Under severe epidemics, defoliation and death of branches can also occur.

To the first class belong the severe epidemics, of which chicken-cholera is the most destructive.

As a result, severe epidemics are becoming comparatively short-lived.

The U.S. Centers for Disease Control and Prevention said Washington has one of the most severe epidemics in the nation.

Colletotrichum kahawae is an emergent fungal pathogen causing severe epidemics of Coffee Berry Disease on Arabica coffee crops in Africa.

Even in the most severe epidemics all are not equally affected, some escape the infection, others have the disease lightly, others severely, some die.

According to the WHO website, the lung-based pneumonic plague is very contagious and "can trigger severe epidemics through person-to-person contact via droplets in the air".