All influenza in humans comes from birds, prompting at least one controversial study in which researchers sought to answer how many influenza mutations occur before they become applicable to humans. Researchers finally published their results on airborne influenza viruses on ferrets, but the scientific community has put a moratorium on any further publication of research.

As the New York Times sardonically quips, nature does not subscribe to moratoriums. Starting in September 2011, hundreds of seals, usually babies under six months old, washed up on New England shores. Scientists have identified their cause of death as being a form of a deadly influenza virus mutated from an avian virus, and are concerned about what the virus means for mutations in humans.

In late 2011, seals were discovered as having pneumonia and skin lesions off the coast of Maine to Massachusetts. A total of 162 seal corpses were found over the course of the following three months. The scientists, who come from a diverse group of institutions including Columbia University and the Center for Infection and Immunity (CII), studied a subset of the seals that had passed away. They used diagnostic tools developed at the CII, and found that the seals had died of an H3N8 virus. The seals had contracted a virus that had been circulating in the North American avian population since 2002.

The virus attaches itself to receptors that are commonly found in mammals' respiratory tract. Scientists also suspect that the viruses have mutated to be more easily transmissible between mammals and are concerned that they may be airborne. The experts worry that the disease could cause a threat to public health, as many fear that current health infrastructure would be ill-equipped to handle a deadly pandemic in humans.

Scientists unaffiliated with the study are praising researchers on their comprehensive and quick identification of the source of the New England seal community's demise.

The researchers' next question is how the virus spread from birds to seals. While seals are carnivores, their prey mostly consists of fish and other seafood. Scientists had not suspected that avian influenza viruses would infect seals, prompting them to worry that such diseases could crop up in unexpected ways.

The study was published in the journal mBio.

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