to be freed from its presence, namely, England, Portugal and
Spain. From all these it finally disappeared about 1680, at the
close of a period of pandemic prevalence. Northern and central
Europe became free about 1714, and the south of France in
1722. The last outbreak in northern Russia occurred in 1770.
After this plague only appeared in the south-east of Europe,
where in turn it gradually died away during the first half of the
19th century. In 1841 its long reign on this continent came to
an end with an isolated outbreak in Turkey. From that time
until quite recently it remained extinct, except in the East.
The province of Astrakhan, where a very small and limited outbreak
occurred in 1878, is politically in Europe, but geographically
It belongs rather to Asia. And even in the East plague
was confined to more or less clearly localized epidemics; it showed
no power of pandemic diffusion. In short, if we regard the history
of this disease as a whole, it appears to have lost such
power from the time of the Great Plague of London in 1665,
which was part of a pandemic wave, until the present day.
There was not merely a gradual withdrawal eastwards lasting
nearly two hundred years, but the outbreaks which occurred
during that period, violent as some of them were, showed a
constantly diminishing power of diffusion and an increasing
tendency to localization. The sudden reversal of that long
process is therefore a very remarkable occurrence. Emerging
from the remote endemic centres to which it had retreated,
plague has once more taken its place among the zymotic diseases
with which Western communities have to reckon, and that
which has for more than a century been little more than a name
and a tradition has become the familiar object of investigation,
carried on with all the ardour and all the resources of modern
science. In what follows an attempt will be made to summarize
the facts and indicate the conclusions to be drawn from recent
experience.
Diffusion.—At the outset it is characteristic of this subtle disorder that the present pandemic diffusion cannot be traced with certainty to a definite time or place of origin. Herein it differs notably from other exotic diseases liable to similar diffusion. For instance, the last visitation of cholera could be traced clearly and definitely to a point of origin in northern India in the spring of 1892, and could be followed thence step by step in its march westward (see Cholera). Similarly, though not with equal precision, the last 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 eventually invaded every inhabited part of the globe (see Influenza). 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, (1) the district of Assyr in Arabia, on the eastern shore of the Red Sea; (2) parts of Mesopotamia and Persia; (3) the district of Garwhal and Kumaon in the North-West Provinces of India; (4) Yunnan in China; (5) East and Central Africa. The last was recently discovered by Dr Koch. It includes the district of Kisiba in German East Africa, and extends into Uganda. In applying the term “endemic centres” to these localities, no very precise meaning can be attached to the word. They are for the most part so remote, and the information about them so scanty, that our knowledge is largely guesswork. What we mean is that there is evidence to show that under various names a disease identical with plague has been more or less continuously prevalent for a number of years, but how long and how continuously is not known Whether any of them are permanent homes of plague the evidence does not enable us to say. They seem, at any rate, to have harboured it since its disappearance from Europe, and probably further investigation would disclose a still wider prevalence. For instance, there are good reasons for believing that the island of Réunion has been subject, since 1840 or thereabouts, to outbreaks under the name of “ lymphangite infectieuse, ” an elegant euphemism characteristically French. In all the countries named plague appears to behave very much as it used to do in Europe from the time of the Black Death onwards. That is to say, there are periods of quiescence, with epidemic outbreaks which attract notice at irregular intervals.
Taking up the story at the point where the earlier historical summary leaves off, we get the following list of countries in which plague is known to have been present in each year (see Local Government Board's Reports): 1880, 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 mahamari); 1892, Mesopotamia, Persia, China, Russia (in central Asia); 1893, Arabia, China, Russia and India (as mahamari); 1894, Arabia, 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, Réunion, Egypt, European Russia, Portugal, Sandwich Islands, New Caledonia, Paraguay, Argentine, 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.
This list is probably by no means exhaustive, but it sufficiently indicates in a summary fashion the extent of that wave of diffusion which set in during the closing years of the 19th century. It did not fully gather way till 1896, when plague appeared in Bombay, but our modern knowledge of the disease dates from 1894, when it attacked Hong Kong and first presented itself to accurate observation. From this point a more detailed account may be given. Plague was recognized at Hong Kong in May 1894, and there can be little doubt that it was imported from Canton, where a violent outbreak-said to have caused 100,000 deaths-was in progress a few months earlier, being part of an extensive wave of infection which is believed to have come originally out of the province of Yunnan, one of the recognized endemic centres, and to have invaded a large number of places in that part of China, including Pakhoi and other seaports. Hong Kong was severely affected, and has never since been entirely free from plague. In two intermediate years—1895 and 1897—very few cases were recorded, but more recently the epidemic has gathered force again. The following table gives the cases and deaths in each of the six years 1894–1899:—
| Year. | Cases. | Deaths. | Case Mortality. |
| % | |||
| 1894 | 2833 | 2550 | 90 |
| 1895 | 45 | 36 | 80 |
| 1896 | 1204 | 1078 | 89 |
| 1897 | 21 | 18 | 85 |
| 1898 | 1320 | 1175 | 89 |
| 1899 | 1486 | 1415 | 95 |
| Total | 6909 | 6272 | 90·7 |
The excessively high rate of mortality is probably due in part to under-statement of the number of cases. Concealment is practised by the Chinese, who are chiefly attacked, and it is easier to conceal sickness than death. Plague appears to have been equally persistent and destructive on the mainland in southern China during the period indicated, but no accurate details are available. In 1897 the Portuguese settlements of Lappa and Macao were invaded. In addition to the provinces of Yunnan, Kwang-si and Kwang-tung in southern China, plague is reported to have been present for several years in a district in Mongolia to the north of Peking, and distant about “twelve days' ride.” More recently several localities in Mongolia and Manchuria have been affected. Formosa was attacked in 1896, and suffered considerably in subsequent years; in 1899 the Japanese government officially reported 2633 cases, with
