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From field to genetics : anthelmintic resistance in the equine roundworm Parascaris univalens

Martin, Frida (2021). From field to genetics : anthelmintic resistance in the equine roundworm Parascaris univalens. Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880
ISBN 978-91-7760-790-8
eISBN 978-91-7760-791-5
[Doctoral thesis]

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The equine roundworm Parascaris univalens is a common parasite of foals. Most foals show mild clinical symptoms, but large worm burdens can lead to severe colic and even death. Regular treatment with anthelmintic drugs has resulted in resistance development, mainly to ivermectin but also to pyrantel and fenbendazole in sporadic cases. In Sweden, resistance to ivermectin is considered to be widespread.
The aim of the thesis was to examine the efficacy of anthelmintic drugs on stud farms in Sweden and Iceland, develop novel models for research and study genetic mechanisms potentially involved in drug metabolism and anthelmintic resistance.
Faecal egg count reduction tests showed that resistance to both pyrantel and fenbendazole has emerged on Swedish stud farms, and that ivermectin resistance is common on Icelandic farms. Due to the potentially lethal consequences of infection, this is a serious situation. We developed a novel method to hatch P. univalens eggs in order to use larvae in in vitro experiments to study resistance mechanisms. Quantitative PCR, RNA sequencing and amplicon sequencing were used to study genetic and transcriptomic mechanisms behind anthelmintic resistance in P. univalens. Several genes coding for drug metabolising enzymes, transport proteins and a possible drug target for ivermectin were found to be differentially expressed in P. univalens after exposure to anthelmintic drugs. However, mutations in β-tubulin genes responsible for benzimidazole resistance in many other parasitic nematodes were not present in a fenbendazole-resistant P. univalens population.
In conclusion, the current level of resistance in P. univalens has been updated in this thesis, a novel research method has been developed and novel candidate genes for future research have been identified.

Authors/Creators:Martin, Frida
Title:From field to genetics : anthelmintic resistance in the equine roundworm Parascaris univalens
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2021
Number of Pages:82
Publisher:Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-790-8
ISBN for electronic version:978-91-7760-791-5
Publication Type:Doctoral thesis
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Clinical Science
Keywords:macrocyclic lactone, ivermectin, benzimidazole, fenbendazole, thiabendazole, pyrantel, efficacy, foal, hatching, amplicon sequencing
Permanent URL:
ID Code:25532
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Department of Biomedical Science and Veterinary Public Health
Deposited By: SLUpub Connector
Deposited On:29 Sep 2021 11:25
Metadata Last Modified:29 Sep 2021 11:31

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