Lamb liver fluke antibody test results - Nov 2020
Using abattoir blood samples from slaughtered lambs to detect the timing & spread of fluke infection
Since 2015, from June to December, DAFM has taken lamb blood samples in factories from a proportion of flocks at the time of slaughter. These have been tested for liver fluke antibodies to determine the timing and geographical spread of liver fluke challenge to grazing lambs. This testing did not commence until August in 2020, due to challenges caused by the COVID pandemic in slaughter plants.
The number of flocks selected for sampling from each county is intended to be proportionate to the sheep population of that county over the entire sampling period (August to November 2020). A number of samples are taken from each selected flock, and these are pooled at laboratory level. The presence of liver fluke antibodies reflects the level of challenge the lambs have experienced during the most recent grazing season. The presence of liver fluke antibodies in 2020 born lambs is therefore a sentinel for exposure to liver fluke in the wider sheep population in the region, as by definition these lambs must have been exposed during the 2020 grazing season.
Results up to and including November 2020
Results for the country for August to November 2020 are as follows:
Please see maps in Figure 1 and Figure 2 below for more detail on the distribution of positive and negative results.
Map 1 Liver Fluke Nov 2020 (pdf 139Kb)
Figure 1: Lamb liver fluke ELISA test results for November 2020. Points have been moved slightly to preserve anonymity of flock owners.
Map 2 Non-negative fluke ELISA results up to Nov 2020 (pdf 142Kb)
Figure 2: Non-negative lamb liver fluke ELISA test results up to November 2020. Points have been moved slightly to preserve anonymity of flock owners. Closed points refer to positives for November; open points refer to positive results from the previous months.
In the November testing, certain areas appear to show high levels of liver fluke exposure. Positive test results were detected in substantial numbers in flocks based in the west and northwest. Continuing a pattern seen in the previous month, substantial numbers of positive and inconclusive results were also found in other areas, including Cork, the border and midlands areas, and parts of Leinster.
These results are consistent with DAFM’s liver fluke forecast produced in November 2020, which predicts that cattle and sheep in most areas of the country are at substantial risk of liver fluke this winter. The forecast is available at: https://www.gov.ie/en/publication/5e62b-liver-fluke-forecast-november-2020/
As the sample size for some counties is small, farmers in these particular counties need to be cautious when interpreting the results of the survey as they relate to their areas. Additionally the county associated with a batch of lambs is that where the flock of submission is registered. In a minority of cases, where the lambs had been purchased shortly before slaughter, the county associated with a batch will not reflect accurately where the batch of lambs spent its life. Absence of inconclusive or positive test results for a particular county should not be taken as conclusive evidence that liver fluke is absent from that county.
Thanks to Seamus Fagan of Athlone Regional Veterinary Laboratory, Padraig Kellegher of VPHIS and Kate O’Keeffe, DAFM blood testing laboratory in Cork for the information provided.