Department warns of high risk of liver fluke infection on livestock farms

The Department of Agriculture has warned that the risk of disease due to liver fluke infection is high for most parts of the country.

In isolated areas of the east and southeast there is a risk of occasional losses in untreated animals.

This latest liver fluke forecast is based on meteorological data provided by Met Eireann with regard to weather conditions last winter and rainfall during the summer and early autumn of this year.

Liver Fluke survey

Blood samples collected by Department staff from a semi-random selection of lambs born in 2016 across 24 counties were tested for liver fluke antibodies by the Regional Veterinary Laboratories (RVLs) to determine their level of exposure.

The number of samples tested in 2016, when compared to 2015 figures, showing moderate to heavy challenge with liver fluke has increased by 22 and 24%, respectively.

These moderately and heavily infected lambs were from the midlands and west of the country, according to the Department.

Animal Health Ireland

Further to the disease forecast, preliminary information from the Animal Health Ireland Beef HealthCheck programme suggests that nationally the frequency of fluke damaged livers in cattle at slaughter has increased slightly over the summer months and into the autumn.

It found that live fluke was detected at low but consistent levels through this period. The frequency of these findings is greatest in cattle going to slaughter from north western and western counties.

The Beef HealthCheck programme now provides a high level of coverage of cattle nationally, and work is ongoing to analyse the information it provides.

Farm-to-Farm Variation

In assessing the risk of liver fluke disease on any particular farm, variation between individual farms in their soil type (whether soils are heavy or free-draining) must be taken into account, in addition to weather, according to the Department.

The intermediate host, which is the mud snail, tends to be located in slightly acidic and muddy conditions.

Thus, areas of fields with rushes are a particularly common location where mud snails can be found. Aside from local conditions on the farm and prior weather conditions, the Department advises that it is important that livestock owners also factor in prior liver fluke history on the farm.

Monitoring of Disease

Liver fluke infection tends to be chronic in cattle, resulting in ill thrift and poor performance and similarly in sheep, chronic disease can occur.

However, infection in sheep can also result in sudden death in cases of heavy challenge.

Livestock owners are being reminded to remain to be vigilant for any sign of illness, ill thrift or mortality in their stock and should consult with their veterinary practitioner for diagnosis of liver fluke infection or other potential causes of these clinical signs.

It is recommended to submit carcasses to a RVL for post mortem examination in cases where the cause of death is not obvious.

Information from abattoir examination of livers (Beef HealthCheck reports for cattle) of previously sold fattened stock is also a valuable source of information to inform livestock owners of the incidence of liver fluke infection on their own farm or on the efficacy of their control program.

Treatment and Control

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

With regard to dosing, livestock owners should factor in the time of year when doses are being given.

For example, when treating in the autumn or early winter, treatment should be directed at all stages of the liver fluke (early, immature and mature stages).

Later in the winter when animals are housed, treatment can be more directed towards mature stages.

Therefore, it is important that product choice to match the stage of development of liver fluke is considered when choosing a flukicide, the Department advises.

Advice should be sought on the need (if any) for re-treatment and the appropriate interval at which such treatments should be given – This is especially important given that resistance to flukicides is becoming an increasing concern.

Where it is feasible, and as a long-term control option, areas of fields which are suitable habitats for the intermediate host (wet muddy areas often containing clumps of rushes) should be either fenced off or drained, which will result in a permanent reduction of snail habitat.

What about Rumen Fluke?

There have been significant, but as of yet isolated incidents, where immature rumen fluke has been diagnosed as the principal cause of mortality in both cattle and sheep on both the east and west coast in the last six weeks.

According to the Department, livestock owners should seek advice from their veterinary practitioner before embarking on potentially needless treatments.

Before embarking on potentially needless treatments, it is important that livestock owners seek advice from their veterinary practitioner and all cases of scouring or sudden deaths in cattle and sheep should be fully investigated.

The finding of rumen fluke eggs alone in faecal samples is not reason enough to warrant treatment of animals, it advises.

Further Information Source

Further detail on liver fluke and its control and information on flukicide selection along with further information on the Beef HealthCheck programme is available online.