Asian liver fluke infection

Clonorchis sinensis

Clonorchiasis is due to an infection with the small liver fluke Clonorchis sinensis (Opisthorchis sinensis). Adult flukes (with a length of up to 2.5 cm) inhabit the distal bile ducts.

The fully developed eggs are passed with the faeces. For further development of the miracidium, eggs have to be eaten by the first intermediate host, a water snail. In the first intermediate host, thousands of cercariae are produced which have to find the secondary intermediate host where they encyst in the superficial tissue and become metacercariae. Fish-eating animals and humans become infected by eating raw fish. The prepatent period – from infection until first eggs are found in the faeces – is about a month. To complete this, life cycles within three hosts needs at least 3 months.