IS TROPICAL MEDICINE AND HYGIENE 



FASCIOLID.E. 



The Fasciolidae are common flukes in many of the 

 domesticated animals, and several genera are represented 

 in man. Some of the species found are probably only 

 accidental parasites in man, as they are much more 

 common in other animals, e.g., Fasciola hepatica ; others, 

 as the Clonorchis sineusis, are only known in man. 



The known human Fasciolidae, including accidental 

 parasites, can be readily distinguished by their external 

 characters as a rule, as few species of each genus occur in 

 man. The external appearances are as follows : 



In the Fasciola, the head is a definite conical pro- 

 jection from the rest of the body, and the ventral sucker 

 is not much larger than the oral. The branched intes- 

 tine, if it contains food, can usually be seen. Fasciola 

 hepatica, an accidental parasite of man, is the represen- 

 tative of this group. 



Fasciolopsis is represented in man by at least two 

 species. In neither of these is there a definite differentia- 

 tion between the head and the rest of the worm. The 

 very large and deep ventral sucker is the striking charac- 

 teristic. In addition, the large cirrhus pouch is a con- 

 spicuous object, and in many specimens the sinuous but 

 not pouched alimentary canal can be seen. The single 

 species of Fascioletta is so small that it is not likely to be 

 confused with Fasciolopsis. 



The narrower and smaller flukes belonging to the 

 Fasciolidae have no differentiation between the head and 

 the rest of the body. They can be divided into two 

 groups : (i) those with the ventral sucker near the 

 anterior sucker, and (2) those where the ventral sucker 

 is near the middle of the ventral surface. 



(j) Of those with the ventral sucker anterior, one 

 parasite accidental in man, the Dicroccelium, can be readily 

 distinguished, as the uterus, distended with eggs, is clearly 

 visible in the posterior half of the body. The testicles, 

 which are difficult to see with the naked eye in unstained 



