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Unprecedented Parasite Threat to UK Livestock in next 60 Years – SAC Research Warns Liver Fluke Spread with Climate Change

SAC News Release Ref. No: 11N11
Published: 26 Jan 2011

Liver Fluke Cycle (opens in new window)

New work by SAC (Scottish Agricultural College) researchers and collaborators at University of York, predicts unprecedented outbreaks of Liver Fluke in the UK over the next 60 years.

By combining tried and tested annual disease forecasting techniques with climate change projections the SAC work indicates that by 2020 serious epidemics of the parasite amongst cattle and sheep in Scotland could be the norm, with very severe epidemics in Wales by 2050. Much of western England will also be affected. SAC Researchers argue this new information should be used to help target resources for disease surveillance and control.

While of no risk to the human food chain, the small flat liver fluke parasites cause cattle or sheep to lose condition and, sometimes, suddenly die. The life cycle of fluke (Fasciola hepatica) includes time spent in a pond snail (Lymnaea truncatula) where it multiplies. The snail thrives in wet, poorly drained pastures. When the fluke larvae leave the snail they swim onto vegetation and form cysts so stock are infected as they graze. The parasite then migrates to the animal’s liver where it damages tissue. Depending on the fluke infestation stock can be unthrifty or die while the parasite activity also lowers resistance to other diseases.

SAC experts are well used to forecasting the likely level of Fluke risk each new year and recommending to farmers how best to avoid the worst effects through appropriate management and treatments. For the first time this new work by SAC uses UK climate change models to help predict where and when the conditions favouring the fluke and its host snail are likely to occur far further into the future.

While the overall risk in the UK will rise it will be far greater in areas where rainfall and winter temperatures are predicted to increase, suiting both parasite and host (Liver Fluke needs temperatures above 10 degrees C). In simple terms this means the west coast of Britain and western Wales in particular. In addition the milder winters will increase the survival of larvae and extend the problem from a seasonal to an all year round threat. 

Naomi Fox, who carried out the work for her PhD, said “I was surprised to see that by 2050 Wales will overtake Scotland as being at most risk from serious fluke epidemics”.

Naomi also points out that her work involved dividing the country into 25 kilometre squares and averaging the information. It is likely that if a “square” as a high average individual farms within it could suffer exceptionally high outbreaks.  In eastern areas or parts of SW England, where summer temperatures will be higher and rainfall declines there could be a far lower incidence. However certain areas of SW England could see local rises.     

SAC believe these results are an early warning about new developments of a well understood problem. They will alert the industry and authorities to the potential threat and help with forward planning. While successful treatments exist flukes can develop resistance to the medicines if they are over used or used at the wrong time in the fluke’s life cycle. In the light of the new predictions the livestock sector will need to review the approach to the control and medication of liver fluke cases 

For those wanting more information then work has been published in the open access journal PLoS One.

Naomi Fox can be reached on 07719 207 031. Team Leader SAC Disease Systems Research, Dr Mike Hutchings 0131 535 3231. Brian Hosie, Group Manager SAC Consulting Veterinary Services, 0131 535 3140.

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News Release Issued By

Mr Ken Rundle
Senior Communications Officer
SAC (Scottish Agricultural College) Work SAC, King's Buildings, West Mains Road,
Edinburgh
EH9 3JG
TelWork 0131 535 4196

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