118 The Philippine Journal of Science 1923 



positive results. From the histories of the entire series of cases 

 it would be impossible to state with any degree of accuracy 

 whether or not any of the subjects had ever had typhoid fever. 

 The information elicited from a native in regard to his previous 

 physical condition is of no practical value; at least that has been 

 our usual experience with the lower-class Siamese. In view of 

 the fact that we have, during a period of five years, observed 

 no less than 35,000 patients with only two genuine cases of 

 typhoid fever being diagnosed, and also that at least 15.5 per 

 cent of all the people (based on 600 reactions) do possess 

 specific immune bodies in their blood, we feel that these people 

 now exhibit a marked degree of racial immunity to typhoid in- 

 fection. This we think is the result of having for generations 

 suffered from subinfections caused by the constant use of in- 

 fected water and food. 



Among the dysenteries we have found the bacillary types to 

 be comparatively rare. On the other hand, amoebic dysentery 

 is not at all uncommon. This tends to support the above ob- 

 servations. The complications of the disease are uncommon, 

 only four cases of liver abscess having been recognized during 

 the five-year period mentioned. 



Of the inoculation group of diseases plague is the most- 

 important epidemic infection we have to deal with. The condi- 

 tions for its propagation are ideal. There is an unlimited supply 

 of food for the rodent population, and the housing facilities 

 for the same are, as one might say, made to order. Considering 

 the fact that plague has been endemic in the country for many, 

 many years, and in view of the perfection of the conditions 

 for its spread, it is really surprising that there are not more 

 cases each year. From fig. 1 it will be seen that, since 1904 

 up to and including 1920, there have been only 1,722 cases in 

 a population of over 600,000. From the same graph it will be 

 noted that there is a marked tendency to follow a fundamental 

 wave, the cases increasing in number as well as in severity 

 and extending over a period of from three to four years. The 

 number of cases for 1921 does not appear on the graph, but 

 proved to be one of the lowest that we have had. If this fun- 

 damental periodicity is to continue, its recursion is to be antic- 

 ipated during 1922 or 1923. 



Fig. 2 is of interest in showing the relationship between the 

 average monthly incidence, the mean atmospheric temperature, 

 and the mean relative humidity. 



