Plague

Diffusion.-Visitations of cholera can be traced definitely to a point of origin often in India. (See CHOLERA.) Similarly, though not with equal precision, a wave of influenza was shown to have started from central Asia in the spring of 1889, to have travelled through Europe from east to west, to have been carried thence across the sea to America and the Antipodes, until it even tually invaded every inhabited part of the globe (see INFLU ENZA). In both cases no doubt remains that the all-important means of dissemination is human intercourse. The movements of plague cannot be followed in the same way. With regard to origin, several endemic centres are now recognized in Asia and Africa, namely, (I) the district of Assyr in Arabia, on the east ern shore of the Red Sea; (2) parts of Mesopotamia and Persia; (3) the district of Garhwal and Kumaon in the North-West Prov inces of India; (4) Yunnan in China; (5) East and Central Africa. The last was discovered by Dr. Koch.

The following is a list of countries in which plague is known to have been present in each year (see Local Government Board's Reports) : 188o, Mesopotamia; 1881, Mesopotamia, Persia and China; 1882, Persia and China; 1883, China; 1884, China and India (as mahamari); 1885, Persia; 1886, 1887, 1888, India (as mahamari); 1889, Arabia, Persia and China; 1890, Arabia, Persia and China; 1891, Arabia, China and India (as ma/zamari) ; 1892, Mesopotamia, Persia, China, Russia (in central Asia) ; 1893, Arabia, Persia, China, Japan, Russia, East Africa, Madagascar and China and India (as mahamari); 1895, Arabia and China ; 1896, Arabia, Asia Minor, China, Japan, Russia and India (Bombay); 1897, Arabia, China, Japan, India, Russia and East Africa; 1898, Arabia, Persia, China, Japan, Russia, East Africa, Madagascar and Vienna; 1899, Arabia, Persia, China, Japan, Mesopotamia, East Africa, West Africa, Philippine Islands, Straits Settlements, Madagascar, Mauritius, Reunion, Egypt, European Russia, Portugal, Sandwich Islands, New Caledonia, Paraguay, Argen tine, Brazil: 1900, to the foregoing should be added Turkey, Australia, California, Mexico and Glasgow; in 1901, South Africa and in 1902 Russia, chiefly at Odessa.

In 1896 plague appeared in the city of Bombay; the infection spread gradually and slowly at first, but during the first three months of 1897 not only was the town of Bombay severely affected, but district after district in the presidency was attacked, notably Poona, Karachi, Cutch Mandvi, Bhiwandi and Daman. The following figures give the mortality for Bombay and Bengal, as well as the total mortality in India.

In 1900, there was an outbreak of plague in Australia. The total number of cases reported in Queensland was only 123, with 53 deaths. In Sydney there were 303 cases, with 103 deaths, a case mortality of 34%. The infection is supposed to have been brought from Noumea, in New Caledonia, where it was present at the end of 1899. Plague in Glasgow was on a still smaller scale.

It began, so far as could be ascertained, in August 1900, and during the two months it lasted there were 34 cases and 15 deaths. Once more the disease was not at first recognized, and its origin could not be traced. In 1901 plague invaded South Africa, and obtained a distinct footing both at Cape Town and Port Eliza beth. The total number of cases down to July was 76o, with 362 deaths; the number of Europeans attacked was 196, with 68 deaths, the rest being natives, Malays, Indians, Chinese and negroes. With regard to Great Britain, a few ship-borne cases had to be dealt with at the ports.

Causation.

Plague is a specific infectious fever, caused by the bacillus pestis, which was identified in 1894 by Kitasato, and subsequently, but independently, by Yersin (see BACTERIA and DISEASE). It is found in the buboes in ordinary cases, in the blood in the so-called "septicaemic" cases, and in the sputum of pneu monic cases. It may also be present in the urine. Post mortem it is found in great abundance in the spleen and liver. Nothing is known of its natural history outside the body, but on cultivation it is apt to undergo numerous involution forms. Its presence in a patient is regarded as positive diagnostic proof of plague; but failure to find or to identify it does not possess an equal negative value, and should not be too readily accepted. It is quite clear, from the extreme variations in the severity of the illness, that the resisting power of individuals varies greatly. According to the Plague Research Committee of Bombay, the predisposing causes are "those leading to a lower state of vitality," of which insuffi cient food is probably the most important. There is no evidence that age, sex or race exercises a distinct predisposing influence. The largest incidence in Bombay was on young adults; but then they are more numerous and more exposed to infection, because they go about more than the younger and the older. Similarly, the comparative immunity of Europeans in the East may be ex plained by their different conditions of life. It is doubtful whether the distinction drawn between pestis minor and pestis major has a real aetiological basis. Very mild cases occurring in the course of an outbreak of typical plague may be explained by greater power of resistance in individuals, but the epidemic prevalence of a mild illness preceding the appearance of undoubted plague sug gests some difference or modification of the exciting cause. Of course plague does not stand alone in this respect. Epidemic out breaks of other diseases—for instance, cholera, diphtheria and typhoid fever—are often preceded and followed by the preva lence of mild illness of an allied type.