These areas are home to many salamanders from the Plethodontidae and Salamandridae families, which are particularly vulnerable to Bsal infection, the researchers report. North American newts, which are in the Salamandridae family, have a 100 percent mortality rate when infected with Bsal in lab tests, researchers reported in 2013 in the journal Proceedings of the National Academies of Science. [Alien Invaders: Destructive Invasive Species]
The top U.S. ports for live salamander imports are alarmingly close to several of these hot spots, and 99 percent of the salamanders these ports trade hail from Asia, home to the chytrid fungus. Between 2010 and 2014, the researchers found, 768,572 salamanders potentially carrying Bsal arrived in U.S. ports. The top points of entry were Los Angeles; Tampa, Florida; New York; Atlanta; and San Francisco. (There were 779,002 salamanders imported in total during that time, with slightly more than 10,000 not carrying a risk of Bsal.)
"Atlanta and San Francisco really stood out as being in highly vulnerable zones," Vredenburg said.
Predicting exactly how and where Bsal might hit is a difficult task, warned Karen Lips, a biologist at the University of Maryland who has been involved in efforts to stop the fungus, but who did not take part in the current report. Vredenburg and his colleagues have made a good approximation, Lips told Live Science, but basic information about Bsal remains scarce.
"We don't know all the species that this thing can infect. That's one of the big problems," Lips said. "We also really don't know the details of the temperature requirements [for the fungus' spread], and we have no idea how the biology of the animals and the temperature and moisture requirements all interact." [7 Devastating Infectious Diseases]
Vredenburg and his colleagues are calling for the U.S. Fish and Wildlife Service (USFWS) to immediately ban live salamander imports. The agency is very concerned about the potential spread of Bsal, USFWS spokesman Laury Marshall Parramore told Live Science. However, the Lacey Act, which allows for the agency to forbid the importation and interstate transport of injurious species, does not have a provision for emergency listings, Parramore said.
"We are working with colleagues from federal and state government agencies, academic institutions, industry, and nongovernmental organizations to find innovative solutions to the problem," she said.
The Lacey Act is a century old and applies only to vertebrate animals, Lips said. It wasn't built to contain fungi, parasites or even invertebrates like invasive worms. Lips is part of efforts to get new laws on the books that would allow for better control and testing for disease in imported wildlife.
"Having gone through the Bd story, we know this is something that we need to be concerned about," Lips said. "We need to take this seriously, and we need to do everything we can now to prevent its introduction."
Vredenburg recommends that concerned citizens avoid buying Asian salamanders and urge their representatives to take action to regulate the foreign pet trade. People with amphibious (or reptilian) pets should never release them into the wild, he added.
"When people think they're releasing these animals into a nice little home somewhere, what they don't realize is they're also releasing all the pathogens and symbiotes that go with them," he said.
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