Opisthorchis viverrini

Name

Greek: opisthen = behind; orchis = testicle. Latin: viverrinus = civet cat-like; thus the name is closely related to the position of the male sexual organs inside the worm and to one of the main final hosts. English: Civet cat worm.

Geographic Distribution/Epidemiology

These worms occur in Thailand, focally in Laos, Vietnam, Cambodia, Japan, and India. About 20–30 millions of humans are estimated to be infected.

Morphology/Life Cycle

The adult translucent worms measure about 7–9 × 3–4 mm and can be morphologically differentiated at one side from Clonorchis by their testes (Fig. 1), which appear deeper lobulated than those of Opisthorchis felineus. In contrast to C. sinensis, there are always only four branches of each of the two testes. The life cycle runs similarly to that of Clonorchis sinensis.

Opisthorchis viverrini, Fig. 1

Light micrograph of an adult translucent worm of Opisthorchis viverrini. Note the two lobulated testes in the posterior region, the laterally situated...