2/8 DISEASES DUE TO HELMINTHS 



THE FILARIASES. 

 THE CHIEF CAUSATIVE PARASITE. 



This is the Filaria bancrofti as described above. 

 Its position among the Nematodes can be seen at a glance by refer- 

 ing to the table on p. 232. 



DISTRIBUTION. 



Asia is perhaps the endemic home of the disease. From thence it 

 probably passed to Africa, from thence to America, from the Southern 

 United States downwards. 



It is also present in Australasia. 



It is more common along the sea coasts and the banks of large 

 rivers. 



High air temperatures and considerable atmospheric humidity seem 

 to assist its spread. 



Bahr concludes that at one time or other every Fijian is the subject 

 of filariasis. 



50 per cent, of the Samoans are infected. 



S3 per cent, of the people of Cochin in India car^y it. 



KNOWN CARRIERS OF THE WORM. 



Culex fatigans. 



Stegomyia pseudo-scutellaris. 



Mansonia uniformis. 



,, pseudo-titillans. 



Pyretophorus costal is. 

 Myzomyia rossii. 

 Myzorhynchus nigerrimus. 



,, minutus. 



Cellia albimana. 



The worm is capable of undergoing part of its development in 

 certain other mosquitoes. 



PATHOLOGY. 



The parent worm may not produce any ill-efTects, but — 



(i) If it obstructs a lymph trunk the mechanical pressure of the 

 retained lymph damages the tributar)- channels, or 



(2) If the parent is injured abortion may ensue, when oval eggs 

 instead of elongated embryos are passed, and these eggs being thicker 

 than the embryo are liable to block up the lymph channel of the skin 

 or lymphatic gland. 



Heavy infections with parent worms have not yet been described. 



It must be remembered, however, that few post-mortems have been 

 recorded. The adults are difficult to find. When there are varicose 

 lymphatics or lymphatic glands with clear lymph, look for the obstruc- 



