ee ee ee 
— - = Se Oe 
486 
thirty years two extensive outbreaks have traversed Japan from the south 
to the north, the first, and lesser one, beginning in Kiushu in the interval 
between 1883 and 1885. It was only in 1885 that it extended into 
Shikoku and in the next year (1886) into the western parts of Honshu, 
from which latter portion of the country it soon disappeared, not reaching 
farther toward the north. ‘The second and larger one, in its movement, 
can be described very graphically. Between 1892 and 1894 a great 
epidemic of the disease again appeared in Kiushu, the number of the 
sick reaching nearly 45,000 to 50,000; in 1895 it suddenly lessened so 
that the patients decreased to about 14,000, and in the next year they 
further diminished to about 6,000. Meanwhile, in 1893 the epidemic 
pushed forward into Shikoku, reaching its maximum in 1894, the number 
affected being 34,600, and from this point it extended into Honshu, 
however, only being observed in the western provinces of this district 
in 1895—that is, two years after its appearance in Shikoku. In 1896 
the disease extended to the central province, and during three years it 
ravaged that district with frightful intensity. Just as it was beginning 
to diminish samewhat in this latter region it suddenly appeared in the 
western provinces, in which portion of Japan it reached its highest point, 
so that there the number of cases reached 60,700 in 1899. Up to the 
present time this great epidemic has never appeared with any degree of 
intensity in Hokkaido, the northernmost of the large islands of the 
Empire, probably because of the cold climate—for in that portion of 
the country we have only encountered some hundreds of cases in one 
year. ‘ 
As has been seen, the great waves of the epidemic of dysentery grad- 
ually rolled from the south toward the north, the greatest amplitude in 
one and the same region remaining during one to three years. After 
reaching its maximum, it suddenly diminished, to repeat itself, as sta- 
tistics show, at intervals of from ten to twenty years. This interesting 
phenomenon can probably be explained through the immunity to dysen- 
tery which persists for a certain time after infection with the disease. 
About thirty years ago (1879) an extensive epidemic of dysentery ap- 
peared in the northern provinces of Honshu although, at about this time, 
only a few cases were observed in other portions of Japan. I regard 
this outbreak in the north as the termination of a great one which prob- 
ably also traveled from the south to the north and which represented the 
ultimate extensions of the epidemic. Owing to these considerations I 
believe the conclusion to be justified that great epidemics of dysentery 
will threaten us every ten to twenty years if we can not limit them by 
modern methods of prophylaxis. A detailed study of the prevalence of 
dysentery in individual localities strengthens this assumption. 
Upon the appearance of dysentery in small cities or villages, almost 
all susceptible persons contract the disease, so that, in Japan, it is not 
unusual to encounter 5 to 10 per cent of the entire population of a village 
