Opisthorchis And Clonorchis

Opisthorchiasis and clonorchiasis are caused by biliary flukes and are estimated to infect over 30 million people worldwide (Hopkins, 1992). Acquired by the ingestion of meta-cercariae from raw fish, these organisms are endemic in China and South-east Asia. Chlonorchis sinensis was discovered in Calcutta in 1875 by McConnel and was originally named Distomum spathulatum (Komiya, 1966). In 1895, Blanchard named the genus Opisthorchis and placed Distomum sinense in it. Looss later created the genus Clonorchis in 1907 and distinguished it from Opisthorchis by the presence of branched instead of lobed testes. Although considered a member of the genus Opisthorchis, the name C. sinensis persists due to its long tradition of use. The life-cycle and clinical features of C. sinensis, O. viverrini and O. felineus are similar and will be described together.

Principles and Practice of Clinical Parasitology

Edited by Stephen Gillespie and Richard D. Pearson © 2001 John Wiley & Sons Ltd

Fig. 17.1 Life-cycles of Opisthorchis, Clonorchis, Fasciola hepatica and Paragonimus spp. Life-cycle stages not drawn to scale. Illustrated by David W. Ehlert, MAMS

Fig. 17.2 (A) Clonorchis sinensis adult (~10x3mm). (B) Opisthorchis viverrini, adult (~10x3mm). (C) O. viverrini egg (~26 x 15 |im). C. sinensis adult distinguished from O. viverrini by branched vs. lobed testes. While C. sinensis eggs are similar to O. viverrini eggs, the former also have a terminal knob and a shoulder around the operculum. Eggs photographed at same magnification in Figures 17.2-17.4. Reproduced by courtesy of Professor Prayong Radomyos, Faculty of Allied Health Sciences, Thammasat University, Thailand

Fig. 17.2 (A) Clonorchis sinensis adult (~10x3mm). (B) Opisthorchis viverrini, adult (~10x3mm). (C) O. viverrini egg (~26 x 15 |im). C. sinensis adult distinguished from O. viverrini by branched vs. lobed testes. While C. sinensis eggs are similar to O. viverrini eggs, the former also have a terminal knob and a shoulder around the operculum. Eggs photographed at same magnification in Figures 17.2-17.4. Reproduced by courtesy of Professor Prayong Radomyos, Faculty of Allied Health Sciences, Thammasat University, Thailand

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