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Rh previously, and it was noticed that every fresh employe entering her service developed the disease. She prepared the meals of the men. On her exclusion from the kitchen the cases ceased. In Brentry reformatory, near Bristol, an outbreak numbering 28 cases was traced to a woman employed as cook and dairymaid who had had typhoid fever six years previously. Before entering the reformatory she had been cook to an institution for boarded-out girls, and during her year's residence there 25 cases had occurred. A case is reported by Huggenberger of Zurich (Lancet, October 1908) in which a woman carrier is said to have infected a series of cases lasting over 31 years, including her husband, son, daughter-in-law, and no less than nine different servants. Numerous cases of contamination of milk supplies by a “ carrier ” have been investigated, and in outbreaks traced to dairies it is wise to submit the blood of all employés to the agglutination test. A persistently high opsonic index to typhoid bacilli is notable among “ carriers.” Not only do persons who have had tyhpoid fever harbour bacilli, but also persons who come in contact with cases of the disease and who have no definite history of illness themselves. The other means of dissemination are polluted soil, food and drink, particularly milk and water. The precise mode in which polluted soil acts is not understood. The result of experiments mentioned above shows that the bacillus lives and multiplies in such soil, and epidemiological investigation has repeatedly proved that typhoid persists in localities where the ground is polluted by the leakage of sewage or by the failure to get rid of excrementitious matter. In some instances, no doubt, drinking water thus becomes contaminated and conveys the germs(but there appears to be some other factor at work, for the disease occurs under the conditions mentioned where the drinking water is free from suspicion. Exhalation is not regarded as a channel of communication. The researches of Majors Firth and Horrocks prove that dust, fiies and clothing may convey the germs. Another way in which food beoomes the medium of conveyance is by the contamination of oysters and other shellfish with sewage containing typhoid bacilli. This has been abundantly proved by investigations in Great Britain, America and France. Uncooked vegetables, such as lettuces and celery, may convey the disease in a similar way. The most familiar and important medium, however, is water. It may operate directly as drinking water or indirectly by contaminating vessels used for holding other liquids, such as milk cans. Typhoid caused by milk or cream has generally been traced to the use of polluted water for washing out the cans, or possibly adulterating their contents. There is obviously no reason why t is chain of causation should not hold good of other articles of food and drink. Outbreaks have been traced to ginger-beer and ice-creams. Water sources become contaminated directly by the inflow of drains or the deposit of excretal matter; indirectly, and more frequently, by the leakage of sewage into wells or by heavy rains which wash sewage matter and night-soil from ditches and the surface of the land into springs and watercourses. Water may further be contaminated in the mains by leakage, in domestic cisterns, and in supply pipes by suction. There is some reason to believe that the bacilli may multiply rapidly in water containing suitable nourishment in the absence of large numbers'of their natural foes.

Prevalence.-Typhoid fever is more or less endemic and liable to epidemic outbreaks all over the world. It is more prevalent in temperate than in tropical climates. The following comparative death-rates show its relative prevalence in certain countries in 1890: Italy, 658; Austria, 470; U.S.A. 462; Prussia, 204; England, 179. It has undergone marked and progressive diminution in many countries coincidently with improved sanitation; particularly in regard to drainage and water-supply. Table I. gives annual death-rates in England and Wales after 1869, when typhoid was registered separately from typhus and “ simple ” fever.

London shows less improvement than Great Britain as a whole, but it started with superior sanitary conditions, and though the reduction has not been maintained in the last recorded quinquennium, the mortality is still much below the mean. The disease is more prevalent in Paris, but the diminution effected has been far greater in the time,, the average annual mortality per million having fallen from 1430 in 1882 and 581 in 1883-1888 to 293 in 1889-1894 and 172 in 1895-1900. Other recorded instances of diminution are Berlin, Hamburg, Munich, Copenhagen, the Netherlands, Buenos Aires (from 1060 per million in 1890 to 140 in 1899). In all these and TABLE I.-Annual Mortality from Entefic Fever per Million Persons living-England and Wales.

Year. Mortality. Year. Mortality.

1869 390 1889 1 76

1870 388 1890 1 79

1871 371 1891 168

1872 377 1892 137

1873 376 1893 229

1374- 374 1894 159

1375 371 1395 175

1876 309 1896 166

1877 279 1897 156

1878 306 1898 182

1379 231 1399 199

1880 261 1900 160

1 88 1 2 12 1901 1 73

1882 229 1902 126

1883 228 1903 100

1884 236 1904 93

1885 175 1905 89

1886 184 1906 92

1887 185 1907 67

1888 172 1908 75

The diminution is more clearly shown if quinquennial periods are taken, as in Table ll.

TABLE II.-Average Annual Mortality per Million in England and Wales, and in London.

1871-75. 1876-80.1881-85. 1886-90. 1891-QS, 1896-1900. 1901-05 England and

Wales. 354 278 218 180 176 174-8 112-6

London. 256 234 226 150 156 1485

other cases the improvement is attributed either to drainage or water-supply, or both. The case of Munich is so instructive that it deserves special mention. For many years typhoid was excessively prevalent in that city. The prevalence was continuous, but aggravated by large epidemic waves, extending over several years. These gradually decreased in magnitude, and ceased towards the end of 1880. Since then the prevalence has still further diminished, the average annual mortality per million having fallen from 2024 in 1851-1860, 1478 in 1861-1870 and 1167 in 1871-1880 to 160 in 1881-1890 and 52 in 1891-1900.

It has been forcibly argued by Dr Childs (Trans. Epidem. Soc. vol. xvi.) that drinking water had little, if anything, to do with the prevalence of the disease, and that its gradual reduction was due to purification of the soil by improved drainage syétems and the abolition of slau hter-houses. The epidemic waves were found by von Pettenkoger to be associated with the rise and fall of the subsoil water; when the water fell the fever rose, and vice versa. l-le did not, however, consider that the subsoil water exercised any influence itself; he merely regarded it as an index to certain conditions of moisture which exercised a favourable or unfavourable influence on the development of the disease. His theory, which has been much misunderstood, is to some extent corroborated by some facts observed in Great Britain. One is the seasonal prevalence of typhoid, which in England is an autumnal disease. The minimum occurs in May or June; in August a marked rise begins, which continues throughout the autumn and reaches a maximum in November, after which an abrupt fall sets in. These facts are in keeping with Pettenk0fer's theory, for the subsoil water reaches its maximum height at the end of spring and falls throughout the summer and a great part of the autumn. The coincidence is further emphasized by the fact that in dry years, when the subsoil water sinks lower than usual, typhoid is more prevalent, and in wet years the contrary. A glance at the mortality table for England given above will show that the progressive improvement recorded down to 1892 was suddenly interrupted in 1893, when the rate rose abruptly from 137 to 229. That was an extraordinarily dry and hot year, and it was followed by a succession of dry and hot years, culminating in 1899, with two exceptions-1894 and 1897. In both the typhoid rate fell again, but in all the others it rose. One explanation has been suggested by l/Ir Matthew Adams of Maidstone. He points out that organic matter deposited on or in the ground asses in normal years gradually through several layers of soil, anti) undergoes a process of destruction or purification before reaching the underground water; but in hot summers the ground becomes baked' and cracked, and there is no such percolation; when rain comes everything is swept suddenly away without any purification, and finds its way into the sources of drinking water.