scholarly journals Anthelmintic resistance of Haemonchus contortus from sheep flocks in Brazil: concordance of in vivo and in vitro (RESISTA-Test©) methods

2021 ◽  
Vol 30 (2) ◽  
Author(s):  
Yousmel Alemán Gainza ◽  
Isabella Barbosa dos Santos ◽  
Amanda Figueiredo ◽  
Leonardo Aparecido Lima dos Santos ◽  
Sérgio Novita Esteves ◽  
...  
Keyword(s):  
Larval Development ◽  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Perfect Agreement ◽  
Fecal Egg Count ◽  
And Control ◽  
Total Agreement ◽  
Larval Development Test

Abstract This study evaluated the resistance status of Haemonchus contortus from sheep flocks in the state of São Paulo, Brazil, through comparison between the fecal egg count reduction test (FECRT) and the larval development test (LDT). For the FECRT, 35 sheep were selected in each of five flocks and divided into groups treated with: benzimidazole, levamisole, ivermectin, monepantel and control. Feces were collected for EPG and fecal cultures. The LDT was performed using thiabendazole (TBZ), levamisole (LEV), ivermectin aglycone (IVM-A) and Zolvix (ZLV). Resistance to all drugs was detected using FECRT in 100% of the flocks, except in relation to ZLV (40% resistant and 20% suspected of resistance). LDT indicated resistance to TBZ and IVM-A in all flocks, to LEV in 80% of flocks and to ZLV in 10%. Total agreement was obtained between the two tests for TBZ and IVM (k = 1.0), while for LEV (k = 0.8) and ZLV (k = 0.9), substantial and almost perfect agreement were obtained, respectively. The concordance between the tests was significant, thus showing that it is possible to use the outcome of the LDT to predict the FECRT, and hence validating the former as a fast diagnostic test for use by sheep farmers in Brazil.

scholarly journals The effects of flubendazole and its metabolites on the larval development of Haemonchus contortus (Nematoda: Trichostrongylidae): an in vitro study

2010 ◽  
Vol 47 (4) ◽  
pp. 269-272 ◽  
Author(s):  
H. Bártíková ◽  
L. Skálová ◽  
J. Lamka ◽  
B. Szotáková ◽  
M. Várady
Keyword(s):  
Larval Development ◽  
Haemonchus Contortus ◽  
Anthelmintic Activity ◽  
In Vitro Study ◽  
Lethal Concentration ◽  
Resistant Isolate ◽  
Susceptible Isolate ◽  
Marked Resistance ◽  
Larval Development Test

AbstractThe anthelmintic effects of flubendazole (FLU), its two main metabolites reduced flubendazole (FLU-R) and hydrolyzed flubendazole (FLU-H), and thiabendazole (TBZ) were compared using an in vitro larval development test in two isolates of Haemonchus contortus, a fully susceptible isolate (HCS) and a multi-resistant isolate (HCR). Results were quantified as 50 % lethal concentration (LC50), 99 % lethal concentration (LC99), efficacy factor (EF), and resistance factor (RF). For HCS, both LC50 and LC99 of FLU were lower than those of the reference TBZ. The anthelmintic activity of FLU-R in HCS and HCR was 13 and 6 times lower than the activity of FLU, respectively. The anthelmintic activity of FLU-H was negligible (approximately 363–853 times lower) compared to that of FLU. Although a marked resistance of the HCR isolate to TBZ was confirmed, only a low tolerance to FLU-R and slightly higher tolerance to FLU were found.

scholarly journals Comparison of two in vitro methods for the detection of ivermectin resistance in Haemonchus contortus in sheep

2016 ◽  
Vol 53 (2) ◽  
pp. 120-125 ◽  
Author(s):  
M. Urda Dolinská ◽  
A. Königová ◽  
M. Babják ◽  
M. Várady
Keyword(s):  
Drug Resistance ◽  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Economic Losses ◽  
Parasitic Nematodes ◽  
Migration Inhibition ◽  
In Vitro Methods ◽  
Parasitic Helminths

SummaryGastrointestinal parasitic nematodes in sheep cause severe economic losses. Anthelmintics are the most commonly used drugs for prophylaxis and therapy against parasitic helminths. The problem of drug resistance has developed for all commercially available anthelmintics in several genera and classes of helminths. In vitro and in vivo tests are used to detect anthelmintic resistance. Two in vitro methods (larval migration inhibition test and micromotility test) for the detection of ivermectin (IVM) resistance were compared using IVM-resistant and IVM-susceptible isolates of Haemonchus contortus. The degree of resistance for each test was expressed as a resistance factor (RF). The micromotility test was more sensitive for quantitatively measuring the degree of resistance between susceptible and resistant isolates. The RFs for this test for IVM and eprinomectin ranged from 1.00 to 108.05 and from 3.87 to 32.32, respectively.

scholarly journals Multiple anthelmintic resistance at a goat farm in Slovakia

2021 ◽  
Vol 58 (2) ◽  
pp. 173-178
Author(s):  
M. Babják ◽  
A. Königová ◽  
M. Várady
Keyword(s):  
Inhibitory Concentration ◽  
Anthelmintic Resistance ◽  
Small Ruminants ◽  
Threshold Concentration ◽  
Faecal Egg Count ◽  
Goat Farm ◽  
Threshold Criteria ◽  
Larval Development Test

Summary Cases of parasite resistance to the main classes of anthelmintics are increasingly reported from small ruminants at farms in Europe. We visited a goat farm in Slovakia in November 2019 with suspected parasite problems that reduced productivity and performed an in vivo faecal egg count reduction test (FECRT) and an in vitro larval development test (LDT) for all three main classes of anthelmintics. The lowest efficacy (60 %) detected by FECRT was for ivermectin (IVM). Benzimidazole (BZ) efficacy ranged between 80.3 and 86.5 %, and levamisole (LEV) efficacy was 94 %. The results from the in vivo FECRT test were confirmed by the in vitro LDT. Minimum inhibitory concentration (MIC) 173.6 ng/ml for IVM several times exceeded the recommended threshold of 21.6 ng/ml. Mean LD50 for BZ was equal to the threshold concentration, but the other threshold criteria indicated a low level of resistance in the population. The LDT did not indicate the presence of resistance only for LEV. The MIC 1.0 μg/ml for LEV was evaluated as susceptible with respect to species composition. Teladorsagia was the dominant genus after treatment with BZ, IVM, and LEV. Haemonchus contortus was identifi ed after treatment with BZ and LEV.

Comparison of two versions of larval development test to detect anthelmintic resistance in Haemonchus contortus

2009 ◽  
Vol 160 (3-4) ◽  
pp. 267-271 ◽  
Author(s):  
Marián Várady ◽  
Július Čorba ◽  
Valéria Letková ◽  
Gabriel Kováč
Keyword(s):  
Larval Development ◽  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Larval Development Test

Measuring the effect of avermectins and milbemycins on somatic muscle contraction of adult Haemonchus contortus and on motility of Ostertagia circumcincta in vitro

Parasitology ◽  
2014 ◽  
Vol 141 (7) ◽  
pp. 948-956 ◽  
Author(s):  
JANINA DEMELER ◽  
GEORG VON SAMSON-HIMMELSTJERNA ◽  
NICHOLAS C. SANGSTER
Keyword(s):  
Muscle Contraction ◽  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Parasitic Nematodes ◽  
Response Curves ◽  
Drug Potency ◽  
The Right ◽  
Sites Of Action

SUMMARYThe mechanism of anthelmintic resistance against the widely used macrocyclic lactones (MLs) is still not fully understood. Pharyngeal, somatic body muscles and the ovijector have been proposed as putative sites of action as well as resistance. In the present study the effects of three avermectins and three milbemycins on adult parasitic nematodes were evaluated in vitro. The Muscle Transducer system was used to investigate the effects of MLs on muscle contraction in female Haemonchus contortus and effects on motility were measured in Ostertagia (Teladorsagia) circumcincta using the Micromotility Meter. Concentration-response curves for all substances in both systems shifted to the right in the resistant isolates. Resistance was present to ivermectin (IVM) and its components IVM B1a and IVM B1b, suggesting that both components are involved in the mode of action and resistance. No consistent patterns of potency and resistance of the substances were observed except that milbemycins generally showed lower resistance ratios (RRs) than IVM. IVM and IVM B1b were the most potent inhibitors of contraction and motility in both susceptible isolates and also showed the highest RR in both species. Low RRs for milbemycins recorded in vitro for highly resistant isolates in vivo suggest that other factors such as pharmacokinetics influence drug potency in vivo.

scholarly journals Resistencia a los antihelmínticos: origen, desarrollo y control.

2003 ◽  
Vol 4 (1) ◽  
pp. 55 ◽  
Author(s):  
Dildo Márquez Lara
Keyword(s):  
Anthelmintic Resistance ◽  
Control Strategies ◽  
Small Ruminants ◽  
Nematode Resistance ◽  
Development Of Resistance ◽  
Helminth Infections ◽  
Wide Range ◽  
And Control

<p>Una variada gama de antihelmínticos modernos, con espectro amplio y alto grado de eficacia, como los benzimidazoles, los agonistas nicotínicos y las lactonas macrocíclicas, se encuentran disponibles comercialmente en el mundo para el control de las infecciones causadas por helmintos en rumiantes. El uso intensivo y la administración inadecuada de antihelmínticos, en épocas y grupos de rumiantes no apropiados, han contribuido al desarrollo de resistencia a estas sustancias, lo que constituye un obstáculo importante para el control de los endoparásitos. La resistencia antihelmíntica se ha reportado principalmente en pequeños rumiantes y es escasa la información relacionada con los nemátodos de bovinos. Se han identificado algunos factores aceleradores del proceso de desarrollo de resistencia, entre ellos factores genéticos, reproductivos y ecológicos de los parásitos, así como factores de orden antrópico, siendo la resistencia una característica heredable. El aumento de la resistencia a los antihelmínticos en la última década, así como los requerimientos de información sobre su ocurrencia e incidencia, han señalado la necesidad de desarrollar y estandarizar técnicas más sensibles para su detección. Hay varias técnicas disponibles <em>in vivo </em>e <em>in vitro </em>útiles para detectar la resistencia antihelmíntica, si bien la prueba de Reducción del Conteo de Huevos Fecales (RCH) es la más usada. La detección temprana de esta condición es un factor esencial para el control estratégico de los endoparásitos a fin de preservar la eficacia de los antihelmínticos. La presente revisión propone diferentes alternativas, químicas y no químicas, para el control de helmintos con el objeto de retardar la aparición de resistencia.</p><p> </p><p><strong>Anthelmintic resistance: origin, development and control</strong></p><p>A wide range of modern anthelmintics, with broad-spectrum and high efficacy to control helminth infections in ruminants, are commercially available, such as benzimidazoles, nicotinic agonist and macrocyclic lactones.The intensive use and inadequated dosages of anthelmintics in ruminants have contributed to develop resistance, becoming the main threat to control endoparasites. Anthelmintic resistance has been reported mainly in small ruminants, but there is scarce information about it in nematodes of cattle. Genetic, reproductive, ecological and anthropic factors have been found to enhance the development of resistance. Because nematode resistance has increased in the last decade, it is necessary to investigate about its occurrence and incidence; so, developing and standarization of improved techniques for detection of the resistance should be carried out. There are several techniques (<em>in vivo </em>and <em>in vitro</em>) available for detection of anthelmintic resistance, being the Faecal Egg Count Reduction Test (FECRT) the most commonly used. Early detection of resistance is an essential factor on parasite control strategies in order to preserve the effectiveness of anthelmintics. Different chemical and non-chemical helminth control strategies have been suggested in order to slow the onset of resistance.</p>

scholarly journals Nanoparticles as Alternatives for the Control of Haemonchus contortus: A Systematic Approach to Unveil New Anti-haemonchiasis Agents

2021 ◽  
Vol 8 ◽  
Author(s):  
Rehman Ali ◽  
Nisar Ahmad ◽  
Sakina Mussarat ◽  
Abdul Majid ◽  
Sultan F. Alnomasy ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Small Ruminants ◽  
Gastrointestinal Nematode ◽  
Future Research ◽  
Cymbopogon Citratus ◽  
Toxicological Effects ◽  
Nano Emulsion

Haemonchus contortus is an infectious gastrointestinal nematode parasite of small ruminants. This study addresses the in vitro/in vivo anti-haemonchiasis potential, toxicological effects, and mechanism of action of nanoparticles. Online databases were used to search and retrieve the published literature (2000 to 2021). A total of 18 articles were selected and reviewed, out of which, 13 (72.2%) studies reported in vitro, 9 (50.0%) in vivo, and 4 (22.2%) both in vitro/in vivo efficacy of different nanoparticles. Mostly, organic nanoparticles (77.7%) were used including polymeric (85.7%) and lipid nanoparticles (14.3%). The highest efficacy, in vitro, of 100% resulted from using encapsulated bromelain against eggs, larvae, and adult worm mortality at 4, 2, and 1 mg/ml, respectively. While in vivo, encapsulated Eucalyptus staigeriana oil reduced worm burden by 83.75% and encapsulated Cymbopogon citratus nano-emulsion by 83.1%. Encapsulated bromelain, encapsulated Eucalyptus staigeriana oil, and encapsulated Cymbopogon citratus nano-emulsion were safe and non-toxic in vivo. Encapsulated bromelain damaged the cuticle, caused paralysis, and death. Nanoparticles could be a potential source for developing novel anthelmintic drugs to overcome the emerging issue of anthelmintic resistance in H. contortus. Studies on molecular effects, toxicological consequences, and different pharmacological targets of nanoparticles are required in future research.

