346 The Philippine Journal of Science 1915 
TABLE I.—Incidence of kedani fever in Sumatra. 









Month. Number. | Month. | Number. 
Januarya sees se eee Wal). Pily toss ee ee eee } 19) 3 
Nebruary 22-2 22-22 ss—2 ae eee 2) | ACI SUS tiea= =e ane oe. eaten nee | 19 | 
March?-.29 = sep oes Sees LOS September > Seaesnae eae en eee 7 | 
(APY ili. 52 ent eas oe tek i eee G3 ‘October Sasa stee a a ee ee 5 
May 2 eae ee cre eae Br NGvember: 2-= see cease = ae eee 25 
JUNC ee oe I SEs ene ee Nee 16. ||iecem bers 2" 202 = teens ee eee 19 
J 

From this distribution one can say that the disease occurs 
most frequently during the months of June to August (54 cases) 
and during the months of November to January (59 cases). 
These two periods are not at all alike so far as meteorological 
conditions are concerned; the period June to August is dry, 
while the period November to January is the time of greatest 
rainfall. 
MORTALITY 
The second important difference is in regard to mortality. In 
Japan it is accepted that an average mortality of about 30 per 
cent occurs; according to older writers it was as high as 70 
per cent. In advanced age the disease is especially dangerous. 
In Sumatra the mortality is only about 3 per cent, and though the 
estate laborers are for the most part young, this low mortality 
shows that despite the grave symptoms observed in its course 
the disease must be classed among the less dangerous maladies. 
Enteric fever in Deli is accompanied by a mortality of about 
15 per cent; it is much more dangerous than pseudotyphoid. 
TRANSMITTING AGENTS 
There is, also, a difference in the transmitting agents of the 
disease in the two countries. In Japan a small, red mite, 
the larval form of an unknown Trombidium, is known to be the 
infecting agent; the true host of this mite is the field mouse, 
which harbors the parasite often in large numbers about the 
ears. It has been shown experimentally by the Japanese in- 
vestigators Miyajima and Asakawa that the mite is the transmit- 
ting agent of the virus from mouse to man; they were able 
to infect monkeys by allowing mites to feed on these animals. 
Up to the present I have been unable to determine the transmit- 
ting agent of pseudotyphoid in Deli, but here, also, judging 
from the histories given by patients, it is a question of ticks 
or mites. On the estates where the disease occurs the laborers 
suffer greatly from the attacks of minute acarines, red in color 
