La Nina May Be Linked To Flu Pandemics

BBC:

La Nina is the cold cousin of El Nino - the two collectively making up the El Nino Southern Oscillation (ENSO).
"Certainly ENSO affects weather and precipitation and humidity around the world," said Jeffrey Shaman from Columbia University in New York.
"But the effects are very varied around the world - there's no coherent picture."
Nevertheless, the last four pandemics - the Spanish Flu that began in 1918, the Asian Flu of 1957, the Hong Kong Flu of 1958 and the swine flu of 2009 - were all preceded by periods of La Nina conditions.
What pandemics have in common is that they all feature novel strains of the virus to which people have not developed immunity.
Typically these are created when two existing strains infecting an animal such as a bird or a pig exchange genetic material.
The link to La Nina events is not clear. But recent research has shown that some wild birds' patterns of flights and stopovers during migrations, or moulting times, differ between El Nino and La Nina years.
"Our best guess is this brings together birds [in La Nina conditions] that don't otherwise mix, and that allows the genetic reassortment to take place," Professor Shaman told BBC News.
Yet the fact that many other La Nina periods have not been followed by a pandemic indicate that other factors must also be involved.

It's bad enough that we get wet springs and dry summers out of La Nina, I'd hate to think we might get killer flu in the bargain.  Again, my main concern is that we might start seeing stronger or longer La Nina's due to climate change.  I have no idea if that might be the case, but that would definitely be problematic for grain farming in the Midwest.  We don't need to throw in the possibility of pandemic also.