After more than 160 dead or dying seals washed up along the New England coast last year, scientists were left scratching their heads as to the cause.
But on Tuesday, scientists announced the culprit has been definitively pinpointed: a new strain of avian flu that has made the jump from birds to mammals. Researchers added the virus could be potentially harmful to humans.
According to CNN, the dead harbor seals began washing up along the coast from Maine to Massachusetts in September 2011. Throughout the next four months, at least 162 dead or moribund seals were recovered. They were mostly pups under the age of 6 months and most had suffered from severe pneumonia and skin lesions.
Initial pathogen screening pointed at a new strain of the H3N8 avian flu virus, which has now been dubbed 'seal H3N8.'
A pressing question, however, remained: How did this virus make the leap from birds to seals?
Scientists have since learned the mutant virus has developed the ability to attack mammalian respiratory tracts, according to a press release from Columbia University. They added that the virus may have also developed "enhanced virulence and transmission in mammals."
Researchers have thus warned that humans may soon also be at risk, NBC News reports.
This, of course, would not be the first time that a strain of influenza has spread between species.
"HIV/AIDS, SARS, West Nile, Nipah and influenza are all examples of emerging infectious diseases that originated in animals," W. Ian Lipkin, director of the Center for Infection and Immunity at Columbia University, told CNN.
Avian flu, in particular, has spread to humans before. The most notable of these have been H1N1 and H5N1. In 2009, the H1N1 flu pandemic -- more commonly referred to as "swine flu" -- caused more than 14,000 deaths worldwide.
"Any outbreak of disease in domestic animals or wildlife, while an immediate threat to wildlife conservation, must also be considered potentially hazardous to humans," said Lipkin.
The research has been published in the online journal of the American Society for Microbiology, mBio.