Lamb liver fluke antibody test results Nov 2019
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 (Fasciola hepatica) antibodies to determine the timing and geographical spread of the onset of liver fluke challenge to grazing lambs.
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 (June to November 2019). 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 degree of fluke challenge the lambs have experienced during the most recent grazing season. The presence of liver fluke antibodies in 2019-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 2019 grazing season.
Results up to and including October 2019
Results for the country, for October 2019, and for the year up to and including October 2019, are as follows:
Please see maps in Figure 1 and Figure 2 below for more detail on the distribution of positive and negative results. Points have been moved slightly to preserve the anonymity of flockowners.
Fluke Exposure October 2019
Figure 1: Lamb liver fluke ELISA test results for October 2019.
Fluke exposure up to and including October 2019
Figure 2: Non-negative lamb liver fluke results for the year up to and including October 2019. October results are represented by closed (filled) points; previous non-negative results are represented by open points.
The percentage of samples testing either inconclusive or positive was substantially higher in October compared to previous months. As was the case in previous months, positive results were recorded for numerous flocks located near the west coast. A substantial number of positive test results was recorded in the midlands and north Leinster for the first time. The maps continue to suggest a gradual expansion of the area where liver fluke is active as the year goes by. Please see Figures 1 and 2 above.
As can be seen from Figure 1 above, some parts of the country were represented on the October survey by a relatively small number of flocks. Accordingly, farmers should exercise caution when interpreting the results of the October survey as they relate to local areas. 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. This should also be borne in mind when interpreting the results.
Thanks to Seamus Fagan of Athlone Regional Veterinary Laboratory, Charlie O’Connell of VPHIS and Kate O’Keeffe, DAFM blood testing laboratory in Cork for the information provided.