Growing number of diseases jump from animals to humans

WASHINGTON -- The monkeypox outbreak illustrates a growing problem: Exotic animals give exotic diseases to people who get too close, a trend that some medical specialists call a serious public health threat.

Such diseases can become a threat not just to the people who buy and sell exotic pets, but to the general public if they spread to native animals and become established in the United States. Federal health officials are working frantically to ensure doesn't happen with monkeypox.

"This is a harbinger of things to come," warns Michael Osterholm of the University of Minnesota, who advises the government on infectious disease -- and has long warned that there's too little oversight of the health threats of imported animals.

"There are some of us who feel like lone voices in the night" in calling for better scrutiny, adds Peter Jahrling, a scientist at the U.S. Army Medical Research Institute. "Perhaps incidents like this might bring some much-needed re-examinations."

Monkeypox, a relative of smallpox usually found in tropical African forests, apparently jumped from an imported Gambian giant rat into prairie dogs when both species were being housed together by an exotic pet distributor in Illinois.

Health officials are investigating nearly three dozen possible cases of monkeypox in people who bought or cared for the prairie dogs, in Wisconsin, Indiana and Illinois. The outbreak marks the first time monkeypox has been detected in the Western hemisphere.

Nor is it the only threat, say critics who fear a growing trend.

SARS, the respiratory epidemic, is thought to have come from civet cats bred as an exotic meat in Chinese markets where bats, snakes, badgers and other animals live in side-by-side cages until they become someone's dinner.

Japan recently banned the importation of prairie dogs because they can carry plague. The rodents had been wildly popular as pets in that country.

Just last summer, a group of prairie dogs caught in South Dakota was discovered to have another dangerous infection, tularemia -- noticed only after the animals were shipped to 10 other states and five other countries. While the Centers for Disease Control and Prevention never recorded any human illnesses, it advised adults who handled the ill rodents to take precautionary antibiotics.

Then there's salmonella, which iguanas and other reptiles, as well as birds, routinely shed in their feces. The CDC counts a stunning 90,000 people a year believed to have caught salmonella from some form of contact with a reptile, either touching it or touching a surface where the reptile had tracked the bacteria.

A common scenario, Osterholm says: Parents wash the reptile cage in a bathtub or sink their child uses, and the child gets sick. Salmonella can be life-threatening in children.

Worse is if a disease jumps from exotic pets into native wildlife -- a threat whenever owners dump an animal that gets too large or tiresome to care for.

CDC's Dr. Steve Ostroff made a plea Monday for prairie-dog owners not to release their animals into the wild, but to call a veterinarian or their state health department for proper care information. Call ahead before taking a sick prairie dog to a veterinary clinic to guard against possible exposure of other animals to monkeypox, he said.

Already, a sick prairie dog has infected a rabbit who lived in the same house; Jahrling worries that hamsters and gerbils could be incubating monkeypox from pet-store transmission; in Africa, squirrels carry the virus.

"Even if we do manage to bring the prairie dog problem under control, ... it's very important that we keep our guard up" by watching for monkeypox in other species, Ostroff said Monday.

There are no good counts of how many exotic animals are sold, but they're immensely popular, says Richard Farinato, director of the Humane Society of America's captive wildlife program. Some 800,000 iguanas alone are imported for the pet trade.

There is little federal scrutiny of most imported animals for potential human health risk, and rules on owning and selling exotic animals vary by state and city.

"We have a policy that says don't buy these kinds of animals as pets. This (monkeypox) is one example of why," Farinato says.

But even the critics aren't immune to the lure of exotic pets. Osterholm several years ago let his teenage son buy an African dwarf hedgehog, another pet fad -- on condition that it be tested for disease. Osterholm's laboratory found the animal harbored three strains of salmonella never before seen in Minnesota.

They kept the hedgehog, but "extreme hand washing took place," Osterholm recalls. "It wasn't that fun."

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EDITOR'S NOTE -- Lauran Neergaard covers health and medical issues for The Associated Press in Washington.