Influenza (Flu; Grippe; Grip) By Brenda L Tesini, MD, University of Rochester School of Medicine and Dentistry Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Epidemiology Symptoms and Signs Diagnosis Prognosis Treatment Prevention Key Points Topic Resources Overview of Zoonotic Influenzas Influenza is a viral respiratory infection causing fever, coryza, cough, headache, and malaise.