Influenza Virus

Abstract

Epidemics of disease similar to influenza have been described almost from the beginning of recorded history. Although complete descriptions began in the 16th century, historic records of influenza and influenza-like illness were made by Hippocrates in the 5th century BC.¹ The epidemic behavior of the illness enables historians to identify accounts of influenza-like illness in the Middle Ages. The origin of the term influenza is unclear, but it is thought to have one of two origins. During the epidemic of 1504 documents suggested the Italians thought the illness was due to the “influence of the stars.” It has also been referred to by some historians as influenza di redo or the “influence of the cold.” The term influenza was later adopted by the English during the epidemic of 1782. The first influenza virus was isolated from a chicken with fowl plague in 1901, but it was not recognized as an influenza A virus until 1955. In 1933 Smith et al were the first to recover an influenza A virus from a human subject.² Influenza B virus was isolated by Francis in 1940.³