<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec>
<h3>Introduction</h3>
<p>Gastrointestinal nematodes pose a threat to animal health and affect farmers by negatively impacting farm management.</p>
</sec>
<sec>
<h3>Material and Methods</h3>
<p>The study was conducted on a sheep farm with suspected reductions in the efficacies of anthelmintics. Efficacy was determined using <italic>in vivo</italic> faecal egg count reduction, <italic>in vitro</italic> egg hatch (EHT) and larval development (LDT) tests. In the first phase, 60 sheep were equally split into six groups. Group 1 received the recommended dose of albendazole (ALB), group 2 received the same after fasting for 24 h, group 3 received the dose divided into two halves at 6 h intervals, group 4 received a double dose of ALB, and group 5 received the recommended dose of ivermectin (IVM). Group 6 served as a control. The second phase of the experiment had two groups: one treated with levamisole (LEV) and a control group. Faecal samples were collected from all sheep.</p>
</sec>
<sec>
<h3>Results</h3>
<p>No reduction of egg output was observed in the groups treated with single, double, or divided doses of ALB, but one of 13.7–16.9% was noted in the fasting group. Efficacy in the IVM group ranged from 31.50 to 39.97%. The mean concentrations sufficient to prevent 50% of the eggs from hatching in the <italic>in vitro</italic> EHT and the mean concentrations in which the development of larvae to the L3 stage was inhibited by 50% in the LDT exceeded established thresholds for benzimidazoles and IVM. <italic>Haemonchus contortus</italic> was the only species identified after treatment. The LDT did not indicate the presence of resistance to LEV. All animals treated with LEV were negative for eggs 10 d after treatment.</p>
</sec>
<sec>
<h3>Conclusion</h3>
<p>Resistance to ALB and IVM in <italic>Haemonchus contortus</italic> was confirmed. Alternative approaches to improve the efficacies of benzimidazole did not sufficiently increase the efficacy, but LEV was an efficient anthelmintic treatment.</p>
</sec>
</abstract>

Introduction
Gastrointestinal nematodes pose a threat to animal health and affect farmers by negatively impacting farm management.


Material and Methods
The study was conducted on a sheep farm with suspected reductions in the efficacies of anthelmintics. Efficacy was determined using in vivo faecal egg count reduction, in vitro egg hatch (EHT) and larval development (LDT) tests. In the first phase, 60 sheep were equally split into six groups. Group 1 received the recommended dose of albendazole (ALB), group 2 received the same after fasting for 24 h, group 3 received the dose divided into two halves at 6 h intervals, group 4 received a double dose of ALB, and group 5 received the recommended dose of ivermectin (IVM). Group 6 served as a control. The second phase of the experiment had two groups: one treated with levamisole (LEV) and a control group. Faecal samples were collected from all sheep.


Results
No reduction of egg output was observed in the groups treated with single, double, or divided doses of ALB, but one of 13.7–16.9% was noted in the fasting group. Efficacy in the IVM group ranged from 31.50 to 39.97%. The mean concentrations sufficient to prevent 50% of the eggs from hatching in the in vitro EHT and the mean concentrations in which the development of larvae to the L3 stage was inhibited by 50% in the LDT exceeded established thresholds for benzimidazoles and IVM. Haemonchus contortus was the only species identified after treatment. The LDT did not indicate the presence of resistance to LEV. All animals treated with LEV were negative for eggs 10 d after treatment.


Conclusion
Resistance to ALB and IVM in Haemonchus contortus was confirmed. Alternative approaches to improve the efficacies of benzimidazole did not sufficiently increase the efficacy, but LEV was an efficient anthelmintic treatment.

Multidrug resistance in <italic>Haemonchus contortus</italic> in sheep - can it be overcome?

Journal of Veterinary Research

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Multidrug resistance in  in sheep - can it be overcome?

Introduction
Gastrointestinal nematodes pose a threat to animal health and affect farmers by negatively impacting farm management.


Material and Methods
The...

Multidrug resistance in Haemonchus contortus in sheep - can it be overcome?

Publié en ligne: 19 déc. 2023

Pages: 575 - 581

Reçu: 22 mai 2023

Accepté: 09 oct. 2023

DOI: https://doi.org/10.2478/jvetres-2023-0057

Mots clés
sheep, drug resistance, alternative treatment, levamisole

© 2023 Michal Babják et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Multidrug resistance in Haemonchus contortus in sheep - can it be overcome?

Publié en ligne: 19 déc. 2023

Pages: 575 - 581

Reçu: 22 mai 2023

Accepté: 09 oct. 2023

DOI: https://doi.org/10.2478/jvetres-2023-0057

Mots cléssheep, drug resistance, alternative treatment, levamisole

© 2023 Michal Babják et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Mots clés
sheep, drug resistance, alternative treatment, levamisole