﻿PARAGONIMIASIS IN THE PHILIPPINES. 37 



life cycle of the parasite is further elucidated. Considering the facts 

 which are available, it has generally been supposed that the infection is 

 taken into the gastrointestinal canal through food or drink. However, 

 it has been difficult to reconcile this conclusion with the next, quite 

 generally accepted, statement that the lungs are the primary seat of 

 lesions and, indeed, are the only organs involved in many of the cases. 

 Several observers believe that the worms reach the lungs by wandering 

 from the oesophagus into the trachea and then through the bronchial 

 tubes. Katsurada considered that the young worms could bore through 

 the intestinal .wall and reach the lungs by the lymphatics and Yama- 

 giwa thought that they could enter them by penetrating directly through 

 organs and tissues. All have agreed that the brain lesions which are 

 often encountered are secondary to the pulmonary ones, and that the 

 infection reached this organ through the blood vessels. 



Considering our present knowledge of the subject, infection through 

 the gastro-intestinal canal must be accepted but the possibility of infec- 

 tion through the sound or broken skin can not be excluded. Further- 

 more, from the facts brought out in this report,' the lungs can not be 

 considered as the primary seat of lesions nor even in many cases as the 

 most important organs involved. 



The observations made in Manila further convince me that the spread 

 of the infection, when it is once established, is chiefly by the lymphatics, 

 as was originally pointed out by Katsurada. Many facts tend to sup- 

 port these statements. In the first place, in at least one of my cases the 

 lungs were not at all involved and in one instance, they were the 

 only organs infected. All the findings are compatible with the theory 

 of gastro-intestinal infection, spread by lymphatics. Even the lung 

 lesions often bear out this view, for, as we shall presently see, the major- 

 ity of the lesions are not of the bronehiectatic type as it is generally 

 considered, but they bear a closer relation to the lymphatic system. 



VII. PATHOLOGY. 



The articles dealing with the pathology of this infection prior to 1899 

 bave been well summarized by Stiles and Hassall; the most important 

 ones since that time have been those of Katsurada, Scheube and of Looss. 

 Taken together, these discussions hardly present an adequate picture of 

 the pathology of the disease as it has been seen in Manila. 



In general in my cases, the distribution and severity of the lesions have 

 been greater than is usually recognized to be the case by other writers, 

 and the lung lesions are not as predominant as they have been accredited 

 with being in other localities where the disease is endemic. 



