Teach Cough Hygiene Everywhere/Basic info on viruses

This module helps you whiz through the corresponding chapter on the Wikibook.

Is flu always viral? What distinguishes viruses from bacteria? Why is flu called HxNx?

Supplemental reading: http://www.nytimes.com/2012/03/06/health/amateur-biologists-are-new-fear-in-making-a-mutant-flu-virus.html?scp=4&sq=flu&st=cse