generally developed in connection with the digestive system, acute and infective diseases of which system increase towards autumn. The accompanying diagram (1) is reproduced from the DIAGRAM 1.-ENTERIC FEVER (22 YEARS 1869-90). -50 per cent The mean line represents an average weekly number of 16 deaths. FIG. 69. MEAN LINE Annual Summary of the Registrar-General for England for 1890:-Temperature and Hot, dry, Moisture. calm summers increase the prevalence of enteric fever, which is less frequent in cold, wet, stormy seasons. Warm, damp weather, however, predisposes to the disease. Floods occurring in badly drained localities may impregnate sources of drinkingwater with the germs of enteric fever, and so lead to its outbreak. Soil and Underground Water.1-Professor von Pettenkofer 1 An excellent résumé of various papers on this subject in the Zeitschrift für Biologie will be found in the Ugeskrift for Læger, Copenhagen, January 30, 1869. A translation by my father, Dr. W. D. Moore, appeared in the Dubl. Journ. of Med. Science, vol. xlvii. p. 497, May 1869. and Professor Buhl, of Munich, have shown that when the subsoil water in that city (as measured by the depth of water in the surface wells) is falling the number of cases of enteric fever increases; when the water level is rising the number of cases diminishes. Liebermeister and Buchanan suppose that these observations simply illustrate the mode in which the disease is communicated by means of drinking-water. When the subsoil water is low any noxious matters in it accumulate and acquire a greater virulence. In the case of an outbreak of enteric fever at Terling, Essex, in December 1867, Dr. Thorne Thorne, then an Inspector, and now Medical Officer, of the Local Government Board of England, found that the disease had broken out with great severity precisely when the wells were high.1 Two or three years after the introduction of the Vartry Water Supply into Dublin, in 1868, a serious local outbreak of enteric fever took place in Trinity College, Dublin. It was confined to the resident water-drinkers in the College. An inquiry was instituted into the cause of the outbreak, the Rev. Dr. Haughton, F.R.S., Fellow of Trinity College, Dr. Apjohn, F.R.S., then Professor of Chemistry in the University of Dublin, and Mr. Dowling, then Professor of Engineering in the University, being appointed to act as Commissioners by the Rev. H. Lloyd, D.D., at the time Provost of Trinity College. It was found that, owing to high tides in the river Liffey, and the accumulation of water in the subsoil, in consequence partly of the disuse of the pumps after the introduction of the Vartry water, and partly of the leakage of the Vartry water itself from defective house-drains, the foul subsoil water had overflowed into and contaminated the well within the College precincts from which the drinking-water in use in the College was drawn. Ever since that time the level of the subsoil water in Trinity College has been kept low by steam pumping, at a cost of about £300 per annum, with the result that within the past twenty-three years no 1 Tenth Report of the Medical Officer of the Privy Council, p. 51. 1868. indigenous outbreak of enteric fever has occurred amongst the residents in the College. TABLE IV. Showing the Total number of Deaths from Enteric Fever in the Dublin Registration District in each of Thirteen Four-weekly Periods in the Twenty Years, 1872-91; the Average yearly number of Deaths from this Fever in the Decennial Periods, 1872-81, and 1882-91, respectively; and the Percentage of the Total Mortality from the same Fever in each of the said Periods. 1 The thirteenth period included five weeks in 1873 (no deaths), 1879 (2 deaths), 1884 (7 deaths), and 1890 (7 deaths). These 16 deaths raise the periodic averages from 13.6 to 13.8 in 1872-81, and from 18 8 to 20-2 in 1882-91, and the yearly averages from 169'0 to 169.2 in 1872-81, and from 156 7 to 158 1 in 1882-91. The preceding Table supplies information as to the seasonal mortality from enteric fever in Dublin in the twenty years ending 1891. The facts are drawn from the Reports of the Registrar-General for Ireland. In this Table the year is divided into thirteen periods of four weeks each. In each of the years 1873, 1879, 1884, and 1890, fifty-three weeks are included in order to bring the Registrar-General's statistics into agreement with the calendar. In these four additional weeks, sixteen deaths from enteric fever were registered, thus raising by so many the number of deaths recorded in the thirteenth four-week period in the Table. The Table shows that, allowance being made for a three weeks' illness before death and registration occur, enteric fever increases in prevalence and fatality towards the end of July, that is, with a rise of the subsoil temperature at 4 feet to and above the critical point of 56° F. Its epidemic character becomes pronounced in September and continues until the close of February, after which the disease becomes less frequent and deadly, reaching its spring minimum at the beginning of May. From this time to the end of June is also the period of its annual minimum, while its annual maximum takes place about the middle of November. These results agree remarkably with the curve for typhoid fever for all ages and both sexes given by Buchan and Mitchell.1 This is a well-marked curve (they say) resembling the curve for scarlatina in showing the maximal death-rate in October and November, but differing from it in the duration and phases of the minimal period. Scarlatina falls below its average in the beginning of January, typhoid fever not till the last week of February; scarlet fever has its absolute minimum period from the middle of March to the middle of May, typhoid fever from the middle of May to the end of June; scarlet fever begins steadily to rise in the second week of May, typhoid not till the beginning of July, when the heat of summer has fairly set in. 5. Typhus Fever Typhus is essentially a disease of winter and spring--that is, of the colder seasons of the year. Among the predisposing 1 "The Influence of Weather on Mortality," Journ. of the Scot. Met. Soc., vol. iv. p. 197. causes of this fever, season and atmospheric temperature are commonly included. Season. During twenty-three years, January and March were the months in which the number of admissions of typhus patients to the London Fever Hospital reached a maximumthe minimum falling in September, August, and July. This distribution was from time to time disturbed by an epidemic, outbreaks of typhus commencing and advancing irrespective of season. An examination of the Registrar-General's (Ireland) Returns of deaths from typhus in Dublin, undertaken many years ago, led me to the conclusion that the death-rate from typhus attains its maximum in January and its minimum in September. The reason for this is not far to seek. Typhus is often intimately related to overcrowding, and affections of the respiratory organs are among its most frequent complications. Hence we should expect to meet with it, especially in the colder seasons of the year. Murchison points out that typhus does not always become more prevalent with the commencement of cold weather, nor does it decline immediately on the advent of summer. He correctly infers from this that the increase of typhus in winter and spring is not so much due to the direct effect of cold as to the continued overcrowding and defective ventilation of the dwellings of the poor in cold weather. The accompanying Table gives the facts relating to the deaths from typhus in Dublin during the twenty years, 1872-91, inclusive. Apart from our present inquiry, one gratifying circumstance stands prominently out from the figures in the foregoing Table, and that is, the fact that typhus fever is practically dying out in Dublin. The number of deaths from the disease fell nearly 50 per cent to 507 from 996-in the second decennium discussed in the Table. An analysis of the Table proves that the mortality from typhus reaches a minimum in the ninth and tenth periodsAugust 13 to October 7; while the minimal death-rate from |
