Smithsonian.com

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Ask any emerging infectious disease expert: Human interaction with wild animals is never a good idea. Viruses are mutating and evolving all the time, and it only takes one such mutation – and the unfortunate alliance of circumstance – for a novel pathogen to make the leap from animal to human.

Bird flu may be approaching one of these transitions. New research published in mBio reveals that the flu virus has mutated into a novel strain of influenza, which gained the ability to transfer not just from bird to seal, but from seal to seal. Off the coast of New England, 162 seals have already succumbed to the new malady.  Researchers found that 37 mutations separate the new seal virus from its its ancestral avian strain.

While bird flu viruses sometimes infect mammals, they rarely gain the ability to jump from mammal to mammal directly (all known human flu viruses first evolved from those found in birds). Scientists have been studying this process in controversial experiments with H5N1 in ferrets, Carl Zimmer points out in a New York Times piece, but now nature has provided a real life example. Because seals are mammals like us – meaning they’re closer relatives than birds – it may be a small leap for the new virus to mutate into a version that can spread from seal to human, and then from human to human.

Scientists will continue to monitor the new virus, which they determined originally came from ducks before it made the transition to seals. They point out, however, that similar viruses that made their way to dogs and horses in the past never acquired the necessary mutations to infect humans.

While a pandemic is likely not in the books for this coming flu season, the researchers will bolster their efforts to follow what becomes of the New England seals and their worrisome new pathogen.

More from Smithsonian.com:

How to Give a Ferret a Deadly Flu

Swine Flu: Worst Case Scenario