Flu and climate may be connected

BBC : Global climate shifts and flu pandemics may be linked, say researchers. Weather can influence the migratory patterns of wild birds; thus different species are brought together that don’t normally mix. The birds then share viruses, which can morph into different strains to which the human population has not been previously exposed. In a paper published yesterday in the Proceedings of the National Academy of Sciences, Jeffrey Shaman of Columbia University and Marc Lipsitch of Harvard University note that the four most recent human influenza pandemics—in 1918, 1957, 1968, and 2009—were preceded by a climate pattern called La Niña. However, the researchers emphasize, most La Niñas have not preceded a pandemic. Rather, climate patterns could be one of several factors that affect the spread of viruses.