect this germ, said Dr. Chris Braden, an epidemiologist at the Centers for Disease Control and Prevention.

Salmonella infections are common from reptiles, especially small turtles called red-eared sliders that are banned but have made an illegal comeback in several states in recent years. The 2003 monkeypox outbreak that originated in imported African rats and spread to U.S. prairie dogs showed the risks of owning exotic pets.

But cuddly little pocket pets such as hamsters were not thought to pose much of a problem.

Gerbils, guinea pigs, ferrets and rabbits also could carry the germ, the CDC said.