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Poster De Conférence Année : 2019

Rapid selection of multiple-resistance to eprinomectin and benzimidazole in a dairy goat farm

Résumé

Eprinomectin belonging to the avermectin class of anthelmintics as a specially interesting low elimination in milk. It has beenwas first commercially launched in the late 90’s forin lactating cows as a pour-on formulation with a zero milk withdrawal period, and it it has beenwas recently extended registered for use for in small ruminants. Given the high prevalence of resistance to benzimidazoles (BZD) in gastrointestinal nematodes that severely compromises the nematode control in dairy goats and ewes in France, more and more dairy goats’ producersfarmers have recourseuse exclusively to eprinomectin exclusively to treat their animals. and so far, no case of resistance to this drug has been reported. More and more dairy goats’ producers have recourse exclusively to eprinomectin to treat their animals against gastrointestinal nematodes as this molecule has no withdrawal time for milk and because reports of eprinomectin resistance of these parasites are scarce compared to resistance to benzimidazoles. We report here the first case of multiple-resistance to eprinomectin and benzimidazole in a French dairy goat farm. A veterinary practitioner noted a poor response to two types of eprinomectin treatments (a topical application and an injectable formulation) with high mortality rates in a dairy goat farm where high mortality rates were reported. We therefore evaluated the efficacy of several anthelmintic drugs (eprinomectin, topical and subcutaneous routes, moxidectin and fenbendazole), Therefore, a using the ffecal egg count reduction test was performed according to the WAAVP guidelines to. In parallel, nematode evaluate the efficacy of eprinomectin (topical and subcutaneous routes), moxidectin and fenbendazole. In addition, plasmatic concentrations of eprinomectin were measured in both eprinomectin-treated groups at day 2 and day 5 post-treatment. Bulk larval cultures were made in all groups at day 0 and day 14 post-treatment and species were identified at day 0 and 14 post-treatment after bulk larval cultures, by by morphology and real-time PCR. Plasma concentrations of eprinomectin were analysed by HPLC at day 2 and 5 post-treatment in eprinomectin-treated groups. The percentages of reduction of eggEgg excretionss were lowremained high in animals in thetreated with topicallly eprinomectin treated group (-16.7% (CI: -237 to 59)) and in the subcutaneously eprinomectin treated group (21.5% (CI: -126 to 73)) eprinomectin, and with fenbendazole (-5.8% (CI: -205 to 63)). Haemonchus contortus was the main species identified by morphology and real-time PCR before and after treatment (97 to 98% of identified larvae), followed by Trichostrongylus colubriformis. Plasmatic concentrations of eprinomectin showed valueswere above two 2 ng/ml in all eprinomectin-treated animals at day 2 post-treatment, indicating that suggesting that the lack of effect of this drug was not due to a weak low exposure of the worms to eprinomectin. Moreover, the percentage of reduction was very low (-5.8% (CI: -205 to 63)) in the fenbendazole-treated group whereas Interestingly, moxidectin treatment was remains totally effective. Haemonchus contortus was the main species identified by morphology and real-time PCR before and after treatment (97 to 98% of identified larvae) followed by Trichostrongylus colubriformis. This is the first report of multiple-resistance to eprinomectin and benzimidazole of a Haemonchus contortus population in a French dairy goat farm, w.ith moxidectin being a relevant alternative in this case.
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Dates et versions

hal-04632464 , version 1 (02-07-2024)

Identifiants

  • HAL Id : hal-04632464 , version 1

Citer

Léa Bordes, Nicolas Dumont, Anne Lespine, Elise Souil, Jean-Francois Sutra, et al.. Rapid selection of multiple-resistance to eprinomectin and benzimidazole in a dairy goat farm. 27th Conference of the World Association for the Advancement of Veterinary Parasitology, Jul 2019, Madison, WI, USA, United States. ⟨hal-04632464⟩
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