Fish research leads to flu discovery
As cold winter weather approaches, millions of people look for remedies to avoid the flu. Yet influenza outbreaks equally affect those living in warm, tropical regions where the seasons are less pronounced and flu outbreaks are less regular. This discrepancy between the seasonality of flu outbreaks in tropical and temperate climates has made it challenging to study the environmental factors that drive the flu.
In a new study, a team using an approach known as empirical dynamic modeling (EDM) found that a key environmental driver – absolute humidity – links flu outbreaks across the globe. The research was, in part, an unexpected result of a grant from the Lenfest Ocean Program to study a small, oily fish called Gulf menhaden using the same approach.
Ethan Deyle, postdoctoral researcher with the Scripps Institution of Oceanography at the University of California San Diego (UCSD), led a team that analyzed nearly 20 years of data on influenza from several countries in different regions of the world. The authors report that they uncovered a causal relationship between absolute humidity and flu outbreaks that can be either positive or negative, depending on temperature. They found a critical temperature window of 70 to 75 degrees Fahrenheit (21 to 24 degrees Celsius). Humidity levels have opposite effects above and below this temperature window.
According to the researchers, “these population-level findings could help set the stage for public health initiatives such as placing humidifiers in schools and hospitals during cold, dry temperate winters, and setting air conditioners above 75 degrees Fahrenheit to dry air in public buildings in the tropics.”
“The analysis allowed us to see what environmental factors were driving influenza,” said George Sugihara, the McQuown Chair Distinguished Professor of Natural Science at UCSD. “We found that it wasn’t one factor by itself, but the interplay of temperature and humidity together.”
Researchers at UC San Francisco and Stanford University contacted Sugihara to apply his EDM framework – an approach initially designed for forecasting and identifying drivers of nonlinear dynamic systems like fisheries – to understand flu outbreak patterns. EDM uses observational data from the field along with an intricate backbone of nonlinear mathematical theory to study complex systems whose parts interact and are always changing (http://tinyurl.com/EDM-intro).
The full publication is available here:
