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Department Issue Liver Fluke Forecast and Alert

Liver Fluke Forecast

A liver fluke disease-forecasting model based on data provided by Met Eireann with regard to  weather conditions last winter and rainfall during the summer and early autumn of this year predicts that the risk of liver fluke infestation is very high in all areas including parts of the country not usually considered at risk such as the east and south east of Ireland. The high summer rainfall and mild wet winter weather provided conditions suitable for the over-wintering and propagation of the snail intermediate host, as well as the production of the infective stage of the liver fluke on all types of pasture.

Significant Surge in Acute Liver Fluke Disease - Regional Veterinary Laboratories

There has been a significant surge in the numbers of sheep carcasses submitted for post mortem to the Dept of Agriculture, Food & the Marine's Regional Veterinary Laboratories that are severely affected with acute liver fluke disease. Several of the recent outbreaks resulted in multiple deaths.  In many of these cases, the animals have been treated but treatment has been either too late or farmers have used an inappropriate product.

Acute liver fluke disease is caused by immature liver flukes (not adults) and is difficult to confirm in live animals, as there are no eggs to detect in a dung sample.  Sheep are more susceptible than cattle, but a heavy fluke challenge can affect growth rates and body condition in cattle too.   If acute liver fluke disease is suspected or confirmed, then it is essential that flukicides that are effective against immature liver fluke are used.  Products that only kill adult liver fluke should be avoided.  These flukicides are short acting (although residues are detectable in meat and milk for a period after treatment).  Animals treated this week may need to be re-treated again in 4-6 weeks time if animals are on fluke infested pasture, and some low-lying poorly drained pasture has such a high liver fluke challenge that sheep should not be grazed on it at all this autumn/winter if there is an alternative.

Livestock owners should review their fluke control programmes in the light of this year's acute liver fluke threat, ideally in consultation with their veterinary surgeon.  As the months go by the threat from acute fluke disease will recede and farmers will need to be aware of sub-acute & chronic disease which will inevitably follow.  In previous years where disease was as widespread and severe as is being reported currently, there were significant problems with weak ewes, stillbirths and ewes having insufficient milk to rear lambs because of heavy fluke burdens, so early and appropriate intervention and ongoing fluke control is very important this year.

Rumen fluke is a separate parasite; the immature stages cause diarrhoea and death. The drug that is usually used to control them kills adult liver fluke only and is not indicated for treatment of immature liver fluke, therefore control of these two parasites should be considered and addressed separately.

Further detail on Liver Fluke and its control and information on flukicide selection is available in Animal Health Ireland's leaflet 'Liver Fluke - the facts', which is on AHI's website at:

Date Released: 26 October 2012