Page:Popular Science Monthly Volume 52.djvu/315

Rh would require far more space than is available at present. It prevails as an endemic disease in all the inhabited parts of Europe, Asia, and America, and the occurrence of epidemic outbreaks depends largely upon an unusual degree of contamination of the water supply of a community by the discharges of those sick with the disease. It may prevail at any season, but as a rule the autumn months afford more cases than occur at other seasons of the year. It is more prevalent in the temperate zone than in the tropics, but in the Orient it claims many victims in tropical regions, and especially in the densely populated portions of India.

Extended experience gained in this country and in Europe shows that the relation of this disease to local insanitary conditions is very marked, and that the typhoid mortality rate is a good index of the general hygienic conditions of a town or city, especially as regards purity of water supply and efficiency of sewage disposal.

Asiatic cholera is a fatal pestilential disease which has its permanent habitat in India, and which during the present century has repeatedly invaded the countries of Europe, and has even crossed the Atlantic and prevailed as an epidemic in certain portions of the western hemisphere. In India it has, no doubt, prevailed from a remote period, and its chief endemic seat in that country appears to be in lower Bengal. The deaths from cholera in the various provinces of India during the five years from 1871 to 1875 amounted to more than seven hundred and fifty thousand.

As regards its epidemic extension to the countries of Europe, cholera is a disease of the present century. The first great epidemic dates from the year 1817, and the disease did not disappear from European soil until 1823. A second period of prevalence in Europe lasted from 1826 to 1837, a third from 1846 to 1863, a fourth from 1865 to 1875, and the fifth and last from 1892 to the present date. The time at my disposal will not permit me to trace the origin and progress of these epidemics; but the general statement may be made that they had their origin in India, and that the progress of the disease was along routes of travel, showing that its propagation depends upon human intercourse. Since the discovery of the cholera spirillum by Koch, in 1884, the method in which the disease is spread has been established in a most satisfactory manner. We now know that the germs of the disease are found in immense numbers in the intestine of cholera patients, and even in individuals who have been exposed to infection, but who manifest no symptoms of the disease other than a slight diarrhœa. Such persons sow cholera seed with the discharges from their bowels, and under favorable conditions rapid multiplication of the germ occurs outside of the body. Infection usually occurs by the ingestion of water or food