﻿PARAGONIMIASIS IN THE PHILIPPINES. 53 



true in some other parasitic diseases, the infection seems to become more 

 active in an already established lesion, let us say of tuberculous origin. 



The abscesses arc the characteristic lesions and they have been de- 

 scribed in almost every article dealing with the disease. In brief they con- 

 sist of three zones, the central one made up of necrotic tissue, degenerated 

 cells and often of eggs or fragments of eggs; the middle coat consists of 

 a more or less thick and dense fibrous capsule, formed of proliferated 

 connective tissue, infiltrated to a moderate degree with round cells and 

 sometimes with eggs. Its inner wall may be smooth and lined with 

 epithelial cells, but it is often granular. The outer zone is one of 

 moderate congestion, with proliferation of blood vessels and it is contin- 

 uous with the surrounding tissues. 



However, there is another type of abscess encountered most often in 

 organs such as the prostate, epididymis, and the lymphatic glands, which 

 histologically as well as in gross appearance more closely resembles an 

 ordinary pyogenic abscess, and were it not for the presence of eggs or 

 parasites such would surely be the diagnosis in many of these cases. 



Ulcerative lesions are formed by the breaking through the mucosa or 

 skin of any of the types already discussed, as a result of pressure, necrosis, 

 thrombosis, or otherwise. This most often happens when the underlying 

 lesion is an abscess, but it may take place with other types. In the 

 intestine, the striking fact about these lesions is the usual absence of 

 eggs or parasites in the mucosa, whereas the submucosa and deeper 

 structures often contain them in large numbers and discharge them 

 through the opening into the lumen of the bowel. This relative im- 

 munity of the mucous membranes to Paragonimus infection has already 

 been mentioned, and it is in striking contrast to that with Schistosoma 

 for example, where the mucosa is often infiltrated with eggs. 



In the lungs this ulcerative process is probably the mode of formation 

 of the bronchiectatic cavities. This is more probable than the belief 

 that they result from a direct attack on the mucosa, or that they follow 

 occlusion of a bronchus. In either case, the bronchial wall can and 

 sometimes does take part in the formation of the abscess wall, but this, 

 as has been emphasized by some writers, is not the rule. A moderate 

 peribronchitis of quite general distribution in the smaller tubes is quite 

 common in extensive lung involvement, but is more the result of the 

 chronic bronchitis than of a direct influence by P. westermanii. 



In the intestine, just as in the lung, the deeper structures and coats 

 seem to be primarily involved, and the infection spreads through the 

 subperitoneal muscular and submucous coats, often rinding an outlet by 

 ulceration of the mucosa. Frequently, however, ulceration does not take 

 place even when tumors of the mucosa are pushed into the lumen of the 

 bowel. Sections of one of this variety of lesion show a thickening of 

 the connective-tissue layers, with proliferation of the fixed cells and 



