THE NOTIFIABLE DISEASES. PREVALENCE DURING 1922 IN CITIES OF OVER 100,000. The following tables were compiled from data furnished by the health officers of the cities. They include all cities of 100,000 population or over in the United States except Kansas City, Kans. The following is a list of the diseases included: The populations given, and which were used in computing the rates, were estimated as of July 1, 1922, except where otherwise stated. Medians of the total number of cases reported annually during the years 1913 to 1921 are given for cerebrospinal meningitis, diphtheria, measles, pellagra, poliomyelitis, scarlet fever, smallpox, and typhoid fever. The column headed "Number of years" shows the number of years for which data were available for each city. In comparing the figures for 1922 with the medians for preceding years, it should be borne in mind that for several years there has been a gradual improvement in the reporting of communicable diseases. An increase in the number of cases reported may be due to better reporting rather than to an increase in the number of cases occurring. In studying these tables it should be kept in mind that a relatively large number of reported cases of a cominunicable disease as indicated by a high case rate (and more especially when accompanied by a relatively small number of deaths, as indicated by a low fatality rate) usually means that the health department of that city is active and that the cases of the disease are being well reported by the practicing physicians. It does not usually mean that the disease is more prevalent in that city than in other cities. A high fatality rate may mean that the disease was unusually virulent in a city; that the physicians did not treat the disease in that city with the success usual elsewhere; or that the practicing physicians did not report all of their cases to the health department. On the other hand, an unusually The median has been defined as the magnitude of the middle item in an array. If the numbers of cases reported are arranged so that the greatest number reported in any one year is first, the second greatest number is second, and so on, then the number of cases in the center of the array is the median. The following illustration shows the method followed when data for five years are available: In a city reporting 69 cases in 1915, 79 cases in 1916, 71 cases in 1917, 58 cases in 1918, and 33 cases in 1919, the median is 60 cases. low fatality rate may be due to the fact that the disease in the city was unusually mild; that the physicians treated it with unusual success; that the practicing physicians reported their cases satisfactorily; or that the registration of deaths was incomplete or the assignment of the causes of death inaccurate. Cities which did not report either cases or deaths of a certain disease in 1922 are not included in the table for that disease. Seventy-three cities reported 65,539 cases of diphtheria, which is an increase of about 6 per cent over the median number reported during recent years by these cities. Measles shows an increase over the median of 22 per cent in the number of cases reported. For the year 1921, 68 cities had a combined case rate of 2.53 per thousand population. In 1922, 72 cities had a combined rate of 5.26, an increase over 1921 of more than 100 per cent in the rate. The number of reported cases of scarlet fever in 73 cities was more than 26 per cent higher than the median. Fewer cases of smallpox were reported than last year, and several cities which usually have cases of small pox at some time during the year did not report any in 1922. However, the number of deaths. from this disease showed a decided increase over recent years. This increase was confined to a few of the cities. Denver, with 248 deaths from smallpox, had more than half of the deaths reported. Kansas City, Mo., reported 63 deaths; Chicago, 15; Los Angeles, 5; Bridgeport, 4; and Salt Lake City, 3. No other city in the table reported more than 2 deaths from smallpox. The decrease in typhoid fever which has been evident for several years continued during 1922, as is shown by the fact that 73 cities. reported only a little more than half as many cases of this disease as the median for recent years. The case rate for 1922 was 0.19 per thousand population, a decrease of nearly 27 per cent from the rate for the year 1921, which rate was based on reports from 67 cities. Reported Prevalence for the Year 1922-Medians for Previous Years. |