Influenza

Abstract

An unusual property of influenza virus is the ability to undergo antigenic changes. This explains why new strains emerge and cause epidemics every 10 to 15 years. There is evidence that this capacity for change may be finite, as evidenced by the apparent relationship between the Asian and Hong Kong strains and viruses that caused epidemics at the turn of the century. Most infections with influenza virus are asymptomatic, even in epidemic years, but the complication of viral pneumonia carries a high mortality.