﻿182 The Philippine Journal of Science 1914 



Certain peculiar conditions must be taken into consideration, 

 however, in comparing the spleen rate and the parasite rate of 

 the inhabitants of San Jose. 



The population of San Jose consists chiefly of adult males and 

 of relatively few women and children. Consequently, both the 

 blood examinations and the spleen palpations in these series 

 have been made chiefly of adult males. Neither the spleen rate 

 nor the parasite rate is considered reliable in diagnosing en- 

 demic malaria unless applied to children between the ages of 1 

 and 10 years. 



Moreover, it is to be noted that the population of San Jose 

 is for the most part not a permanent but a shifting one. The 

 laborers of this estate are practically all imported, both from 

 all parts of the Philippine Islands and from abroad. They are 

 chiefly Filipinos, but include some Japanese and East Indians, 

 A few Americans and Europeans are employed to superintend 

 the work of the laborers and to perform the skilled work on 

 the plantation. The Filipino laborers, for one reason or another, 

 usually remain only for a short time at San Jose. After work- 

 ing for a few months, they return to their homes and are 

 replaced by freshly imported men. A certain proportion of 

 them return from time to time to be reemployed on the estate. 

 The company estimates that 90 per cent of their laborers remains 

 in their employ less than six months, that 9 per cent remains 

 more than six but less than twelve months, and that 1 per cent 

 remains more than one year. 



This circumstance modifies the interpretation to be placed on 

 the results of these examinations. The population being con- 

 stantly shifting, the new arrivals, unless coming from a malari- 

 ous region, would be nonimmunes. Therefore, the blood and 

 spleen examinations of the inhabitants of San Jose would show 

 not the endemic index of that region, but the incidence of infec- 

 tion with malaria among the more or less nonimmune adults. 



Of the 1,064 persons, exclusive of those who were ill with 

 fever, of whom microscopic examination of the blood was made, 

 357, or 33.55 per cent, showed malarial parasites; and of the 

 1,110 persons whose spleens were palpated 291, or 27.11 per 

 cent, showed enlargement. Therefore, if the two series should 

 coincide, approximately equal results would be obtained by the 

 two methods of diagnosis. 



Considering first the total number of persons of whom both 

 spleen palpation and microscopic examination of the blood were 

 made, Table X shows the spleen rate, the parasite rate, and the 

 percentage of agreement between the two series. 



