Social, fun-seeking, comedic, and sometimes feisty, sea otters are endearing because they’re a lot like us. Scientists now know that we have something else in common with sea otters: Both of us can get the flu.
During an August 2011 sea otter health monitoring project, scientists with the U.S. Geological Survey and Centers for Disease Control and Prevention found that northern sea otters living off the coast of Washington state were exposed to the same flu virus that caused the 2009 world-wide pandemic in people. The exact date and source of exposure could not be determined, but the findings suggest that human flu can infect sea otters.
“Our study shows sea otters to be a newly identified animal host of influenza viruses,” said USGS scientist Hon Ip.
Otters are valuable beyond their child-like charisma:
However, sea otters are also imperiled. These marine mammals were nearly killed off due to intensive fur harvesting in the 18th and 19th centuries. Today, two wild sea otter populations in the U.S. are federally listed as threatened, which makes otter diseases — including flu — all the more dire.
The 2009 Pandemic
If you or someone you know got sick from the 2009 H1N1 influenza virus, commonly called “swine flu,” you weren’t alone. That year, the World Health Organization declared the infection a pandemic. The CDC estimates that between 43 million and 89 million human cases of the H1N1 infection occurred in the United States between April 2009 and April 2010, causing up to 18,300 related deaths.
The H1N1 virus has spread globally among people since 2009 and was the predominant flu virus in circulation during the 2013-2014 flu season.
The Otter Victims
The USGS and CDC researchers discovered antibodies for the 2009 H1N1 flu virus in blood samples from 70 percent of the sea otters studied during a 2011 otter health monitoring project. None of the otters were visibly sick, but the presence of antibodies means that they were previously exposed to influenza.
Further tests concluded that the antibodies were specific to the pandemic 2009 H1N1 flu virus, and not from exposure to other human or avian H1N1 viruses.
So, how did these animals get sick?
Scientists aren’t sure.
“This population of sea otters lives in a relatively remote environment and rarely comes into contact with humans,” said CDC scientist Zhunan Li.
An unrelated 2010 study showed that northern elephant seals sampled off the central California coast had also been infected with the 2009 pandemic H1N1 virus. This elephant seal exposure is the only other known pandemic H1N1 influenza infection in marine mammals, and similar to sea otters, it is unclear how the seals were exposed.
The new study is the first time that evidence of influenza infection has been detected in sea otters, although these viruses have previously been found in many other animals, including ducks, chickens, pigs, whales, and the seals.
“Our report identifies sea otters as another marine mammal species that is susceptible to influenza viruses and highlights the complex interspecies transmission of flu viruses in the marine environment,” said USGS scientist LeAnn White.
California Sea Otter Stranding Network: http://www.werc.usgs.gov/ProjectSubWebPage.aspx?SubWebPageID=5&ProjectID=232