3o6 DISEASES DUE TO HELMINTHS 



PATHOGENICITY. 



The worm is usually harmless although some affirm that it causes 

 appendicitis at limes; this, however, is very doubtful. 



Diarrhoea in children living in insanitary conditions is more 

 common. 



Perhaps the head is buried in the mucous membrane which makes 

 their ejection more difficult and thus disposing to bacterial infection 

 at the site of the wound. No ecchymoses are seen at the point of 

 fixation. 



The eggs can infest utensils from dust long dried and hence the 

 infection is not ah\'avs due to fa?cal contamination. 



TREATMENT. 



When there are svmptoms present treat as for ankylostomiasis. 



TRICHINIASIS. 



This is an infection of the gastro-intestinal and muscular system by 

 the nematode Trichinella spiralis of the family Trichinellida^. 



The condition caused bv the infection is of considerable importance 

 as shown bv the fact that in Hamburg alone loo inspectors were 

 employed to examine pork, the carcases numbering from 25,000 to 

 30,000 per month. This work cost /,'25,ooo annually. 



DISTRIBUTION. 



It is common in German v and in some parts of America, India and 

 China. It is rare in England and France. 



THE PARASITE. LIFE-HISTORY, &c. 



Two mammalian hosts are necessary for its development which 

 need not be of diiTerent species, but no intermediate host is required. 



The cysts are founci usual! \' in human or pig''s muscle and appear 

 as minute white specks which are the encysted larvae. Their long axis 

 lies in that of the muscle fibre. The\- measure 400 b\' 230 ^a. 



The cyst membrane is formed by inflamed connective tissue. 



The larvce may thus live for years but may become calcified and die. 



The\- are chiefly found in the muscles of the diaphragm, larynx, 

 tongue, abdominal and intercostal regions. 



These cysts are ingested alive witli the muscle fibre unless severe 

 cooking has destroyed them. The gastric juice dissolves the cyst wall 

 and the parasites emerge and pass to the intestine where they become 

 sexually mature, reaching i to 3 mm. in length. Copulation takes 

 place about tMo days after the cvsts have been ingested, after which 

 the males die. The females grow, penetrate the mucous membrane of 

 the bowel and reach the lymph spaces and there deposit living larvae. 



One adult female may give rise to 1,500 larvae. 



