Liver Fluke

The liver fluke, Fasciola hepatica, is a highly pathogenic flatworm parasite of ruminants, mainly sheep and cattle. It causes severe liver damage, especially in sheep and can result in the sudden death of previously healthy animals. The disease is also responsible for considerable economic losses, estimated at ~£50m in Scotland alone, due to direct production losses, poor reproductive performance and livers condemned at slaughter. The disease appears to be on the increase in the UK and spreading into previously fluke-free areas, possibly as a result of recent climate change (milder winters and wetter summers) favouring the parasite and its mud snail intermediate host.

Control of fluke has historically involved the strategic application of flukicidal drugs, however, this approach is not thought to be sustainable in the face of increasing reports of flukicide resistance. Diagnosis of fluke is also not straightforward. Faecal egg counting is not a reliable indicator of infection and immunological tests do not discriminate between current and previous infections. Also, there is no vaccine available against fluke.

Here at Moredun, we have recently initiated research aimed at:

• Improving diagnosis of active fluke infection in the host animal through an evaluation of existing blood and faecal fluke ELISA tests
• Determining the efficacy of flukicidal treatment as a measure of emerging resistance
• Monitoring fluke infection levels on farm as a predictor of disease risk, by measuring intermediate host snail abundance and fluke infection levels over the grazing season
• Identifying novel vaccine targets on the surface of the fluke gut – this approach has been particularly successful against blood-feeding parasites such as Haemonchus contortus; F.hepatica is also a blood-feeder

Dr Philip Skuce spoke to Landward about fluke in an edition of the popular farming and countryside programme broadcast on BBC Scotland on 12th April 2013: