Updated

Exotic animals captured in the wild are streaming across the U.S. border by the millions with little or no screening for disease, leaving Americans vulnerable to a virulent outbreak that could rival a terrorist act.

Demand for such wildlife is booming as parents try to get their kids the latest pets fancied by Hollywood stars and zoos and research scientists seek to fill their cages.

More than 650 million critters — from kangaroos and kinkajous to iguanas and tropical fish — were imported legally into the United States in the past three years, according to U.S. Fish and Wildlife Service documents obtained by The Associated Press under the Freedom of Information Act.

That's more than two for every American.

Countless more pets — along with animal parts and meats — are smuggled across the borders as part of a $10 billion-a-year international black market, second only to illegal drugs.

Most wildlife arrive in the United States with no quarantine and minimal screening for disease. The government employs just 120 full-time inspectors to record and inspect arriving wildlife. There is no requirement they be trained to detect diseases.

"A wild animal will be in the bush, and in less than a week it's in a little girl's bedroom," said Darin Carroll, a disease hunter with the U.S. Centers for Disease Control and Prevention.

While exotic pets from Africa, Asia and South America can be cute and fashionable, scientists fear that bacteria and viruses they carry can jump to humans and native animals. Recent statistics raise the alarm.

FROM EXOTIC ANIMALS TO HUMANS:

Zoonotic diseases — those that jump to humans — account for three quarters of all emerging infectious threats, the CDC says. Five of the six diseases the agency regards as top threats to national security are zoonotic, and the CDC recently opened a center to better prepare and monitor such diseases.

The Journal of Internal Medicine this month estimated that 50 million people worldwide have been infected with zoonotic diseases since 2000 and as many as 78,000 have died.

U.S. experts don't have complete totals for Americans, but partial numbers paint a serious picture:

--Hantavirus, which is carried by rodents and can cause acute respiratory problems or death, has sickened at least 317 Americans and killed at least 93 since 1996.

--More than 600 people have been sickened since 2000 with tularemia, a virulent disease that can be contracted from rabbits, hamsters and other rodents. At least three people have died.

--Three transplant patients in New England died last year after receiving organs from a human donor who had been infected with the lymphocytic choriomeningitis virus from a pet hamster. There have been 34 U.S. cases since 1993.

--More than 210,000 Americans were sickened between 2000 and 2004 with salmonella, and at least 89 died. Most infections come from contaminated food — but up to 5 percent have been linked to pets, especially such reptiles as iguanas and turtles. And last year, at least 30 people in 10 states were sickened with a drug-resistant form linked to hamsters and other rodent "pocket pets."

Some of the scariest diseases to emerge since 2001 also have been tied to exotic animals: One of the first times the deadly Asian bird flu reached the West was in eagles smuggled aboard a plane to Europe. Likewise, severe acute respiratory syndrome, or SARS, is believed to have jumped to people from caged civet cats in a Chinese market. The cats are believed to have gotten the virus from bats.

PARIS HILTON'S BITE, OTHER RECENT THREATS:

Carroll, the disease hunter, knows the dangers well. For the past three years, he has traveled the globe tracing the origins of a monkeypox outbreak in 2003 that sickened dozens of adults and children in the U.S. Midwest.

That disease, related to smallpox, is believed to have spread to people from rodents imported from Africa as pets. While no victims died, scientists are eager to understand the disease so they can stop a future outbreak.

Another newly discovered threat involves a current rage among exotic pet owners: a small carnivorous mammal with sharp teeth called a kinkajou. The nocturnal, tree-dwelling animals originally from Central and South America's rain forests have a dangerous bite — as Paris Hilton recently learned.

The actress used to carry her pet kinkajou named "Baby Luv" on her shoulder as she partied. This summer, Hilton landed in an emergency room when Baby Luv bit her on the arm.

The concern about a bite is real.

In 2005, a kinkajou bit a zookeeper in England on the wrist. The keeper's hand became infected, and she almost lost her fingers, said Dr. Paul Lawson, a University of Oklahoma microbiologist who first identified a new bacterium specific to kinkajous.

The first antibiotics doctors prescribed didn't work, so a combination of several was used to stop the aggressive infection.

Scientists worry that most Americans are ignorant of the threats, and the government's defenses are limited.

THE SCOPE OF THE PROBLEM:

Though such diseases can spread to humans in many ways, the exotic pet trade is a growing concern because of its lack of government oversight and its reliance on animals caught in the wild.

The legal wildlife trade in the United States has more than doubled in the past 15 years, the Fish and Wildlife Service said.

Last year alone, there were more than 210 million animals imported to the United States for zoos, exhibitions, food, research, game ranches and pets. The imports included 203 million fish, 5.1 million amphibians, nearly 1.3 million reptiles, 259,000 birds and 87,991 mammals.

Imported mammals caught in the wild range from macaque monkeys and chinchillas to wallabies and kangaroos.

