Newspaper Page Text
climate, density of population, character of preventive measures
exercised, or any other determined environmental factor. More details can be given only the briefest mention here. In order to secure reliable statistics of morbidity the Public Health Service has made special house-to-house surveys in a number of localities, ascertaining the number of persons affected, the dates of onset, and a few other simple facts accurately enumerated groups representative of the general population. Partial analysis of the results of these surveys in eight localities, giving an aggregate of 112,958 persons canvassed, shows the following as the chief facts of interest: The percentage of the population attacked varied from 15 per cent in Louisville to 53.3 per cent in San Antonio, Texas, the aggregate for the whole group being about 28 per cent. This agrees with scattered observations in the first phase of the 1889-90 epidemic, when the attaek rate seems to have varied within about these limits. The case incidence was found to be uniformly highest in child ren from 5 to 14 years old, and progressively lower in each higher age group. It was slightly higher in females than in males of corres ponding age usually higher in the white than the colored population. The ratio of pneumonia cases to total population varied from 5.3 cases per 1,000 in Spartanburg, S. C., to 24.6 per 1,000 in the smaller towns of Maryland. The pneumonia rate showed little correlation with the influenza attack rate. The ratio of deaths to population varied from 1.9 per 1,000 in Spartanburg to 6.8 in Maryland towns. The death rate was by no means parallel to the influenza attack rate, but was closely corre lated with the pneumonia rate. In other words case fatality rate of pneumonia tended to be fairly constant, around 30 per cent. The death rate was notably high in children under one year old, in adults from 20 to 40 and in persons over 60 higher in males than in females of comparable ages higher among the whites than the colored. Concerning the important question of immunity conferred by an attack of influenza, the evidence is not conclusive, but there is reason to believe that an attack during the earlier stages of the epidemic confers a considerable, but not absolute immunity in the 13.