DIAGNOSIS 115 



Prevention. Protection from the bites of Chrysops is 

 all that can be done at present. The life-history of these 

 species of Chrysops is unknown, and in all probability, 

 like other Tabanidce, the breeding-places are in shallows 

 at the edge of water, or in wet sand. These larvae are 

 semi-aquatic, and the eggs are deposited on twigs or 

 leaves in the vicinity of, or floating on, water. 



Treatment. The local conditions, Calabar swellings, 

 are temporary. The worms, when superficial, may be 

 removed, but it is only when they cross the conjunctiva 

 that they are troublesome. 



Diagnosis of Filarice. 



Diagnosis of Filar ice. The adults of these blood filariae 

 are difficult to find even in a post-mortem examination. 

 Such a diagnosis could only be made during the life of 

 the host in the case of those worms found near the skin. 

 In the course of an operation others, such as F. bancrofti, 

 may be found, or calcified remnants of them. 



The differential diagnosis of the filariae whose embryos 

 are found in the blood of man is not very difficult, 

 as these embryos can usually be distinguished from each 

 other. The points of value in distinguishing between 

 them are : 



(1) The presence or absence of a loose sheath. 



(2) The times during which the embryos are present in 

 the peripheral blood periodicity. 



(3) The character of the termination at the narrow 

 end. 



(4) The nuclear core and how it terminates anteriorly. 



(5) Dimensions of the embryo when alive and when 

 dried on a slide. 



(6) Position assumed by the worm in death. 



(i) The presence of a loose sheath is of great im- 

 portance. Of the embryos found in man, those of 

 F. bancrofti, F. loa, and F. philippinensis (the adult is in- 

 distinguishable from F. bancrofti) have a sheath. The 

 others have not. 



