Melting Lakes May Release Dangerous Flu

14-Dec-2006

Is dangerous flu trapped in this ice?

Over 5 years ago, we warned that dangerous ancient microbes could be released when glaciers melt, due to global warming. Scientists now think that flu viruses that have been frozen in Siberian lakes for centuries could be released by birds, as the climate changes, causing the lakes to melt.
In New Scientist, Catherine Brahic quotes researcher Scott Rogers as saying, "Our hypothesis is that influenza can survive in ice over the winter and re-infect birds as they come back in spring." He thinks that frozen lakes act as "melting pots" for flu viruses, allowing viruses from one year to mix with those from earlier years.

He worked with researchers Dany Shoham and David Gilichinsky to obtain samples of ice from Siberian lakes where migratory birds stop. They looked for flu viruses in lakes that freeze and thaw every year and found a strain of flu virus that was around in the 1930s and then returned in the 1960s. I think that the virus may have been deposited in one of these lakes by birds. Other birds may have picked it up and redistributed it, years later, since the flu virus remained alive beneath the ice. They are studying ice cores from glaciers in Alaska, Wyoming and Canada, and they also plan to study cores from Siberia and the Himalayas. Many of the glaciers are on the flight paths of migratory birds.

Virologist Jonathan Stoye thinks that whether or not these viruses are infectious depends on how they were frozen. If they were frozen in the water, they are less likely to be reactivated than if they were originally frozen inside bird droppings, which then fell into the lakes.

The first ancient virus that was found frozen in ice was discovered in 1999 in the Arctic. Other researchers have found bacteria that survived for over 30,000 years in a frozen pond in Alaska.