26th November 2021

COWS has uploaded a video of the different stages of the liver fluke parasite from egg-laying adult to egg-laying adult.

Moving images prove to be much more powerful than any Life Cycle drawn on a piece of paper, and really hit home how fascinating and potentially pervasive these parasites are.

See the video here

This piece of work has taken many years and has been produced by parasitologist Dr Clive Bennett, working with cameraman David Barlow. The live liver fluke stages were provided by Ridgeway Research Ltd.

Fasciola adults are flat worms that live in the bile ducts of cattle and sheep. To hold their position and move they use suckers and spines. Eggs are produced in their millions passing through the gut and onto pasture in faeces to reach water.

Miracidia develop in the eggs to hatch after two weeks. The miracidia are attracted to mud snails that live and breed on the pastureland to infect young snails. The miracidia attach and shed their outer layer. Once inside, miracidia become sporocysts. One sporocyst can produce up to 4000 cercariae. The cercariae emerge from the snails and swim vigorously until they find a surface to which they can attach forming a cyst and shedding their tail.

Cysts on pasture await ingestion by a mammalian host. Digestion in the gut releases a metacercarial cyst and activates the juvenile fluke inside to excyst!

The juvenile uses its suckers and spine to work its way through the gut and liver to the bile duct and complete the life cycle releasing more eggs…