ABSTRACT
The influenza virus evolves via mutation and mixing among and between humans and other animal species. This evolution allows the influenza virus to escape immune responses which are directed at a specific strain. Influenza viruses are members of the family Orthomyxoviridae. There are three types of influenza virus: influenza A, influenza B, and influenza C. The “Spanish Flu” pandemic in 1918–1919 had the largest human impact of any recorded influenza epidemic and is without a doubt one of the more dramatic events of recorded medical history. Direct medical costs only make up a fraction of the economic consequences of influenza, though a typical case of influenza is associated with three days lost from work or school. The Advisory Committee on Immunization Practices issues yearly updated recommendations for influenza vaccination through the Centers for Disease Control. Antiviral medicines active against influenza virus include the neuraminidase inhibitors oseltamivir, peramivir, and zanamivir, and the M2 inhibitors amantadine and rimantadine.
