The Department of Agriculture, Food and the Marine (DAFM) has issued a map outlining the predicted risk of disease caused by liver fluke (Fasciola hepatica) infection in livestock this winter.

This year’s forecast is based on meteorological data gathered between May and October 2025 by Met Éireann.

The information has been provided to farmers by the department, in collaboration with Met Éireann, University College Dublin (UCD), Teagasc and Animal Health Ireland (AHI).

Liver fluke

The data predicts infection being most prevalent in the midlands, west and northern half of the country, with a lower disease prevalence in the south-east.

The low values of the summer index in the east are due to the dry conditions in June and September 2025.

The map below includes the Ollerenshaw Summer Index values for 2025, and the risk of disease due to liver fluke:

The Beef HealthCheck programme, run in partnership with Meat Industry Ireland (MII) and meat factories nationwide, collects and reports liver fluke information in cattle at slaughter from participating abattoirs.

While there was an increase in liver fluke in 2024 for the first time in years, 2025 has returned to previous levels.

To date this year, abattoir examinations showed an average of 34% of herds with at least one animal with liver fluke damage.

Beef HealthCheck

The programme data also shows that active infection in one or more animals was seen in 12% of herds, compared to 17% last year.

Counties in the north-west of Ireland were more heavily affected, with 60-80% of herds in counties Sligo; Mayo; Leitrim; Roscommon; and Donegal reported to have signs at slaughter.

The prevalence within herds is typically low, depending on the farm with 6% of animals presented to slaughter showing signs of liver fluke damage and 1.2% of animals showing the live parasites.

DAFM

DAFM said that it is important for farmers to know whether liver fluke is present on their farm and to treat accordingly to avoid production losses.

The department advised that to assess the risk of liver fluke disease on any particular farm, various environmental factors, particularly climate, landform, and soil type must be taken into account.

This is because the intermediate host of the parasite, which is a mud snail (Galba truncatula), occurs in soil that is slightly acidic and muddy.

Therefore areas with rushes or wet patches (e.g., around gates and troughs) are particularly important with regard to liver fluke risk as they can help to maintain a population of the infective stage of the parasite.

In addition, livestock owners should factor in prior liver fluke history on the farm as this is an important indicator of future disease risks.

Liver fluke infection tends to be chronic in cattle, resulting in ill-thrift and poor performance.

In areas of high risk and on farms where liver fluke infection has been diagnosed or where there is a prior history, livestock owners should consult with their vet to devise an appropriate control programme.