4 ,6 THE ANIMAL PARASITES OF MAN 



The adult worms inhabit the connective tissue at the base of 

 the mesentery, especially in the region of the pancreas, abdominal 

 aorta and suprarenals. To find them the mesentery should be 

 removed, placed in a 2 per cent, solution of formalin, and then 

 carefully examined at leisure. 



Mikrofilaria perstans. 160 JJL to 210 \L by 5 //, to 6 //, broad. Has no 

 sheath. Cuticle transversely striated. Tail rounded off, not pointed. 

 Nerve ring at 34 /*. Excretory pore 49 //,, genital pore 125/1, f rom 

 head. Smaller larvae 90 //, to no p by 4 p broad. A " fang " is also 

 described on the head. 



Mf. perstans. Mf. demarquayi. 



(1) Tail stumpy. (i) Tail pointed. 



(2) Column of nuclei extends to tip of (2) Does not extend to tip. 



tail. 



Periodicity. N one. 

 Life-history. U nknown . 



Geographical Distribution. Very common in many parts of Africa : 

 Sierra Leone, Dahomey, Northern Nigeria, Southern Nigeria, Came- 

 roons, Ivory Coast, Gold Coast, Old Calabar, Congo, Uganda. Absent 

 from Zululand, Basutoland. On the East Coast of Africa it is not 

 found in the towns of Zanzibar and Mombasa, neither is it found in 

 the country of the Masi, nor amongst the Kavirondo, who dwell 

 along the north-east shores of Lake Victoria. 



In South America, Ac. perstans is very common amongst the 

 aboriginal Indians in the interior of British Guiana. However, 

 it is not found in Georgetown and in New Amsterdam, neither is 

 it found in the cultivated strip of coast lying between these two 

 towns, but it is common on the coast farther north near the Vene- 

 zuelan boundary, where the forests stretch to the sea. The Wai an 

 Indians, who live at the mouth of the Waini river, harbour this 

 parasite. It is absent in the West Indies. 



Topographically, Ac. perstans is found only in areas covered by 

 dense forest growth and abounding in swamps. In Kavirondo, 

 where the forest disappears and the land is covered with scrub and 

 short grass, it is not found ; likewise it is not found on the grassy 

 plains of the highlands of British East Africa. Towns and cultivated 

 areas are free from it. 



Genus. Dirofilaria. Railliet and Henry, 1911. 

 Body very long, thread-like, cuticle transversely striated. Mouth 

 with six papillae. Male tail spiral with voluminous pre-anal and some 

 large post-anal papillae ; spicules unequal. Vulva near the anterior 

 hundredth of body; viviparous. Parasitic in heart or blood-vessels 

 and subcutaneous tissue. 



