Every year millions of wild or exotic animals arrive in the United States to spend the rest of their lives living with families as pets.
Stowing away inside many of these creatures is an array of microscopic parasites, bacteria and viruses. Under the right circumstances, they can trigger disease among livestock and humans - such as this spring's monkeypox outbreak in the Midwest.
Standing guard against this threat at the nation's ports of entry are overworked inspectors such as Cathy Cockey of the U.S. Fish and Wildlife Service.
The 18-year veteran is one of two assigned to examine shipments of reptiles, fish and other animals at Baltimore-Washington International Airport and Washington Dulles International Airport. But if iguanas arriving from South America are infected by the potentially deadly salmonella bacteria, it's unlikely Cockey would know it. "We're not trained to detect diseases," she says.
Even if she does spot an ailing lizard, none of the nation's myriad regulations governing imported animals allows her to stop it. "As a law enforcement officer, I have to have a law to fall back on," she says. "As long as they're shipped humanely, unfortunately, it's not a shipment I can hold up."
The growing monkeypox outbreak in three Midwestern states this week has raised alarms among state and federal health authorities. It has also exposed a system of regulations that critics call too weak and fragmented to prevent the importation of human and wildlife diseases. At least 37 people have been infected with monkeypox after exposure to pet prairie dogs that may have been infected by a Gambian rat imported from Africa. The outbreak has prompted calls for federal action.
"The answer, we think, is for the federal government to say 'no' to more imports of [exotic pets] until we get the imports under control," said Richard H. Farinato, director of captive wildlife protection for the Humane Society of the United States. For the creatures' sake and public safety, he said, "no wild animal is a suitable pet, whether it is a native animal or an exotic animal."
The U.S. Centers for Disease Control and Prevention regulates the import of animals that can pose a disease risk for humans, including dogs, cats, turtles and primates.
"However, there are all kinds of exotic species that may be unknown vectors of human disease," said Tom DeMarcus, environmental health officer for the CDC's division of global migration and quarantine. The Gambian rat-prairie dog connection was not previously recognized as a source of infection.
DeMarcus said one or both of the animals may well be added to the agency's watch list.
Still, millions of Americans buy, breed and trade wild and exotic animals without getting sick or triggering a health crisis.
Candy King, a 45-year-old homemaker in Morehead City, N.C., wouldn't part with her four prairie dog pups. "They're cuddly, they bond with you, and they're very protective," she says. "They have been known to lunge at strangers to protect their family."
Others have not been so lucky. Repeated outbreaks of salmonella poisoning, particularly among small children, prompted the CDC to ban the import of small pet turtles in the 1970s.
Since 1975 it has been illegal to import primates for the pet trade because they can carry hemorrhagic fevers such as the deadly Ebola and Marburg viruses as well as yellow fever and monkeypox.
In 2000, imports of three species of African tortoises that had become popular pets were banned because they carried a tick that spreads heartwater disease - a deadly livestock illness.
Japan recently banned imports of popular prairie dogs because some were arriving with plague infections. And last year, pet prairie dogs shipped from South Dakota to 10 other states and five countries became ill with tularemia - a bacterium so infectious and deadly that it was once studied for use as a biological weapon.
America's defense against these illnesses is a maze of overlapping agencies and regulations laced with loopholes.
For example, imports of cats, dogs, turtles and primates as pets are regulated by the CDC because they can be sources of human disease. Imports of endangered species are monitored by the U.S. Fish and Wildlife Service, while animals that might introduce agricultural diseases are regulated by the U.S. Department of Agriculture.
Imported agricultural species such as horses, cattle and sheep are subject to quarantine and other regulation before they can enter the United States.
But there are no comparable safeguards against the import of diseased rodents such as Gambian rats, said Jim Rogers, a spokesman for the USDA.
"We also don't regulate importation of fish, reptiles, lions, tigers, bears, foxes, monkeys, endangered species, guinea pigs, hamsters, gerbils, mice, rats, chinchillas, squirrels, mongooses, chipmunks, ferrets and other rodents," he said.
There are some safeguards, however. Scientists importing rodents inoculated with diseases for study need a USDA permit, Rogers said. "Or, say the [exporting] country has an animal disease, like foot-and-mouth disease; if it's an animal that can carry that disease, it would fall under [USDA] restrictions."
Wholesale animal traders and those who sell exotic and wild animals as pets also need a USDA license. But that license requires only that they meet minimum standards for the animals' care and feeding.
"If we're going to regulate, there should be one organization, one agency responsible for it, and it should have a system that is standardized across the states," Farinato said.
Because the government's controls are so fragmented, little information is available on the scale of the wild and exotic pet trade. When the Humane Society asked the Fish and Wildlife Service for data on reptiles alone, it learned that 18.3 million were imported between 1989 and 1997 - an average of more than 2 million per year.
"Anytime you bring in a wild-caught animal, or collect wild animals in the U.S. for the pet trade, you are taking with that animal everything it has been exposed to into the country and into the home of whoever buys it," Farinato said.
"And with all these things, whether it is a newly discovered monkeypox virus, parrot fever, salmonella or some other parasite, there is no way to clean these animals out unless you go through a long period of quarantine and treatment."
Worse, Farinato said, the stress of capture and transport may lower the animals' resistance, allowing the organisms they harbor to blossom and escape to the environment, posing infection risks to animals and people.
Even so, Americans continue to seek out exotic and wild animals as pets, often following fads and fashions.
For example, Vietnamese potbellied pigs were hot several years ago, "until people discovered they didn't want livestock in their living room," Farinato said. "Right now, reptiles are a big boom item, as are primates."
Sugar gliders and marmosets - both small primates - are popular, as are macaws, cockatoos and prairie dogs.
The Humane Society estimates that there are 10,000 big cats - including lions and tigers - in private hands here. Tomorrow, Congress is scheduled to consider a bill that would ban the interstate sale of the animals as pets, Farinato said.
No one has done a scientific study to determine why people want to own such exotic species. For some, it appears to be the novelty. "They always say, 'I didn't want the typical pet,'" Farinato said.
Others enjoy the reaction. "They go to the malls with their iguana or boa [constrictor] on their shoulder or ride in the car with a monkey chained in the back," he said.