Just like our latest pandemic, nmnerous earlier ones had their origin upon the Asiatic continent and often in the furthermost parts of Russia, spreading over Europe from east to west. This was the case with the epidemics of 1729, 1732, 1742, 1781, 1788, 1799, 1833, 1889. Moreover, numerous other older epidemics, of which Germany seemed to be the starting point, were probably brought in from Russia, although the accounts of these epidemics are too scanty to prove this.
Besides the customary northerly course of the disease successively through Asia, Russia, and Europe, which was the case in the majority of the pandemics just mentioned, there is also, in our opinion, a southern course (epidemic of 1510 (?), 1557, 1580), in which the disease was probably carried from Russia or Asia by way of Constantinople to the south of Europe. From this point the spread northward took place; in a similar manner, the northern European course, which gradually extended toward the south, and, as history shows, with remarkable regularity finally reached Italy and Spain. The regular Russian North-European course followed the usual trade route between Russia and the other countries of Europe.
Netter and others have put forward the following hypothesis: "Just as cholera is endemic on the banks of the Ganges, and endemic epidemic in Indo-China, so influenza has its home in the interior of Asia, and its endemic epidemic domain in the bordering countries, especially Russia." As a matter of fact, influenza appears to have been epidemic here for some time.
Moreover, history teaches that in former times extensive influenza epidemics occurred, limited to North America alone, and that true pandemics appeared simultaneously in Europe and North America (A. Hirsch). From this it may be assumed that a permanent focus of disease, such as central Asia and Russia form for Europe, likewise exists in North America. The following facts, taken from the most recent pandemic, seem to support this view.
As early as May, 1889, influenza appeared in Athabasca (British North America), and in the summer of 1889 Greenland was affected by an epidemic. Of particular interest, however, is the exhaustive report of the extensive influenza epidemic which arose about the middle or toward the end of December (December 22), 1889, in the immense northwest territory of British North America, in Manitoba, the island of Vancouver, situated near the northwestern coast of America, as well as in the east, in Canada and Quebec. An importation of the disease from New York and Boston, which were attacked on December 17, into those distant lonely regions is not possible in view of the time at which the disease appeared in each locality. That we have here to deal with an independent endemic epidemic analogous to the one occurring in central Asia in July, 1889, appears also from the report. The invasion and the occurrence of influenza in these extensive territories usually take place simultaneously, even in districts widely separated from each other, between which there is no communication by means of the railroad, such as between Forts MacLeod, Saskatchewan, Prince Albert, and other military posts. Moreover, the scattered Indian colonies and tribes, among whom there is only very slight intercourse, were also attacked simultaneously by the epidemic.