Influenza

Abstract

INFLUENZA is an old and well established disease that has appeared in epidemics and pandemics since before the seventeenth century. Despite its long history, however, the cause or causes of both epidemic and pandemic influenza remained unknown until fifteen years ago. Since then, remarkable progress in the methods of study and knowledge of epidemic influenza has taken place: epidemic influenza has been established as a virus infection caused by one or the other of two very similar agents; methods have been devised that have permitted chemical and physical characterization of the viruses; re-evaluation of the clinical and epidemiologic nature of . . .