Fabio Sanchez

Every year in Costa Rica, dengue fever arrives like the rainy season: people expect it, they prepare for it, but the exact rhythm of outbreaks has remained a mystery. In some cantons, the disease flares up every year; in others, every two or three years.

The orchestra plays without a conductor. We know the overall volume: that's the basic reproduction number R0, the spectral radius of the epidemic. But the score itself, the contact matrix between people of different ages, holds the melody: who spreads the infection and who takes the main blow.