CLONORCHIS SINENSIS 



579 



History. — Clonorchis sinensis was first discovered by McConnell 

 in 1874 in the liver of a Chinaman. It was beheved to be an 

 Opisthorchis, but in 1907 Looss gave reasons why it should be 

 placed in the new genus Clonorchis. As far as is known it occurs 

 principally in China and Japan, and has not yet been found in 

 animals. 



Remarks. — -It may be the same as Clonorchis endemicus Baelz, 

 1883; Distoma hepatis endemicum sive perniciosunt Baelz, 1883; 

 Distoma japonicum R. Blanchard, 1886. In 1883 flukes were 

 first described in the liver of human beings in Japan by Kiyono, 

 Nakahama, Suga, and Yamagata, and a little later in the same 

 year Baelz reported the occurrence of two hepatic distoma in 

 Japan. 



1. Distoma hepatis innocuum, up to 20 millimetres in length, with 

 a Ughter-coloured uterus of larger volume, with sUghtly larger ova, 

 21 to 36 ijb in length by 18 to 20 p. in breadth, and with a black granu- 

 lar pigment in its excretory apparatus and body parenchjmia. It 

 caused little or no symptoms in human beings, and was found acci- 

 dentally in post-mortems. 



2. Distoma hepatis endemicum sive perniciosum, which was smaller, 

 8 to II millimetres in length, and did not possess the above char- 

 acters, while its eggs were only 20 to 30 p in length by 15 to 17 in 

 breadth. 



Kobayashi finds that Looss's differences between C. sinensis and 

 C. endemicus do not hold good. They were (i) size ; (2) discontinuity 

 of the vitellaria ; (3) pigmentation; (4) size and shape of the egg. 

 In the experimentally reared forms there are no such constant 

 differences. 



It is found in Japan, where it is common, and in Annam and 

 Tonkin, in man, cats, dogs, and pigs. 



Morphology. — Clonorchis sinensis is a white, or yellowish-red, or brownish, 

 narrow trematode, 13 to 19 millimetres in length and 3 to 4 millimetres in 

 breadth. The pigmentation is due to the deposit of fine yellowish or brown 

 granules in the body parenchyma. The ramifications of the testes are long, 

 the anterior arising from four and the posterior from five main stems, with 

 sometimes ventral bulgings. The ovary is trilobate, but may show three to 

 six smaller lobules. The yolk glands reach from the ventral sucker to the 

 level of the ovary, and are peculiar in that certain groups of follicles remain 

 undeveloped. In perfectly mature specimens the seminal vesicle extends back 

 as far as the middle of the uterus. The eggs are generally narrowed towards 

 the anterior end, and have a rather high lid, with a sharply projecting brim 

 (these peculiarities may be absent.) The egg is 29 [jl in length and 16 ^ in 

 breadth. 



Life-History.^ — ^Kobayashi has found the cysts in the muscles of 

 fish — Pseudorasbora parva, Leucogobio guntheri, Leucogobio mayedce, 

 and Carassius auratus — and was able to infect cats by feeding with 

 the infected flesh. He also found cysts in other fish — Acheilogna- 

 thus lanceolatus, A. limbatus, A. cyanostigmus , Paracheilognathus 

 rhombeus, Pseudoperclampus typus, Abbottina psegma, Biwia zezera, 

 and Sarcocherlichthys variegatus. These fish are the second inter- 



