Quality Monitoring of Liver Fluke Metacercariae

At our laboratory part of the work we do is to maintain several colonies of mud snails. These are intermediate hosts in the life cycle of the liver fluke, Fasciola hepatica. After eggs pass out of infected sheep in faecal matter, the eggs remain dormant on pasture until conditions are optimal. When weather conditions are warm and wet, the eggs hatch into the free-living stage. These miracidium actively seek out the snail hosts and subsequently infect them. Once inside the snail, the fluke undergo several stages of development and multiplication until they form infective metacercariae. These emerge from the snail when conditions are favourable.

Our snail colonies are carefully managed to not only to keep them healthy, but to provide the maximum possible metacercariae. The metacercariae we produce are supplied to universities and pharmaceutical companies. They are then used in research to gain a better understanding of the parasite. They are also used in researching its control and the growing problem of liver fluke resistance to anthelmintic treatments.


We ensure the metacercariae we supply to our customers are the best they can be. To do this, we clean them regularly, monitor their quality and select only the viable healthy cysts before dispatch. Below are images that show the difference between a viable and in comparison, an unviable cyst.

Additionally, we try to supply the youngest cysts whenever possible. We will only supply metacercariae that are less than 4 months old, to ensure viability. We carried out a storage test using our triclabendazole-susceptible Italian strain of liver fluke, see Graph 1. This clearly demonstrates that there is a sharp and steep decline in the viability of the cysts after 6 months of storage.

After 4 months the viability of the metacercariae cysts decreased by 6.5%, at 6 months by 18.2% and subsequently after 12 months by 96.3%. Graph 2 shows these data.

If you are planning or conducting research into live fluke, contact us here. If you’d like to order some of our metacercariae, please order here. Moreover, we’d love to hear from you if you’ve used our metas in your research!