Molecular detection of benzimidazole resistance in Haemonchus contortus using real-time PCR and pyrosequencing

Parasitology ◽  
2009 ◽  
Vol 136 (3) ◽  
pp. 349-358 ◽  
Author(s):  
G. von SAMSON-HIMMELSTJERNA ◽  
T. K. WALSH ◽  
A. A. DONNAN ◽  
S. CARRIÈRE ◽  
F. JACKSON ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Allele Frequencies ◽  
Detection Methods ◽  
Resistance Testing ◽  
Β Tubulin

SUMMARYBenzimidazoles (BZ) are widely used to treat parasitic nematode infections of humans and animals, but resistance is widespread in veterinary parasites. Several polymorphisms in β-tubulin genes have been associated with BZ-resistance. In the present study, we investigated β-tubulin isotype 1 sequences of 18 Haemonchus contortus isolates with varying levels of resistance to thiabendazole. The only polymorphism whose frequency was significantly increased in the resistant isolates was TTC to TAC at codon 200. Real-time PCR (using DNA from 100 third-stage larvae, L3s) and pyrosequencing (from DNA from 1000–10 000 L3s) were used to measure allele frequencies at codon 200 of these isolates, producing similar results; drug sensitivity decreased with increasing TAC frequency. Pyrosequencing was also used to measure allele frequencies at positions 167 and 198. We showed that such measurements are sufficient to assess the BZ-resistance status of most H. contortus isolates. The concordance between real-time PCR and pyrosequencing results carried out in different laboratories indicated that these tools are suitable for the routine diagnosis of BZ-resistance in H. contortus. The molecular methods were more sensitive than the ‘egg hatch test’, and less time-consuming than current in vivo- or in vitro-anthelmintic resistance detection methods. Thus, they provide a realistic option for routine molecular resistance testing on farms.

scholarly journals Acyl-CoA oxidase ACOX-1 interacts with a peroxin PEX-5 to play roles in larval development of Haemonchus contortus

2021 ◽  
Vol 17 (7) ◽  
pp. e1009767
Author(s):  
Hengzhi Shi ◽  
Xiaocui Huang ◽  
Xueqiu Chen ◽  
Yi Yang ◽  
Zhao Wang ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Larval Development ◽  
Haemonchus Contortus ◽  
Developmental Regulation ◽  
Tissue Expression ◽  
Parasitic Nematodes ◽  
Acid Oxidation ◽  
Oxidation Activity

Hypobiosis (facultative developmental arrest) is the most important life-cycle adaptation ensuring survival of parasitic nematodes under adverse conditions. Little is known about such survival mechanisms, although ascarosides (ascarylose with fatty acid-derived side chains) have been reported to mediate the formation of dauer larvae in the free-living nematode Caenorhabditis elegans. Here, we investigated the role of a key gene acox-1, in the larval development of Haemonchus contortus, one of the most important parasitic nematodes that employ hypobiosis as a routine survival mechanism. In this parasite, acox-1 encodes three proteins (ACOXs) that all show a fatty acid oxidation activity in vitro and in vivo, and interact with a peroxin PEX-5 in peroxisomes. In particular, a peroxisomal targeting signal type1 (PTS1) sequence is required for ACOX-1 to be recognised by PEX-5. Analyses on developmental transcription and tissue expression show that acox-1 is predominantly expressed in the intestine and hypodermis of H. contortus, particularly in the early larval stages in the environment and the arrested fourth larval stage within host animals. Knockdown of acox-1 and pex-5 in parasitic H. contortus shows that these genes play essential roles in the post-embryonic larval development and likely in the facultative arrest of this species. A comprehensive understanding of these genes and the associated β-oxidation cycle of fatty acids should provide novel insights into the developmental regulation of parasitic nematodes, and into the discovery of novel interventions for species of socioeconomic importance.

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