Could La Niña weather pattern promote dangerous flu pandemics?

Kathleen Blanchard's picture
Could flu pandemic like H1N1 be spread by La Niña weather pattern?

Flu pandemics are unpredictable, but scientists have discovered the La Niña weather pattern might help promote new strains of flu that can become pandemic and even deadly.

Scientists Jeffrey Shaman of Columbia University's Mailman School of Public Health and Marc Lipsitch of the Harvard School of Public Health theorize La Niña changes the way birds migrate, which sets up a scenario for altering flu strains that can become more dangerous.

According to the authors, La Niña changes the migration, intermingling, fitness and stop over times of birds.

For this study the researchers noticed changes in ocean temperature that correlated with the last four flu pandemics, which also was consistent with the La Niña phase of the weather pattern.


"We know that pandemics arise from dramatic changes in the influenza genome. Our hypothesis is that La Niña sets the stage for these changes by reshuffling the mixing patterns of migratory birds, which are a major reservoir for influenza," says Jeffrey Shaman, PhD, Mailman School assistant professor of Environmental Health Sciences and co-author of the study.

The authors point out past studies in the study finding, published online in the journal PNAS that suggest the way birds migrate can lead to gene- swapping from the mixing of migratory birds, potentially creating variations of the flu that can become pandemic,

The authors also say the La Niña weather pattern could contribute to flu outbreaks because bird migration patterns change the way birds come in contact with animals like pigs. The 2009 H1N1 flu pandemic was the result of gene-swapping that occurred between birds and pigs.

The authors speculate the La Niña weather pattern could possibly predict flu pandemic, based on their finding that the last four influenza outbreaks were preceded by changes in weather in the Pacific region. The authors recommend more studies “using influenza population genetics, virus prevalence in various host species, and avian migration patterns.”

PNAS: doi:10.1073/pnas.1107485109
“The El Niño–Southern Oscillation (ENSO)–pandemic Influenza connection: Coincident or causal?”
Jeffrey Shaman, Marc Lipsitch
January 17, 2012