The notorious swine flu that emerged in the U.S. in the spring of 2009 and made its way around the world in humans causing a public health emergency has been discovered in elephant seals off of central California, according to a new study published in the journal PLOS ONE.
While influenza can be transmitted between species and has been found in marine mammals before, researchers believe this is the first time a human pandemic strain has been found in marine mammals and how they got it remains an unsolved mystery.
Between 2009 and 2011, researchers from the University of California, Davis who had been studying flu viruses in wildlife tested swabs from more than 900 marine mammals from 10 different species off the Pacific Coast from Alaska to California and found the H1N1 virus in two seals who were 200 miles apart, while an additional 28 were found to have antibodies, according to a university press release.
“We thought we might find influenza viruses, which have been found before in marine mammals, but we did not expect to find pandemic H1N1,” said lead author Tracey Goldstein, an associate professor with the UC Davis One Health Institute and Wildlife Health Center. “This shows influenza viruses can move among species.”
The seals, who were satellite tagged and tracked, tested negative before going off on their annual spring trip to forage in the middle of nowhere off the continental shelf, but tested positive within days of their return. Goldstein told the San Jose Mercury News that when marine mammals get viruses, they assume it’s direct contact because no one knows how viruses survive in the ocean.
Researchers don’t believe human contact could be the cause in this case, but have suspicions that contact with seabirds or coming into contact with human waste dumped from ships may be responsible, according to the study.
Because the seals aren’t showing any signs of illness, the study raised concerns about marine mammals being carriers for human diseases and those who work around them are being advised to take precautions.
This research was conducted as part of the Centers of Excellence in Influenza Research and Surveillance program in order to offer a better understanding of emerging viruses in animals and people and how they’re transmitted.
“The study of influenza virus infections in unusual hosts, such as elephant seals, is likely to provide us with clues to understand the ability of influenza virus to jump from one host to another and initiate pandemics,” said Adolfo García-Sastre, professor of microbiology and director of the Global Health and Emerging Pathogens Institute at the Icahn School of Medicine.
After H1N1 killed nearly half a million people, the World Health Organization declared an end to the global pandemic in 2010 and now considers this virus to be a seasonal.
Photo credit: Thinkstock