Influenza

Abstract

- Influenza, sometimes known as the flu, is a highly infectious respiratory infection caused by flu viruses that infect the nose, throat, and lungs. - Influenza is challenging for scientists to study because there are hundreds of strains that are classified into four main categories: 1. Type A: is the most prevalent cause of human sickness and has been the source of all significant influenza pandemics in modern history. 2. Type B: cause seasonal epidemics. 3. Type C: cause mild respiratory illness 4. Type D: not known to cause disease.