Bacteria, Viruses, and Protists

Virus Basics

What is influenza?

It is an infectious, acute respiratory disease commonly called the “flu,” caused by RNA viruses of the family Orthomyxoviridae (the actual influenza viruses). It is transmitted most often through the air by coughs or sneezing, which is why it can spread so fast. The flu is characterized by fever, chills, headache, generalized muscular aches, and a frequent cough; it can also lead to viral or bacterial pneumonia or secondary bacterial pneumonia—even for healthy individuals. In fact, influenza affects people of all ages, but can be particularly severe for the very young, the very old, and people with complications due to other diseases.


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