A creature the size of a quarter that amuses children with comical poses has sparked a nationwide salmonella outbreak, depriving public health officials of sleep.

Over the past two years, federal officials have confirmed nearly 220 illnesses from Oregon to Massachusetts traced to African dwarf frogs. But those positive lab tests reflect just a shadow of the outbreak, said

"There are hundreds (of cases) that we know about which means we have thousands of people sick," he said.

The Centers for Disease Control and Prevention said the outbreak was traced to a single breeder in California. But federal officials have been helpless to do anything about it.

"What's frustrating is that we don't seem to have the tools to stop these sorts of outbreaks," Keene said. "If it's a food source, it's regulated. They recall the product. They shut down the facility. But there's never been any recall of (the frogs). The company hasn't even been publicly identified."

Frogs, like other amphibians and reptiles,

. Pet stores warn customers about the risk but people forget to wash their hands after touching the animals, cleaning their tanks or even coming into contact with the water. Children are especially at risk. Hundreds of thousands got sick in the 1960s from handling tiny turtles that were popular pets.

The ban didn't include frogs, however, leaving them in a regulatory vacuum. That's caused gnashing of teeth among public health officials like

, a veterinarian and outbreak specialist at the CDC.

"My job is to prevent illnesses," she said. "I have lost a bit of sleep over this outbreak."

African dwarf frogs are aquatic but surface to breathe air. Although low maintenance like goldfish, they're more entertaining.

"A lot of people keep them," said Nevin Bailey, co-owner of AquariumFish.net, which sells the frogs mainly through the Internet. "They'll swim, swim, swim to the surface for air and then go down and strike these frozen poses. They look like statues. They'll be on their tiptoes, like a ballerina, and have one arm up and one arm down. They have really strange behavior."

Children love them, as the outbreak shows. About 70 percent of those sickened have been kids younger than 10. Babies have been poisoned, and 30 percent of all the patients have been hospitalized. The number of cases on the West Coast ranges from five in Oregon to 22 in Washington.

Although the CDC has not named the breeder, California public health confirmed that the outbreak was traced to Blue Lobster Farms in Madera, Calif.

In December 2009, after the CDC identified African dwarf frogs as the cause of the outbreak, the agency asked the

to visit Blue Lobster Farms, the main supplier in the United States. Jill Yaeger, director of environmental health for the county, said her office collected water and other samples. Salmonella turned up in tanks, water, floor drain and brushes.

"The facility had fairly widespread contamination," said Dr. Debra Gilliss, head of disease investigation with California Public Health.

Last April, the CDC had a conference call with the company's owner, Stuart Weil, urging him to monitor bacterial levels, establish sanitary controls and consult a hydro engineer. Yaeger said he'd been using ultraviolet treatment to kill bacteria in some tanks, showing lower levels of contamination. So Weil expanded the UV lights throughout his facility and consulted various experts.

He kept selling his frogs, and the outbreak drifted below the public health radar as officials turned to other investigations.

But people kept getting sick.

Last month, after an infant in a home in New York with African dwarf frogs fell ill, the CDC called the Madera County Health Department, sending Yaeger back to Blue Lobster Farms for tests.

On Tuesday, under pressure from public health authorities, Weil suspended shipments.

"We are very pleased he voluntarily agreed to stop selling them," Gilliss said.

Weil could not be reached for contact: No one at Blue Lobster answered the phone.

Yaeger said the owner is concerned about the illnesses and intends to completely clean the facility. But getting rid of the salmonella could be difficult.

"I don't know how you clean an environment with a gazillion frogs in it," said Keene, a senior Oregon epidemiologist.

In the meantime, the CDC has contacted pet store chains, urging them to warn customers about the risks posed by African dwarf frogs. They're still widely available, however. In fact, Petco has a special right now, selling the frogs on the Internet at a 20 percent discount for $2.23 apiece.

Health officials would prefer they weren't on the market.

"The best thing is not have them as pets as all from a public health point of view." Keene said.