Prevalence of liver fluke on West Coast farms of the South Island of New Zealand sampled in the autumn and spring of consecutive lactations
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2021-07-19
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Abstract
The aim of this study was to determine the occurrence of Fasciola hepatica infection in dairy cows in this West Coast of the South Island using an ELISA of bulk milk samples (n=430) collected on one of two occasions during March (autumn) 2017 and again in October (spring). All samples were analysed using the IDEXX Fasciolosis Verification kit which estimates the infection level in the herd in 4 categories; >50% infestation (strong); 20-50% infestation (medium); <20% infestation (low); no infection. A subset (n=99) were tested twice with a one week interval to determine repeatability. A short survey was also posted to each supplier with 157 completed.
Of the 430 farms tested 133 (31%) were negative, 49 (11%) had a low infestation, 62 (14%) had a medium infestation and 186 (43%) had a strong infestation. GIS mapping of the farm locations indicated geographic grouping of farms with more severe fluke infestations. The 99 samples tested twice substantially agreed (Kappa = 0.7). Farms tested in both autumn and spring (n= 369) moderately agreed (Kappa 0.43) with an overall decrease in the spring.
From the survey 85% of farmers were aware of liver fluke on their farm during the last 5 years and 70% treated their cows with a flukicide during the dry period (winter) including 92% of the farms that tested negative.
This study indicates fasciolosis is common in this region with a disturbing number with a high prevalence in their herds. It also showed a decrease from autumn to following spring levels.
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Dowling A, Pomroy W, Howe L, Scott I, Lawrence K. 2021-07-19 to 2021-07-22. Prevalence of liver fluke on West Coast farms of the South Island of New Zealand sampled in the autumn and spring of consecutive lactations. 28th International Conference of the World Association for the Advancement of Veterinary Parasitology. Dublin.