Pet frogs associated with a nationwide outbreak of salmonella poisoning are up for sale again in the U.S., and officials at the Centers for Disease Control and Prevention are peeved.

According to the agency, 241 people from 42 states had been infected with the Salmonella Typhimurium bacteria responsible for the outbreak since July 18, CBS News reported. The infections have been linked back to African dwarf frogs and the fish tanks they live in.

A California company, Blue Lobster, ceased the frog shipments in April, but resumed shipping in early June from its Madera County, California, breeding facility, the agency said. And now the frogs are showing up in pet stores, toy stores, fairs and carnivals, and from online retailers.

Those particularly vulnerable to serious infections are kids under the age of five. Others at risk include pregnant women, people with weak immune systems, organ transplant recipients, and those undergoing chemotherapy.

Thirty percent of people sickened by the bacteria hospitalized, but no deaths have been reported.