[Ecologic dynamics of infectious diseases. II. Periodic recurrence of epidemics].

The incidence of hepatitis, mumps, poliomyelitis, scarlet fever, pertussis and measles from 1954 to 1984 was studied from the annual records of infectious diseases. Fluctuations were evaluated by Fourier analysis. Periodic recurrency was detected for poliomyelitis, scarlet fever, pertussis and measles and was likely for mumps. The asynchronic fluctuation of the proportion of cases and susceptible individuals is considered to be the origin of this phenomenon. Observed fluctuations corresponded to those predicted by the models.