Sea otter and seals in the Pacific Ocean, off the coast of Alaska, are infected with a virus that is only once seen in Atlantic animals.
A new study suggests that melting ice in the Arctic may be to blame – and climate change may help spread disease in new areas and in new animals.
Tracey Goldstein, a biologist at the University of California, Davis, found it strange when Pacific sea otters tested positive for phocine distemper virus – a cousin of canine distemper virus – when 2004, two years after a major outbreak on European harbor seals.
Genetic analysis showed that infections in both groups were connected. Dr. thought Goldstein how a virus usually goes into direct contact with a sick animal has managed to get from one northern ocean to another.
Until 2002, seas around the Arctic Circle remained largely frozen even in late summer. That year, however, the Arctic Ocean between the North Atlantic and the Pacific passed by the end of summer, he and his colleagues found.
Although sea otters do not venture far from home, seals may be thought to have the virus from the Atlantic to the Pacific, Dr. Goldstein.
Melting sea ice is a good explanation for the spread of viruses – but not just one, said Charles Innis, a veterinarian and director of animal health at the New England Aquarium in Boston.
"A skeptic can make arguments that maybe this virus can be transmitted through a host mediator, such as a bird that can fly remotely," said Dr. Disgusted, not involved in the new study. "Or maybe it's sent to the ballast water of ships or something like that."
Even illegal pet or livestock trading, or tight meat being shipped from one coast to another, can spread a virus, he added.
Dr. Goldstein and his team also look at antibodies to the virus in animals. There was no evidence of antibodies in trials conducted before the year 2000.
In 2002, though, new studies found "quite a difference" in antibody levels in Steller sea lions, he said. Dr. Goldstein, suggesting that animals have an active infection or recover from them.
The Phocine distemper virus is relatively lethal to sea seals in the Atlantic. Hundreds of harbor seals and gray seals were found dead in 2018 along the coast of New England, from Massachusetts to Maine, due to flu and flu infections.
But pet seals seem to be better able to survive the phocine distemper, Dr. Goldstein, and may serve as its reservoir – the ecological niche in which infection continues. Prevention may begin when a sick harp seal comes in contact with a gray seal .
The explosions seemed to come in cycles, Dr. Goldstein, because animals build immunity to infection. Every five to 10 years, as new seals and otters are born and general immunity is avoided, the population becomes more susceptible and another outbreak occurs.
The new study identified a second wave of antibodies that went viral in 2009 on many seal species, including ice seals, northern fur seals and Steller sea lions. The current study was completed in 2016, so it's not clear if the virus has spread since then, Dr. Goldstein.
But he was worried that another round of infection might not be far off. "Ice channels seem to be open year after year, so these rare events can become more common," he said.