The Impacts of Climate Change on Liver Fluke in the UK
Scientists in the UK predict liver fluke infection will reach unprecedented levels’ during the next 60 years as climate change takes its toll.The apparent increase in liver fluke risk to cattle and sheep is climate driven and the problem is set to get much worse. So say scientists in Edinburgh and York, who have been studying risk maps from a 36-year period – 1970 to 2006. The increases shown in these risk maps is consistent with empirical data and the researchers also predict that the UK will experience unprecedented levels of infection during the next 60 years, with serious epidemics expected to be the norm by 2020 in parts of Scotland, and by 2050 in parts of Wales.
“With some parts of the UK experiencing risk from overwintering larvae, liver fluke infection could extend from being a seasonal to a year-round threat,” said the Scottish Agricultural College’s Naomi Fox.
“Our forecast is the first approximation of the potential changes in fascioliasis risk in the UK, and indicates where active disease surveillance should be targeted,” she added.
Fasciola hepatica (liver fluke) is a physically and economically devastating parasitic trematode whose rise in recent years has been attributed to climate change. The National Animal Disease Information Service currently provide sheep and cattle producers with short-term fascioliasis risk based on the Ollerenshaw index – a model driven by the influence of rainfall and temperature on the free living stages of the parasite and its intermediate host, the dwarf pond snail.
The researchers combined the Ollerenshaw index with long-term past climate data to demonstrate how climate has driven the change in fascioliasis risk to date. “We then use the UK met office climate projections to determine the potential impacts of climate change on future fascioliasis risk in the UK,” explained Miss Fox.
“Throughout the UK, the average liver fluke risk from summer infection has increased during the past four decades, but there has been little risk from overwintering larvae.
“The future risk maps that we drew up illustrate that, for the summer, risk is predicted to generally increase further, with serious epidemics predicted in Scotland by 2020 and Wales by 2050.
“Additionally a steady increase in risk from winter infections is forecast along the West Coast with Wales being most at risk. The mean fascioliasis risk in each season will be higher in the future than the past for all regions of the UK, with the highest overall risk being in Wales.”
Miss Fox added, however, that there would be periods of widespread decrease in risk and localised areas of long-term risk reduction.
Full details: Fox NJ, White PCL, McClean CJ, Marion G, Evans A and Hutchings MR: “The impacts of climate change on Fasciola hepatica risk in the UK.”
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August 2012