Nature & Environment

New Seal Flu could Pose a Threat to Human Health

Brooke Miller
First Posted: Jul 31, 2012 06:40 AM EDT

According to a new US research released Tuesday, a new kind of bird flu has cropped up that has been causing deadly pneumonia in baby seals off the northeastern US coast. And it could also pose a risk to humans. 

This new strain of influenza virus is named avian H3N8 and was the prime reason behind nearly 162 seal deaths along the US coastline last year.

This study in mBio was published in the journal of the American Society for Microbiology. The H3N8 virus initially started life as a bird flu but jumped species. And now US scientists are trying to find out how it spreads in order to eradicate it completely. It was noticed that the dead seals were younger than six months of age.

"There is a concern that we have a new mammalian-transmissible virus to which humans haven't been exposed yet. It's a combination we haven't seen in disease before," said Anne Moscona of Weill Cornell Medical College in New York City, editor of the report.

The authors from Columbia University and the National Oceanic and Atmospheric Administration Outbreaks, say transmissible and pathogenic flu viruses in mammals, like the one in this study, clearly pose a concern for human health. In 2009, for instance, the H1N1 'swine flu' virus that emerged in humans apparently originated from a reassortment of flu viruses found in birds, pigs, and humans. The H3N8 strain in New England harbor seals may come to represent the first sighting of a new group of influenza viruses with the potential to persist and move between species.

Scientists have carefully viewed the full genome of the new strain and found it originated from a bird flu virus that had been circulating in North American waterfowl since 2002. Over this period of time the virus infected the mammals by attacking the receptors in their respirator tracts.

For the study, they analyzed the DNA of a virus associated with a die-off of 162 New England harbor seals in 2011. Autopsies of five of the seals revealed they apparently died from infection with a type of influenza called H3N8, which is closely related to a flu strain that has been circulating in North American birds since 2002. Unlike the strain in birds, this virus has adapted to living in mammals and has mutations that are known to make flu viruses more transmissible and cause more severe disease.

Based on the study, the scientists conclude that, this strain is a novel virus that infects mammals and may well pass from mammals and from animal to animal, a combination of traits that make it a potential threat to humans. Also the possibility that a bird flu virus would infect seals hadn't been widely considered before. 

"Flu could emerge from anywhere and our readiness has to be much better than we previously realised," said Dr Moscona. "We need to be very nimble in our ability to identify and understand the potential risks posed by new viruses emerging from unexpected sources.

It's important to realise that viruses can emerge through routes that we haven't considered. We need to be alert to those risks and ready to act on them."

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