Worldwide weather patterns may influence influenza pandemics

By Laura Mize • Published: March 11th, 2015
Category: Health in a Heartbeat

What does the weather have to do with health crises? Perhaps more than you think, at least according to new research published in the Proceedings of the National Academy of Sciences. Researchers contend that cooler-than-normal ocean temperatures and changing bird migratory patterns may be a harbinger of a major global health crisis.

The article shows that the last four major human flu pandemics all followed the weather pattern called La Niña. This pattern occurs every few years, causing lower temps in the Pacific Ocean and generally cooler weather worldwide. The climate pattern also prompts many species of birds to mix up their normal migratory routes, bringing together varieties of the winged creatures that normally would not mingle.

This matters because wild birds are one of the main sources of flu viruses that infect humans. A massive bird gathering is the perfect opportunity for a cacophony of flu viruses to also intermix. That’s a recipe for creating a hybrid version of the virus that’s so unique and genetically diverse, humans have never seen it before.

The scientists write that changes in weather also may modify water sources in the areas where birds spend time. This could be a factor that increases bird contact with other species that may carry or become infected by influenza viruses.

For example, in the 2009 swine-flu epidemic, the researchers say birds may have contributed to the genetic mixing of various flu viruses in swine to create the deadly strain that infected so many.

The researchers say it’s worth considering whether La Niña is a key cause in some flu pandemics. Even a little bit of predictability for such outbreaks could be a major boon for public health.