Liver fluke (Fasciola hepatica) remains one of the most significant parasitic challenges for sheep and cattle farmers across the UK. It has an impact on livestock health, productivity, and farm profitability. Understanding the parasite’s

lifecycle, risks, and control strategies is key to protecting your animals.

The Parasite and Its Lifecycle. Liver fluke is a flatworm that infects the livers of grazing animals. Its lifecycle depends on a tiny mud snail (Galba truncatula), which acts as an intermediate host. Eggs shed in dung develop into larvae that infect snails, then emerge as infective stages that attach to grass. Once ingested, these larvae migrate from the guts, through the abdomen and then penetrate the liver, causing tissue damage before maturing in the bile ducts.

• This complex lifecycle explains why fluke problems are highly influenced by weather. Mild, wet conditions increase snail numbers and extend the risk period for infection, while drier summers tend to reduce pressure we need to remember that the only place that grass will grow is in bogs and ditches.
• Climate variability means farmers cannot rely on old patterns—fluke can now appear outside the traditional autumn and winter windows.