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Lamb liver fluke antibody test results Dec 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 November 2019

Results for the country, for November 2019, and for the year up to and including November 2019, are as follows:

 Added 10.01.2020

 

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 flock-owners.

 

 Fluke Exposure November 2019

Added 10.01.2020

 Figure 1: Lamb liver fluke ELISA test results for November 2019.

 

 Fluke Exposure up to and including November 2019

Added 10.01.2020

Figure 2: Non-negative lamb liver fluke serology results for the year up to and including November 2019. November results are represented by closed (filled) dots; previous non-negative results are represented by open dots. 

 

The percentage of samples testing either inconclusive or positive reached the highest levels for the year so far during November. This is not surprising given the yearly pattern in fluke occurrence (with a peak typically found in late autumn/early winter) and the wet weather experienced by much of the country during autumn. 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 also recorded in the midlands, with a smaller number of positive test results seen across Leinster. The maps suggest a gradual expansion of the area where liver fluke is active, and an increased prevalence of liver fluke in affected areas.  Please see Figures 1 and 2 above.

As can be seen from Figure 1 above, some parts of the country were represented on the November survey by a relatively small number of flocks. Accordingly, farmers should exercise caution when interpreting the results of the November 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.

 

Species: Multi-Species
11:46 AM on Fri, 10 January