But while the climate-disease link has been long appreciated, the nature of that link has been shrouded in mystery. Just as the weather is complicated, so too are the innumerable factors that dictate who gets sick from an infectious agent as well as when and why. Combining climate and disease variables into a predictive model—one that might offer early warning of a pending, weather-driven epidemic—is no easy task.

Illustration: Darren Booth; Photo: Brian Ulrich