Considerable research has been directed towards optimising in vitro tests that can diagnose resistance in pre-parasitic stages of parasites. The objective of this study was to compare the in vivo faecal egg count reduction test (FECRT), the in vitro egg hatch test (EHT), and the molecular determination of the frequency of a codon 200 allele of β-tubulin isotype 1 associated with benzimidazole resistance in larval stages of Haemonchus contortus obtained from infected goats. Animals were infected with composite infective doses representing 10, 20, 30, 40, 60, and 80% resistant alleles. Faecal samples for the EHT were collected on 28, 33, and 35 days post-infection. The results of the in vivo FECRT indicated that albendazole treatment reduced infections consisting of composite doses of 10, 20, 30, 40, 60, and 80% larvae of the resistant isolate by 91.3, 78.0, 63.3, 48.4, 36.5, and 41.4%, respectively. The drug concentration at which 50% of the eggs were prevented from developing hatching larvae (ED50) in the in vitro EHT varied from 0.09 ± 0.01 to 15.63 ± 12.10 μg/mL thiabendazole. The results of the in vitro EHT indicated that the test could estimate in vivo resistance well. The EHT could thus accurately estimate the in vivo efficacy of the drug and percentage of the resistance allele in the population using hatching parameters in delineation doses. This finding was also supported by comparing the FECRT data to the hatching percentages in the EHT on 30 goat farms in Slovakia with natural mixed infections of gastrointestinal parasites.

TITLE: Le test d’éclosion des œufs in vitro prédit-il l’échec du traitement au benzimidazole pour Haemonchus contortus ? ABSTRACT: Des efforts de recherche considérables ont été consacrés à l’optimisation des tests in vitro permettant de diagnostiquer la résistance des parasites aux stades préparasitaires. L’objectif de cette étude était de comparer le test de réduction du nombre d’œufs fécaux in vivo (TRNOF), le test d’éclosion des œufs in vitro (TEO) et la détermination moléculaire de la fréquence d’un allèle du codon 200 de l’isotype 1 de la β-tubuline associé à résistance au benzimidazole au stade larvaire d’Haemonchus contortus, obtenus à partir de chèvres infectées. Les animaux ont été infectés avec des doses infectieuses composites représentant 10, 20, 30, 40, 60 et 80 % d’allèles résistants. Des échantillons de matières fécales ont été prélevés pour le TEO aux jours 28, 33 et 35 après l’infection. Les résultats de la TRNOF in vivo ont indiqué que le traitement à l’albendazole réduisait respectivement de 91,3, 78,0, 63,3, 48,4, 36,5 et 41,4 % les infections composées de doses composites de 10, 20, 30, 40, 60 et 80 % de larves de l’isolat résistant. La concentration de médicament à laquelle 50 % des œufs ont été empêchés de développer des larves qui éclosent (DE50) dans le TEO in vitro variait de 0,09 ± 0,01 à 15,63 ± 12,10 μg/mL de thiabendazole. Les résultats du TEO in vitro ont indiqué que le test pouvait correctement estimer la résistance in vivo. Le TEO a ainsi pu estimer avec précision l’efficacité in vivo du médicament et le pourcentage de l’allèle de résistance dans la population en utilisant des paramètres d’éclosion dans les doses de délimitation. Cette constatation a également été étayée par la comparaison des données du TRNOF aux pourcentages d’éclosion dans le TEO sur 30 élevages de chèvres en Slovaquie, avec des infections mixtes naturelles de parasites gastro-intestinaux.

• Keywords
• Anthelmintic resistance, Detection methods, Egg hatch test, Goats, Haemonchus contortus,
• MeSH
• Anthelmintics * pharmacology   therapeutic use   MeSH
• Benzimidazoles pharmacology   therapeutic use   MeSH
• Feces MeSH
• Haemonchus * genetics   MeSH
• Drug Resistance MeSH
• Sheep Diseases * MeSH
• Sheep MeSH
• Parasite Egg Count veterinary   MeSH
• In Vitro Techniques MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anthelmintics * MeSH
• Benzimidazoles MeSH

BACKGROUND: Strongylid nematode infections may negatively affect both animal health and welfare, with deleterious consequences for livestock productivity. Many farmers in recent decades have relied on anthelmintics as the sole strategy of control, but the intensive use of these chemotherapeutics has led to the development of anthelmintic resistance (AR). Knowledge of both the efficacy of anthelmintics and factors promoting AR are essential to effectively control nematode infections, but no information on these topics for goats in the Czech Republic (CR) is available. This survey aimed to determine the occurrence of AR at Czech goat farms and to identify risk factors for the development of AR. A total of 24 herds of dairy goats across the CR were evaluated using in vitro tests for detecting AR, and a questionnaire survey was carried out to evaluate factors associated with AR. RESULTS: Resistance against benzimidazoles was confirmed at 18 (75%) farms, and the level of resistance was high in four (22%) of the affected herds based on the egg hatch test. Ivermectin-resistant nematodes were detected in 13 (54%) herds using the larval development test; Teladorsagia/Trichostrongylus and Haemonchus were the predominant types of resistant larvae. Eight (62%) of the affected herds were evaluated as highly resistant to ivermectin. Eleven (46%) of the herds were resistant to both benzimidazoles and ivermectin. This report is the first on dual AR in the CR. A univariate logistic regression analysis indicated that a high stocking rate and farmer inexperience were significantly associated with ivermectin and benzimidazole resistance, respectively. CONCLUSIONS: The results of our survey suggest that AR is widespread amongst herds of dairy goats in the CR, likely due to inappropriate practices of pasture and health management. AR may be an issue for expanding dairy-goat production in the CR in the near future unless both veterinary practitioners and farmers widely adopt strategies to prevent the development of AR.

• Keywords
• Caprine gastrointestinal nematodes, Control, Dual resistance, Farmer experience, In vitro test, Stocking rate,
• MeSH
• Anthelmintics pharmacology   MeSH
• Benzimidazoles MeSH
• Nematoda drug effects   growth & development   MeSH
• Ivermectin MeSH
• Goats MeSH
• Larva MeSH
• Drug Resistance * MeSH
• Dairying methods   MeSH
• Nematode Infections drug therapy   veterinary   MeSH
• Goat Diseases drug therapy   parasitology   MeSH
• Surveys and Questionnaires MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Anthelmintics MeSH
• benzimidazole MeSH Browser
• Benzimidazoles MeSH
• Ivermectin MeSH