The most severe epidemic of infantile paralysis on record in the state of Alabama occurred during the summer and autumn of 1941, the greatest concentration of cases being in rural Walker County. One hundred and twenty-one cases in Walker County were officially reported during the epidemic; 4 sporadic cases which occurred after the epidemic had subsided were also reported. Special studies on the epidemiology and other phases of the disease were made in the county at that time.
MATERIALS OF THE STUDY
It was found during the study that the incubation period from the day of exposure until the onset of the prodromal period averaged twelve days.1 The infectious period was found to be between three days before and three days after the onset of the prodromal period.2 Of 101 cases of poliomyelitis in which the families of the victims were satisfactorily interviewed, approximately 80 per cent could