19, 6 Lantin: Methods of Serum Application 631 
July, August, and September, after which the number of cases 
decreased. 
It is interesting to learn why there are so many cases of bacil- 
lary dysentery in Manila from July to September. 
There seems to be a good deal of evidence to show that it is 
due to the seasonal conditions prevailing in those months. In 
the Philippines the wet season usually begins in May, following 
the hot season, and from July to September a great deal of rain 
falls, as a rule. The rainy season, then, is favorable to the 
spread of the virus, by water and especially by flies, because the 
fallen rain affords them many breeding places. Flies are more 
abundant during the wet season. Pap apg tee oe te 
Flies are carriers of pathogenic _, Py 
organisms, on account of their «4 7 
mode of life; they alight andfeed ~» 
on fecal matter and then, their ~ 
bodies infected, again alight on _ ,, | 
food. Bahr,(1) in Fiji Islands, 
observed many cases of bacillary “® | 
dysentery during the wet season. | és | 
Furthermore, other diseases, { ~ 
such as typhoid fever, amebic ° * | 
dysentery, etc., the epidemiology _,, [ 
of which points to flies as the % 
carriers of the infecting micro- ‘ j 
organisms, are also prevalent in ; A 
Manila during the rainy season. 6 ] \ 
BACTERIOLOGY ¢ / 
It was established many years Fic. 2. Showing seasonal incidence. 
ago that the etiologic factors of : 
the disease are the various strains of Bacillus dysenteriz. In the 
epidemic of 1918 Shiga infection was prevalent. Out of 66 
cases in which cultures were made from stools 30 cases were 
Shiga; 7, Flexner; types undetermined, 14; negatives, 15, or 
22.72 per cent. The percentage, then, of positive cases is 77.28, 
while Cowan’s and Miller’s(2) Alexandria cases gave 41.2 per 
cent positive. 
MORBIDITY AND MORTALITY 
It is an established fact that of all the types of Bacillus 
dysenteriz, the Shiga-Kruse type is the most toxic. It is the 
deciding factor in influencing the mortality, especially if the 
