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