Page:Tropical Diseases.djvu/857

Rh more attenuated anteriorly than posteriorly. It measures from 9 to 12 mm. in length by 2.5 mm. in breadth. The oral sucker (Fig. 163, m) is terminal and larger than the acetabulum or ventral sucker (Fig. 163, ac), which is situated close to it, just below the bifurcation of the intestine. The cuticle is densely covered with spines. The pharynx (Fig. 163, pb) is large and globular; the intestinal cæca extend to about the posterior eighth of the body. The testes (Fig. 163, t,t) are in the posterior third and somewhat apart. The anterior one is roundish, the posterior one lobate. The ovary (Fig. 163,ov) is placed at about the middle of the body. The uterus (Fig. 163, ut) appears to be poorly developed, its convolutions spreading laterally barely beyond the cæca. The vitellaria (Fig. 163, vt) appear to extend from acetabulum to posterior testicle. The eggs are oval and measure 34 μ by 19 to 21 μ. Pathogenesis.— Only a very few cases have been reported. In two, described by MacConnell, the parasites were found in large numbers in the bileducts, which were thickened and sacculated.

Synonyms.— Distoma sinense; D. spathulatum; D. japonicum; D. innocuum; Opisthorchis sinensis; Clonorchis endemicus. History.— Clonorchis sinensis was discovered almost simultaneously by MacConnell in India and MacGregor in Mauritius, in 1874.

Geographical distribution— It has been found in many Eastern countries, including India, Mauritius, Japan, Korea, Formosa, China and Tonkin. In the last-named country it appears to be very common. In Central Japan, according to Katsurada, there are certain districts in which it affects from 56 to 67 per cent, of the population.

The parasite.— {{smaller|C, sinensis (Fig. 164) measures from 10 to 20 mm. in length, by 2 to 5 mm. in breadth; it is oblong, narrow, flat and somewhat pointed anteriorly, reddish in colour, and nearly transparent. The oral sucker is larger than the ventral acetabulum, which is situated almost on the border between the first and second fourths of the body. The cuticle has no spines. The pharynx is globular and short (Fig. 164, pb}, the œsophagus is slender and 0.17 mm. long. The bifurcation of the intestine is nearer to the oral than to the ventral sucker. The intestinal cæca are simple, slender, and extend almost to the posterior end of the body. The genital pore opens on the middle line immediately in front}}