Warm and wet weather conditions this year have contributed to over one third of the cattle herds in Ireland having at least one animal with liver damage due to fluke.
This information comes from the Beef HealthCheck programme, which is run in partnership with Meat Industry Ireland (MII), that collects and reports liver fluke information in cattle at slaughter from participating meat factories nationwide.
To date, abattoir examinations showed an average of 39% of herds with at least one animal with liver damage due to liver fluke and live liver fluke parasites were seen in 12% of herds.
Overall, the Department of Agriculture, Food and the Marine (DAFM) has said this year’s levels of liver fluke infection are slightly lower than those reported in the last few years.
However, the consistently high rainfall this year could result in a higher risk of liver fluke on certain farms going into winter.
Fluke forecast
Each year, the DAFM in collaboration with Met Éireann, University College Dublin (UCD), Teagasc and Animal Health Ireland (AHI) advises farmers of the predicted risk of disease caused by liver fluke infection in livestock for that winter.
This year’s forecast is based on meteorological data gathered between May and October 2023 by Met Éireann.
The Ollerenshaw Summer Index 2023 predicts infection being prevalent across all areas of Ireland with the exception of south Leinster where the risk of disease is somewhat lower.
The high values of the index are due to the warm, wet conditions experienced in July, August, September and October.
Counties in the north-west of Ireland were more heavily affected, with 70-80% of herds in Counties Sligo, Roscommon and Donegal reported to have signs of liver fluke at slaughter.
The prevalence within herds is typically low depending on the farm with 6.6% of animals presented to slaughter showing signs of liver fluke damage and 1.1% of animals showing live liver fluke parasites.
It is important for farmers to know whether liver fluke is present on their farm and to treat accordingly to avoid production losses.
Liver fluke in sheep
From June to December, DAFM collects blood samples from lambs in meat factories from a proportion of flocks at the time of slaughter.
These are tested for the presence of liver fluke antibodies to determine the timing and geographical spread of liver fluke exposure in grazing lambs.
The number of flocks selected for sampling from each county is generally proportionate to the sheep population of that county over the entire sampling period.
Data from this survey indicates that the majority of infected flocks reside in counties in the west.
Some positive and inconclusive results were reported in counties outside of the west and the north-west in the August testing, possibly associated with a high summer rainfall level.
This was the case in the border areas, midlands, south and in Leinster where there was substantial evidence of fluke exposure in lambs by October.
From July to October 2023, blood samples from 757 flocks across 26 counties were tested for the presence of liver fluke antibodies.
Month No. Flocks Tested No. ELISA Positive Positive (%) July 268 16 6 August 176 25 14.2 September 179 51 28.5 October 134 19 14
The presence of liver fluke antibodies in 2023-born lambs shows the exposure to liver fluke in the wider sheep population in the region, as these lambs must have been exposed during the 2023 grazing season.