Jan. 7, 2010 — Pet African dwarf frogs from a single California breeder caused an 8-month salmonella outbreak in 31 states.
The outbreak extended from California to Massachusetts. Of the 85 cases, mostly in children, 16 were hospitalized, the CDC reports in its weekly MMWR publication. No deaths were reported.
Although reptiles — turtles in particular — have been responsible for previous nationwide salmonella outbreaks, this is the first known multistate outbreak spread by amphibians.
In this case, the amphibians were African dwarf frogs. The tiny creatures are less than 2 inches long from tip to tail. They live in water and are sold as aquarium pets.
The frogs are hard to handle — they tend to rest at the bottom of aquariums — so most of the infections likely came from contact with the water in which the frogs swam. Nearly a third of contaminated households cleaned the frog aquariums in the kitchen sink, “posing a risk for cross contamination with food preparation areas,” the CDC notes.
Infections in Utah and Colorado came from frogs given away as carnival prizes. An infection in New Mexico came from a frog purchased in a pet store; one in Ohio came from a department store.
Many of those infected didn’t know frogs or other amphibians could carry salmonella. Many patients’ parents had bought their kids frogs in order to avoid salmonella-carrying turtles.
It took the CDC a long time to figure out that frogs were the source of the outbreak, as cheese-flavored crackers consumed by several early patients led disease detectives on a wild goose chase. Eventually, the frogs were traced to a single California breeder. DNA tests showed that salmonella in water tanks and gravel from frog habitats was the same strain that caused the outbreak.
The CDC notes that there’s no law against selling small frogs. To prevent infections, the CDC advises pet owners to wash their hands thoroughly after touching animals or cleaning aquariums.