In addition, there exist statistical records of individuals who have been received in hospitals or other public institutions. Finally, the data of the sick fund must be taken into account. So far as the diseases of childhood are concerned, there are no treatises covering the great mass of statistical material.
An investigation was recently made in Berlin by Neuman of three essential factors concerned in infant mortality, namely, nourishment, social position, and the effect of the summer heat. He found that breast feeding had the most favorable effect in all classes of population and that artificial feeding lessened the chance of life. This was most marked in the lowest classes and the mortality decreased as the social position rose. The age of the infant was of importance in the mortality from infant feeding. The unfavorable effect of the summer heat on the mortality was very marked.
An exact and carefully analyzed record of the mortality is kept in all civilized countries, but there are no statistics of the morbidity of the general diseases. There has been no effort to find out the number of sick in the population on a certain day or the course and outcome of diseases affecting the inhabitants. The collection of such statistics has special difficulties. Medical supervision is necessary to correctly classify the disease and its duration, and in most instances a physician is not consulted. Then the classes who call a physician most frequently arc not in sympathy with a scientific analysis of their diseases. The sta tistics of the infectious diseases are available and arc collected for hygienic reasons.
There also exist records of a portion of the population who are inmates of hospitals or institutions and also those belonging to the various benevolent societies (Krankenkasse). There is unfortunately no reliable statistical material on the diseases of childhood.
The statistics of the city of Gratz have been carefully collected and critically analyzed and can be readily understood from the following tables and diagrams. The older ages are included so as to give a proper understanding of the morbidity in childhood.
We have chosen nine of the commoner infectious diseases for our statistics, namely diphtheria, whooping-cough, measles, mumps, ery sipelas, German measles, chicken-pox, scarlet fever, and typhoid. The reporting of tuberculosis is not obligatory,* and the other infectious diseases are so rare in children that they are not included. Influenza
is so irregularly and incorrectly reported that its records are not reliable.
The omission of tuberculosis in a consideration of morbidity in child hood is unfortunately necessary in this statistical survey because here tofore there was no available material. Later in‘restigations have shown conclusively that tuberculosis should be regarded as a disease of child hood. (See Sehlossman, Tuberculosis. Vol. II.) The number of the nine infectious diseases mentioned above occur ring in 100 cases of illness in a single year and in each year of life is shown in the following tables: Table 9 and diagrams Fig. 22, show the morbidity relation up to the thirtieth year. The morbidity of all the diseases together is portrayed in diagram The easily explainable frequency of the infec tious diseases during the school age of children is well shown. Diagrams a,—a, show plainly what are termed "children's diseases," and how they run a different course. Whooping-cough is of like frequency in the first years of life, while measles, diphtheria, scarlet fever, and chicken-pox commence in the first years and quickly reach the maximum. Mumps and German measles show a somewhat different course, the sharp rise in the curve coining later, about the eighth year, and then quickly falling in the following years.
In Table 10 and diagrams Fig. 23b,--b, are shown how many of the nine infectious diseases occur in 100 cases of infectious diseases in each year of life. These will show which infectious diseases are to be feared in the different years of life.
Table 11 and diagrams Fig. show the division of the diseases in the different calendar months. We find that the infectious diseases are less frequent in August and September and show a steady increase until March and April and a steady decrease until August.
The figures used in Table 11 are of diseases occurring from 1900 to 1908. The material used in Tables 9 and 10 are from 1905 to 1908. The courses of the different diseases during each single year show a marked similarity. We find, however, an exception in measles (Fig. 25), which shows a longer interval independent of the time of year. One epidemic begins suddenly and generally reaches its high mark in a shorter time.
After the susceptible age has been infected there will come a long pause, as shown in the diagram.