Anthelmintic resistance.
Abstract: In populations of livestock in which anthelmintics have become the only means of control, individual worms in some species of helminths evade the effects of specific anthelmintics. If these resistant individuals are selected (by removing the susceptible individuals in the population) then the resistant worm population on individual farms becomes dominant in both numbers and effect. This selection of anthelmintic resistant populations is most often reported in equids and small ruminants (the hosts in which anthelmintics are used most frequently). There is little evidence of anthelmintic resistance by Ostertagia in cattle but an understanding of the problem in other grazing species may aid in delaying its onset. Benzimidazole/phenothiazine resistance by small strongyles in horses in widespread. Resistance by various geographic strains of Haemonchus, Teladorsagia and Trichostrongylus against all of the commonly used classes of anthelmintics in small ruminants has been verified. The failure of levamisole to remove adult Ostertagia ostertagi from cattle has been reported in several geographical areas. Resistance is an individual farm problem and each premise has to be evaluated as to which anthelmintics can be used. Drug rotation, especially rapid rotation (less than 1 year) selects for multiple drug resistance. Epidemiologic treatment selects for resistance, but if properly used, requires considerably fewer treatments to prevent disease and the development of resistant populations will be slowed. A combination of strategic and tactical treatments along with evaluation of anthelmintics will be required to enable producers to raise livestock in maximum production units.
Publication Date: 1993-02-01 PubMed ID: 8484205DOI: 10.1016/0304-4017(93)90053-pGoogle Scholar: Lookup
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Summary
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The research investigates the issue of anthelmintic resistance in nematode parasites that infect various livestock animals like sheep, goats, horses, cattle, and pigs. The study also presents improved methods for the detection of this resistance and explores the physiological alterations in the parasites that cause the said resistance.
About Anthelmintic Resistance
- The research suggests that anthelmintic resistance, a condition where nematode parasites develop immunity against the drugs designed to kill them, is widespread in sheep, goats, and horses. This resistance is also developing in parasites in cattle and has even been noticed in pig parasites.
- The research brings up that Benzimidazole, Levamisole/Morantel, Ivermectin, and Closantel resistances are common in parasites of sheep and goats.
- The article suggests that this resistance might develop wherever anthelmintics (parasitic worm-killing drugs) are frequently used and it can be detected if investigated.
Detecting Anthelmintic Resistance
- The reduction in worm count or egg count after treatment is useful for detecting any type of anthelmintic resistances.
- The researchers claim to have developed more economical, faster, and more sensitive in vitro assays (tests conducted in a controlled environment outside a living organism) for detecting this resistance. Some tests, like the egg hatch assay, are specific for a particular class of anthelmintics.
- The research predicts that a better understanding of anthelmintic actions’ biochemistry and molecular genetics should lead to the creation of more sensitive assays for detecting resistance in individual nematodes (worms).
Understanding Resistance at the Molecular Level
- Levamisole/Morantel resistance is associated with changes in cholinergic receptors (which receive nerve signals) in the resistant worms.
- In contrast, Ivermectin works by binding to a glutamate receptor of a membrane chloride channel. This receptor has been expressed in vitro, allowing further studies of Ivermectin’s interaction with this receptor and how it may change in resistance cases.
- Benzimidazole resistance seems to be related to a change in beta-tubulin genes. This alteration results in reduced or abolished high-affinity binding of Benzimidazoles for tubulin, a protein in these organisms. These findings can be used to develop DNA probes for Benzimidazole resistance/susceptibility in individual organisms.
Cite This Article
APA
Craig TM.
(1993).
Anthelmintic resistance.
Vet Parasitol, 46(1-4), 121-131.
https://doi.org/10.1016/0304-4017(93)90053-p Publication
Researcher Affiliations
- Department of Veterinary Pathobiology, Texas A&M University, College Station 77843.
MeSH Terms
- Animals
- Animals, Domestic
- Anthelmintics / pharmacology
- Anthelmintics / therapeutic use
- Cattle
- Cattle Diseases / drug therapy
- Drug Resistance
- Helminths / drug effects
- Levamisole / therapeutic use
- Nematode Infections / drug therapy
- Nematode Infections / veterinary
- Ostertagiasis / drug therapy
- Ostertagiasis / veterinary
References
This article includes 78 references
Citations
This article has been cited 4 times.- Sharma N, Hunt PW, Hine BC, Ruhnke I. The impacts of Ascaridia galli on performance, health, and immune responses of laying hens: new insights into an old problem. Poult Sci 2019 Dec 1;98(12):6517-6526.
- Puspitasari S, Farajallah A, Sulistiawati E, Muladno. Effectiveness of Ivermectin and Albendazole against Haemonchus contortus in Sheep in West Java, Indonesia. Trop Life Sci Res 2016 Feb;27(1):135-44.
- Chattopadhyay AK, Bandyopadhyay S. Seasonal variations of EPG Levels in gastro-intestinal parasitic infection in a southeast asian controlled locale: a statistical analysis. Springerplus 2013;2:205.
- Blouin MS, Yowell CA, Courtney CH, Dame JB. Host movement and the genetic structure of populations of parasitic nematodes. Genetics 1995 Nov;141(3):1007-14.
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