Ague is a noun that refers to a shivering fit. 

The Latin word acuta (ah KOO tah) means ‘acute fever.’ In past years, it was often used specifically to refer to malaria. More recently, it may describe any shivering fit. 

After that bad batch of berries, I was left with a shivering fit for days. That kind of ague can definitely cause you to get more selective when choosing berries to pick in the woods.