Fig. 1.

Predicting influenza among imported cases based on the time since immigration. The mechanism and timing of importation: spending k days for travel, an exposure occurs in country A with a risk proportional to the incidence. Entering country B, the exposed individual develops illness at t days since immigration. Since an infection event is not directly observable, the exact length of the incubation period has to be inferred by addressing censoring and using an explicitly infection-age structured model.