Millions of live animals enter the U.S. each year without disease screening—leaving us vulnerable to another outbreak, a former wildlife inspector says.
By Jonathan Kolby May 7, 2020 • 15 min readTwenty thousand live bullfrogs from China that will be cooked and eaten as frog legs. Forty green monkeys from St. Kitts and Nevis for biomedical research. Three hundred giant clams from Vietnam and 30 stingrays from the Brazilian Amazon for home aquariums.
That motley assortment is a miniscule glimpse of what the legal international wildlife trade might look like on a given day in any of the 41 ports of entry staffed by U.S. Fish and Wildlife Service inspectors. I routinely saw consignments like these—alongside crates filled with shampoo bottles, cucumbers, and freshly cut roses—at the Port of Newark, New Jersey, when I was a wildlife inspector, from 2004 to 2010.
At airports, seaports, and land border crossings in 2019, $4.3 billion of legal wildlife and wildlife products was imported into the U.S. Approximately 200 million live animals are imported to the U.S. annually, according to a five-year trade report: 175 million fish for the aquarium trade, and 25 million animals comprised of an array of mammals, amphibians, birds, insects, reptiles, spiders, and more. On top of that, thousands of illegally traded shipments of wildlife are intercepted each year. In 2019 alone, the agency opened more than 10,000 illegal wildlife trade investigations.
The diseases that hitchhike into the country on legally imported wildlife continue to go largely unnoticed.
But along with such a diversity of wildlife, a kaleidoscope of pathogens is also entering the country. My experience with the Fish and Wildlife Service, where I worked for 10 years, first as a wildlife inspector and most recently as a policy specialist regulating and managing the international wildlife trade, showed me that although many controls have been implemented to combat illegal trade, the diseases that simultaneously hitchhike into the country on legally imported wildlife continue to go largely unnoticed.
Importing any live animal brings with it the risk of disease—to native wildlife, to livestock, and to people. The outbreak of the novel coronavirus in China, theorized to have jumped from bats into humans and then spread at a wet market in Wuhan, possibly through an intermediate host, has shined a spotlight on how easily zoonotic diseases can emerge from wildlife. Indeed, an estimated 60 percent of known human diseases originated in animals, according to the World Organization for Animal Health.
Much of the public discussion around COVID-19 has focused on the potential role of the illegal wildlife trade in spreading pathogens. But as a wildlife trade specialist and conservation biologist—I studied the spread of disease among imported frogs—I’ve learned that we need to think just as critically about the risks and vulnerabilities presented by the massive legal trade, which continues to place both ourselves and the world at risk of more pandemics.
With few exceptions, the U.S. has no laws specifically requiring disease surveillance for wildlife entering the country, and the vast majority of wild animal imports are therefore not tested. Inspectors with the Fish and Wildlife Service are the first to set eyes on an imported shipment of animals, and they’re charged with enforcing a variety of national and international laws, regulations, and treaties that focus on preventing illegal and unsustainable trade. But its mandate doesn’t extend to monitoring animal or human health. Its only responsibilities related to disease are the enforcement of rules limiting trade in certain fish and salamander species, which have the potential to spread devastating disease to other animals of their kind.
In fact, no federal agency is tasked with the comprehensive screening and monitoring of imported wildlife for disease.
The Centers for Disease Control and Prevention (CDC) regulates the importation of wildlife and wildlife products known to “present a significant public health concern,” focusing primarily on bats, African rodents, and nonhuman primates, Jasmine Reed, a CDC spokesperson, wrote in an email. The U.S. Department of Agriculture (USDA) intervenes only if there’s a disease risk to poultry or livestock animals of agricultural importance.
This leaves millions of animals that come into the U.S legally each year unchecked for diseases that have the potential to spill over to humans or other animals.
The CDC insists it’s keeping an eye out. “CDC works closely with other federal agencies to ensure animals and animal products that present a public health concern are regulated,” Reed says. “Through our partnerships with international agencies, we are constantly evaluating and assessing what we and the international public health community do to detect, prevent, and control zoonotic disease threats.”
“I’m confident that our authorities are doing the best they can with the resources they have,” says Catherine Machalaba, a policy advisor for EcoHealth Alliance, a nonprofit focused on the connections between human and wildlife health. “But I’m not confident that’s a good enough benchmark when we’re talking about leaving the door open [to potential diseases that are] a threat to our health and security.”
The problem isn’t unique to the U.S.—most countries do not have a government agency that comprehensively screens wildlife imports for pathogens. “The absence of any formal entity dedicated to preventing the spread of diseases from the wildlife trade is such a chronic gap around the world,” Machalaba says. “When multiple agencies have to be called in for any given shipment, personnel is limited, and coordination is lacking, there’s bound to be gaps—a false sense of security that another agency has it covered.”
Many recent zoonotic outbreaks affecting people sprang from trade that was allowed at the time, says Lee Skerratt, a wildlife biosecurity fellow at the University of Melbourne, in Australia.
In 2003, for example, people in six U.S. states became ill from exposure to the monkeypox virus after it entered the country in a pet trade shipment of 800 rodents from Ghana. In that shipment, African giant pouched rats, rope squirrels, and dormice carried the virus. It spread to prairie dogs held in the same pet trade facility, which were then sold to the public, starting the animal-to-human outbreak. Luckily, although human-to-human transmission of monkeypox can occur, no cases were confirmed.
Three months after the infected animals had been imported, the CDC banned the import of all African rodents into the U.S. That gave the Fish and Wildlife Service the legal power to detain shipments in violation of the ban and alert the CDC, which could choose to require quarantine, re-exportation, or euthanization of the animals.
Although this outbreak led to an import ban on African rodents, the government stopped short of doing any risk assessments to consider whether rodents from other places might also carry diseases that would require regulation, Machalaba says.
“Wildlife coming into the U.S. are sourced from many countries that are ‘hot spots’ for emerging diseases—of potential concern for human health but also posing threats to other sectors via our food systems and ecosystems,” Malachaba says.
Officials have long known about the gaps in the U.S.’s regulatory system. In 2005, the National Academies of Science published a report that found a “significant gap in preventing and rapidly detecting emergent diseases” from imported wildlife.
Five years later, the U.S. Government Accountability Office, which audits government spending and operations, published a report on live animal imports and diseases. It found that the Fish and Wildlife Service “generally does not restrict the entry of imported wildlife that may pose disease risks.” Furthermore, the report says, the CDC doesn’t use its full power to prevent the import of live animals that pose a risk of zoonotic diseases.
The 2010 report recommended that the CDC, the Fish and Wildlife Service, and USDA develop and implement a coordinated strategy to prevent the import of animals that may be carrying diseases. But a follow-up assessment in 2015 found that the agencies did not take action. There simply weren’t the economic or staffing resources to make it happen, it says.
The ability to prevent and control emerging zoonotic diseases requires an understanding of the diversity and abundance of pathogens being imported. But without monitoring and surveillance of imported wildlife, we don’t have this information, Skerratt says. “This is a problem for the wildlife trade as there is much that we don’t know, especially for diseases that could affect other wildlife,” he says.
