80 I'ltKSIUEXTIAL AI)I)nB:SS SECTIOX D. 



Christophorson ixi Khartoum, and has since been successfully 

 practised in almost all areas where bilharziasis is endemic. 



Cloxouchiasis. 



The Chinese liver fluke, Clo)iorchis sinensis, has been known 

 as a parasite of man since 1875, when the adult form was 

 <lescribed by Cobbold. The life-history of the worm has, however, 

 only been elucidated relatively recently by the experimental work 

 of several Japanese scientists. Clonorchiasis is known to occur 

 in China, Formosa and Japan, and cases have been reported in 

 Chinese subjects from many parts of the world. Eecently (May, 

 1922) a case occurred in Johannesburg.* 



The adult fluke varies from 10mm. to I7mm. long, and is about 3mm. 

 broad. It is thin and delicate looking, and is found in the liver and gall 

 bladder of man, and also of cats, dogs, pigs and rats in the East. Some 

 interesting points in its morphology may be mentioned. The body con- 

 tains numerous densely-packed yellowish-brown granules, which, according 

 to Kobayashi, are derived from the yolk. The simple intestine forks just 

 below the oral sucker, the ca?ca extending almost to the posterior end 

 of the body. There is a large S-shaped excretory bladder dorsal to the 

 testes. Its two main contribiitory channels originate near the point of 

 forking of the intestine and open into the bladder near its anterior end. 

 The excretory pore is median and terminal. 



The anterior testis usually has four branches, and the posterior testis 

 five. The ovary usually has three large and one small lobe. The vitellaria 

 or yolk glands are situated laterally, and extend from the ventral sucker 

 nearly to the posterior end of the body. They may or may not be dis- 

 continuous, this depending on the age and stage of growth of the parasite. 



The ova are about 24^ to SOn long, and are about ISn broad. The 

 operculum is very distinct, and has been compared with the lid of a teapot. 



The life-history of Clonorchis is of considerable interest. The 

 immediate source of infection of the higher vertebrates such as 

 man, dog and cat, was worked out by Kobayashif in 1911. He 

 found that certain freshwater fishes belonging to the Cyprinidae 

 {carp and roach family) acted as second intermediate hosts, 

 harbouring encysted cercarise on their gills and in their livers and 

 musculature. By administering such cj^sts in raw fish to normal, 

 healthy kittens, adult Clonorchis were produced. The principal 

 infected fish were Pseudomsbora parva, Leucogohio gnntheri, 

 Lcucogohio mayedae and Carassius auratus. Other fish infected 

 to a lesser extent were Acheilognathus lanceolatus, A. limbata, 

 A. cyanostigtna, ParacheilognatJius rho^nbus, Pseudoperilaminis 

 typus, Abbottina pscgmn, Buivia zczcra, and Sarcocheilichthyf> 

 variegatiis. The Clonorchis cysts are oval, the largest being about 

 135^, to 145u. by 90|.i to lOOfi. The larva within is bent on 

 itself, and at an early stage of encystment still has ej^espots. In 

 n fairly old cj^st, rudiments of all the adult organs can be 

 detected, while the ventral sucker is more pronounced than the 

 •oral, but this relation is reversed in the adult condition. Young 

 ■encysted flukes have spines in their cuticle, and these grow larger 

 when the young fluke emerges from its cyst in its final host. 

 Gradually, however, the spines are lost, and specimens obtained 

 from experimental cats 23 days after the infective feed are the 

 ■oldest known to possess spines. 



* See Medical Jmnnnl of Smith Africa, xvii, pp. 240 — 244. 



"f For accounts of Japanese literature see reviews in the Tropical Dixcases 



Brill ct ill and in the China Medical Joujiial. 



