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Describe Filaria bancrofti. How does this Parasite gain 

 access to Man, and what is the Result ? 



Filaria bancrofti, syn. Filaria sanguinis hominis nocturna* 

 is a blood parasite of Man jn tropical and sub-tropical 

 countries. It is long and thread-like, and the mouth is 

 without lips and unarmed. The female is from. 50 to (55 mm. 

 in length ; the male is about half as long, and it has a 

 curved tail with two unequal spicules. The mature females 

 live in the lymphatic glands; the larvae (Microfilaria ban- 

 crofti) are found in the blood. 



The intermediate host is the mosquito (various species^ 

 but chiefly Culex fatigans) which convey the larvae (or 

 Microfilariae) to Man. The larvae escape from the 

 mosquito's labium while it is in the act of " biting " j 

 being too large, they are not introduced directly into the 

 blood, they work their way through the skin. 



Culex fatigans " bites " only at night. In connection 

 with this it is noteworthy that these larvae (Microfilariae) 

 show a definite periodicity, appearing in the peripheral 

 blood circulation during the night, and retiring during the 

 day to the deeper parts, to the lungs chiefly. 



The disease caused by this parasite is filariasis. Haemato- 

 chyluria and certain forms of elephantiasis are prominent 

 symptoms. 



What is "Calabar swelling"? Name the ^Parasite which 

 causes it, and mention what you know about it 

 Life- History. 



" Calabar swelling " is a form of filariasis in Man, pre- 

 valent in West Africa, especially in the Congo region. 

 It is a transient oedematous condition (of the arms and 

 other parts of the body) due to the migratory movements 

 of the Nematode, Filaria loa, which, in its adult state, 

 lives beneath the skin. 



The larvae (Microfilaria diurna) occur in the blood, 

 appearing in the peripheral circulation during the day. 

 The larvae develop in the salivary glands of female Tabanid 

 flies of the genus Chrysops (e.g.,Chrysops dimidiata). , 



Infections of both adults and larvae have not usually 

 been found in the same individual about ths same time. 



