Determining the Prevalence and Seasonality of Fasciola hepatica in Pasture-based Dairy herds in Ireland using a Bulk Tank Milk ELISA

This study was financed by both the Irish dairy levy and Merial.peer-reviewedBackground Fasciola hepatica is a helminth parasite of global importance in livestock, with major economic impact. However information on F. hepatica infections in Irish pasture-based dairy herds is limited. Therefore this study was conducted in order to determine the prevalence, seasonality and management factors associated with F. hepatica. A total of 319 Irish dairy herds were selected for this study. Bulk tank milk (BTM) samples were collected from 290 dairy farms on a quarter year basis, while from a further 29 dairy farms BTM samples were collected on a monthly basis to provide a more detailed pattern of F. hepatica exposure in Irish herds. BTM samples were analysed using a commercially available F. hepatica antibody detection ELISA. Furthermore, within-herd prevalence of F. hepatica was assessed in a subset of these 29 herds (n = 17); both individual serum samples and bulk tank milk samples were collected. Results A within-herd prevalence of ≤ 50 % was found for herds with negative bulk tank milk samples. The mean prevalence of the 290 study herds was 75.4 % (Range 52 %–75.1 %), with the highest prevalence being observed in November (75.1 %). The seasonal pattern of F. hepatica shows elevated antibodies as the grazing season progressed, reaching a peak in January. A significant association was found between F. hepatica and age at first calving. Conclusion This study demonstrates that F. hepatica is present in a large proportion of Irish dairy herds and provides a basis on which control practices, particularly in adult dairy cows, can be reviewed.MerialIrish Dairy Lev

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Six-year longitudinal study of Fasciola hepatica bulk milk antibody ELISA in the dairy dense region of the Republic Ireland

peer-reviewedCompletion of the F. hepatica lifecycle is dependent on suitable climatic conditions for development of immature stages of the parasite, and its snail intermediate host. Few investigations have been conducted regarding temporal variations in F. hepatica status in Irish dairy herds. The current study aimed to conduct a longitudinal study examining annual and seasonal trends in bulk milk seropositivity over six years, while also investigating associations with soil temperature, rainfall and flukicide treatment. Monthly bulk milk samples (BTM) were submitted by 28 herds between March 2009 and December 2014. In all, 1337 samples were analysed using a Cathepsin L1 ELISA. Soil temperature, rainfall and management data were obtained for general estimating equation and regression analyses. A general decrease in milk seropositivity was observed over the six year study period and was associated with an increased likelihood of treating for liver fluke (OR range = 2.73–6.96). Annual and seasonal analyses of rainfall and F. hepatica BTM status yielded conflicting results. Higher annual rainfall (>1150 mm) yielded a lower likelihood of being BTM positive than annual rainfall of 120 mm), however, was associated with increased ELISA S/P% values (Coefficient = 9.63S/P%; P = 0.001). Soil temperature was not found to influence F. hepatica to the same extent as rainfall and may reflect the lack of severe temperature fluctuations in Ireland. Flukicides active against both immature and mature F. hepatica were approximately half as likely to record a positive F. hepatica herd BTM status than a flukicide active against only the mature stage of the parasite (OR ≅ 0.45; P < 0.01). This study highlights the importance of examining both annual and seasonal F. hepatica data, which can vary significantly. Additionally, it highlights the progress that can be achieved in fluke control by application of a continuous BTM monitoring program

Research of nitroxynil residues in bovine milk following a single administration in the dry period by ultra-performance liquid chromatography tandem mass spectrometry

Nitroxynil (NIT) is a halogenated phenol used to control fascioliasis in cattle and sheep. The Commission Regulation EU No 37/2010 has established maximum residue limits for NIT in bovine and ovine muscle (400 &mu;g kg&minus;1), fat (200 &mu;g kg&minus;1), liver (20 &mu;g kg&minus;1) and kidney (400 &mu;g kg&minus;1), and more recently in bovine and ovine milk (20 &mu;g kg&minus;1). Thirty-five pregnant dairy cows were treated in this study with nitroxynil (340 mg/mL solution for injection) at the recommended dose of 10 mg/kg body weight at the start of the dry period, <em>i.e.</em> 53 to 74 days before the expected calving. Calving occurred between 43 days and 79 days after treatment. The concentrations of NIT in the milk were monitored for up to 120 days after calving. NIT residues were extracted using acetonitrile; magnesium sulfate and sodium chloride were added to induce liquid-liquid partitioning and purified by dispersive solid phase extraction for clean-up. NIT was detected by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) in negative ionization mode. The highest concentrations of this drug were found in two animals at the first milking, 48 and 53 day post treatment with levels of 362 and 657 &mu;g kg&ndash;1, respectively. NIT residues were below the limit of detection of the method (0.24 &mu;g/kg&ndash;1) between 67 and 106 day post-treatment. Following calving, residues rapidly depleted in animals and were non-detectable from 10 to 38 days post-calving. In particular, in all animals milk resulted compliant (&lt;20 &mu;g/kg&minus;1) three days <em>post partum</em>