Only wild birds, primates and some cud-chewing wild animals are required to be quarantined upon arriving in the United States. The rest slip through with no disease screening, except for occasional Agriculture Department checks for ticks.

"Taking an animal from the wild and putting it in your child's bedroom is just not a good idea," said Paul Arguin, a CDC expert on exotic animal imports. "We just don't know a lot about the diseases these animals carry."

THE POTENTIAL DISEASES:

The known diseases that can jump from exotic pets to humans are many:

Rodents can carry hantavirus as well as Bolivian hemorrhagic fever, which causes high fever, muscle pain and severe bleeding in humans and can lead to death.

Quarantines in 1989 and 1990 helped lead to the discovery of a new strain of the hemorrhagic disease Ebola in some primates. The primates either died or were killed.

Then there are the mystery diseases, which scientists have yet to understand.

During the 1990s, desert jumping rodents called jerboas were imported to Texas from Egypt as pets, according to Alan Green, a wildlife expert. Many new owners fell ill with a strange rash that defied treatment.

LOOPHOLES IN SCREENING OF LEGAL PETS:

Loopholes abound with legal imports, even when screening and quarantine occurs.

For instance, the thousands of monkeys that are imported each year for research from countries like China, Indonesia and Vietnam are quarantined for at least 31 days. While the monkeys are checked for tuberculosis, they aren't tested for other diseases unless they show signs of sickness.

However, monkeys can carry dangerous viruses and bacteria that don't make them sick but can harm people. For example, herpes B virus is a pathogen carried by 80 to 90 percent of adult macaques. The virus may not harm the macaques, but humans can be infected and suffer severe neurological damage or death.

In 1997, a 22-year-old researcher at Emory University's Yerkes National Primate Research Center in Atlanta died from herpes B virus weeks after a caged monkey splashed something in her eye.

Though the CDC has prohibited importation of most monkeys as pets since 1975, some macaques imported for research are now being sold on the open market.

"Whatever researchers are using and importing in great numbers is what we see in the pet trade," said April Truitt of the Primate Rescue Center in Nicholas, Ky.

The government acknowledges it doesn't track where animals go after quarantine.

THE CHALLENGE POSED BY ILLEGAL SMUGGLING:

Illegal trade presents another challenge. "If you can think of it, you can get it," said Mira Leslie, a disease expert in Washington state.

Smugglers have been known to tape small tubes filled with birds on their legs to smuggle them through airports or to cut deep boxes into car seats filled with exotic wildlife to drive across the Mexican border.

Inspectors have been on heightened alert looking for smuggled birds since a man in 2004 smuggled two Crested Hawk-Eagles on a flight from Bangkok, Thailand, to Brussels, Belgium. He had wrapped them in white cloth and stuffed them into handmade, wicker tubes that he carried in a handbag.

Officials later learned that a well-known bird collector ordered the eagles for thousands of dollars. When the birds were tested, they were found to be infected with a strain of the H5N1 bird flu virus. Fortunately, no human was infected.

A BUREAUCRATIC MESS:

America's defenses are a bureaucratic nightmare. Laws are outdated and no single agency is responsible for pre-empting the next outbreak.

--The CDC is in charge of human health and the quarantine of imported monkeys.

--The Agriculture Department has primary responsibility for livestock health and the quarantining of wild bird imports and wild cud-chewing animals.

--The Fish and Wildlife Service is charged with stopping smuggled wildlife and enforcing laws that protect exotic and endangered species.

"The three agencies don't work together," said Cathy Johnson-Delaney, a veterinarian who advised the Agriculture Department during the early 1990s. "We should be screening all critters coming into the U.S. We aren't doing this."

The CDC's Arguin acknowledges oversight of wildlife imports is reactive at best, noting that civet cats were banned from sale only after the SARS outbreak and the increased screening of birds occurred only after H5N1 started sweeping through Asia.

NO AGREEMENT ON FUTURE SOLUTIONS:

Jasen Shaw, president of U.S. Global Exotics, one of the largest American wildlife dealers, opposes banning exotic animal imports but acknowledges, "It doesn't do the industry any good to have diseases slip through."

Quarantine for all mammal imports — which are more likely to carry diseases that jump to humans — could be a solution.

Shaw said, however, that the industry would be wary of regulations that were too restrictive. Mass quarantining would be very expensive, he added.

Marshall Meyers, of the Pet Industry Joint Advisory Council, which represents the $30-billion-a-year pet industry, advocates a risk-based system. Disease threats posed to humans by other mammals is far greater than those posed by fish, he explained, so tighter regulation on certain species might be warranted.

The CDC convened a meeting this spring to examine the lack of oversight, exploring options but making no recommendations. With no government action imminent, some support a private solution.

"We should shift the burden to importers to prove that the animal imports are safe," said William Karesh, a zoonotic disease expert who works with the Wildlife Conservation Society. He suggests exotic importers take out insurance to foot the bill if their animals cause an outbreak.

"Why should you and I bear the cost of an outbreak when the industry makes all the money off this trade?"