Epidemiological evaluation of influenza in Italy.

A statistical study of the mortality from all causes and from respiratory diseases was carried out in an evaluation of the influenza epidemics in Italy from 1956 to 1973. Type A influenzaviruses were responsible for outbreaks every 2-3 years. Type B influenzavirus appeared every 4 years and accounted for a single noteworthy epidemic in 1962-63. From the analysis of data on both general mortality and respiratory mortality a better evaluation of the extent of the influenza outbreaks could be made.