when particular measures were taken to reduce the pollution on the Croton watershed by removing sewage discharges from houses within a 300-foot line of the reservoirs and principal feeders. The situation in the city of Philadelphia you are no doubt all familiar with. The filters, which have improved the typhoid situation to such a marked extent in this city, were introduced gradually, beginning about the year 1903. The West Philadelphia Belmont filters were added in 1906; the Torresdale plant was started in part service in 1907. By the year 1909 most of the city was supplied with filtered water, and where no filtered water was afforded the balance was sterilized. The final addition of the Queen Lane plant, in 1911, gave filtered water to the whole city. The reduction in typhoid fever as a result of this gradual introduction of filtered water into the city is very noticeable. In 1914 Chief Davis states that the annual deathrate from typhoid fever was 7.48 per 100,000. The city of Baltimore shows no very marked reduction, but, with the addition of the new water filters which will be in operation before very long, we can expect to find quite a lessening of the typhoid rate. The city of Washington showed rather disappointing results in the matter of filtration, particularly in the earlier years. Although the reduction of typhoid at first was by no means as marked as was expected in advance, yet the later figures have been much more satisfactory. The figures for the city of Cincinnati following filtration are quite remarkable. The reduction was very sharp, and the typhoid rate for the last five or six years has been only about one-third, or even less, of what it was during the preceding years. The city of Pittsburgh shows similarly satisfactory results. The introduction of filtered water in 1909 effected a very marked reduction of typhoid fever, even if some unfiltered water was still supplied. In the column showing the results in the city of St. Louis a moderately satisfactory reduction has been effected by the addition in the year 1904 of the coagulating plant to the St. Louis water works system, aided by prolonged sedimentation. arrangements and later by sterilization. Filters are now being built. The New Orleans results show some satisfactory reduction. recently, but a good deal less than has been found in other cities. Fig. 1 shows the results of the foregoing table represented graphically. The scale of the drawing does not indicate very clearly what the effect of changes in the water supply has been. A few of these curves stand out very clearly. In the upper line the reduction in the typhoid rate of the city of Pittsburgh is remarkable over all the others. The line showing the city of Cincinnati gives a very marked reduction. In the second line the effect on the city of Philadelphia is very noticeable. ANNUAL TYPHOID FEVER DEATH RATES FOR VARIOUS AMERICAN CITIES Fig. 2 shows some detailed results from the city of New Orleans. Here are plotted the deaths for each year per 100,000 population from typhoid and malaria combined. These figures are, of course, materially higher than the typhoid deaths alone, but it seems not unlikely that they represent more accurately the improvement effected by the introduction of the sanitary sewer system and the new filtered water supply. A part of the surface drainage system was put in service in 1900. Sewer connections to the sanitary sewer system were started in the year 1907 and have gradually increased. The filtered water supply was started by the city in the year 1909. From the start of the surface drainage system a very satisfactory reduction in typhoid fever and malaria is to be found. During 1913 the deaths from typhoid were seventeen per 100,000, and for malaria six, making a total of twenty-three per 100,000 population, a figure not at all unsatisfactory, when it is considered that there is still a part of the city not supplied with either sewer connections or filtered water, and that local conditions of temperature, flies, and other items, exercise a material effect on the TYPHOID & MALARIA DEATH RATE AND TOTAL DEATH RATE NEW ORLEANS-LA. typhoid and malarial fever death-rate. The removal of storm water and sewage which formerly pooled on the surface of the ground has been the controlling item. HAZEN'S THEOREM. In the year 1893 it was stated by Dr. J. J. Reinicke, of Hamburg, Germany, and Mr. Hiram F. Mills, C.E., of Lawrence, Mass., that the purification of the polluted public water supplies of Lawrence and Hamburg was producing a general decline in the death-rate of each of these cities. In 1904 Mr. Allen Hazen, in his paper on "The Purification of Water for Domestic Use before the International Engineering Congress, formulated a deduction from certain data similar to this, as follows: "This computation indicates that where one death from typhoid fever has been avoided by the use of better water, a certain number of deaths, probably two or three, from other causes have been avoided. This seems the clear and logical conclusion from the statistics." Mr. Hazen's tabulation from which he deduces this statement is the following: Reduction in total death-rate in five cities with the in- Normal reduction, due to 440 deaths per 100,000 population average of cities similarly situated, but with no radical change in water supply ... 137 deaths per 100,000 population This question was further considered in detail by Professor W. T. Sedgwick and Mr. J. Scott McNutt, in the Journal of Infectious Diseases, vol. 7, p. 489, in their paper entitled "On the Mills-Reinicke Phenomenon and Hazen's Theorem Concerning the Decrease in Mortality from Diseases other than Typhoid Fever Following the Purification of Public Water Supplies." The authors of this paper came to a conclusion as follows: "Mr. Hazen's quantitative expression for the Mills-Reinicke phenomenon, when applied to the cities which we have studied (with the exception of Watertown), appears sound and conservative. It seems likely, however, that it will be impossible in the future This general subject is dealt with by the speaker in his book on Sewage Disposal, pp. 107-16. It appears that the Hazen theorem seems to apply chiefly in those cities having formerly a grossly-polluted water supply. Where improved supplies have been installed for cities which previously had only a moderately-polluted supply the improvement in general deathrate has been far less marked than at Lawrence, Albany, Hamburg, etc. The danger of too definite conclusions as to the exact effect of the filtered water and its relative effects on the typhoid deathrate is quite great. Still greater may be the danger of any definite conclusion as to the effect of water supply on the total or general death-rate. The fact that it is impossible to attribute to improved water supply all the reduction of typhoid rate, following such introduction of improved water supplies, is shown on Fig. 3. These data are taken from a paper written by Drs. Levy and Freeman in the Old Dominion Journal of Medicine and Surgery, vol. 7, No. 5, November, 1908, and show two lines of the typhoid fever death-rate, including malaria, for the cities of Richmond, Va., and the District of Columbia, including the city of Washington. The heavy line on this diagram gives the result for the city of Richmond. During the period under consideration, from 1880 to 1909, there was practically no change made in the city of Richmond water supply. The Richmond water is not filtered, but there is no reason to believe that there was any great amount of pollution or disease resulting from this unfiltered water. In the year 1909 an additional settling basin was provided for the Richmond water supply, as noted on the digaram. The Washington water supply, as shown in the diagram, was considerably improved during this period. At the end of 1887 we note that only the Georgetown Reservoir was in use. In 1895 the Dalecarlia Reservoir was added. In 1901 the Washington Reservoir was added. The filters were put into service in 1905. |