Recovery of fenbendazole efficacy on resistant Haemonchus contortus by management of parasite refugia and population replacement

Muchiut, Sebastián; Fernández, A.; Lloberas, Mercedes; Steffan, Pedro; Luque, S.; Cardozo, Patricia; Bernat, G.; Riva, Eliana; Fiel, César

doi:10.1016/j.vetpar.2019.06.003

Cited by 17 publications

(7 citation statements)

References 17 publications

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“…The reduction of Trichostrongylus/Teladorsagia spp. and O. columbianum and increase of H. contortus post-treatment could be attributed to high levels of pasture infectivity as a result of shorter generation interval of H. contortus which allows for greater contamination of pastures and re-infection of animals [34].…”

Section: Discussionmentioning

confidence: 99%

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February-2021

2021

Vet World

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Background and Aim: Previous studies recorded the prevalence of gastrointestinal nematodes (GIN) in Limpopo Province. However, the studies did not address the seasonal patterns of infection and did not cover all districts of Limpopo Province, namely; Capricorn, Sekhukhune, Waterberg, Mopani, and Vhembe. It is, therefore, important to provide up to date information on the prevalence and seasonal occurrence data of GIN in all districts of Limpopo province. The present study was conducted to determine the occurrence of anthelmintic resistance (AR) and document the prevalence of GIN infecting sheep in five districts of Limpopo Province, South Africa.Materials and Methods: Forty animals in each district were used for fecal egg count reduction test (FECRT) to determine AR against ivermectin (0.2 mg/kg), levamisole (LEV) (5 mg/kg), and albendazole (7.5 mg/kg). Egg hatch test (EHT) was used to determine AR against thiabendazole (TBZ) and micro-agar larval development test (MALDT) was used for both TBZ and LEV. Naturally, infected sheep (n=780) were sampled for prevalence across five districts of Limpopo. FAMACHA © eye-color score estimations were also performed for each study animal.Results: FECRT showed occurrence of AR in most of the districts and a few with suspected resistance. EHT results showed AR development against TBZ for all districts, while the MALDT showed no AR against LEV in all districts, but detected AR against TBZ in Sekhukhune, Capricorn, and Waterberg. Haemonchus contortus was the most resistant species. A high nematode prevalence (88-100%) and 1210-1861 eggs per gram (EPG) was observed in all districts during the hot wet season, decreasing to 75-80% (453-1202 EPG) during the cold dry season. The sheep revealed a FAMACHA © mean score of 3, indicating mild anemia during the hot wet season except for Vhembe district that revealed a FAMACHA © mean score of 4 during the hot wet season, indicating anemia. Conclusion:AR recorded in Limpopo Province may be due to under-dosing caused by lack of weighing equipment and high treatment frequencies due to lack of proper training on anthelmintic use. The detection of AR in Limpopo is an important finding because it will help in outlining effective management systems against GIN.

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Section: Discussionmentioning

confidence: 99%

“…The high biotic potential and shorter generation interval of Haemonchus spp. allow for greater contamination of pastures and re-infection of animals [34], which probably accounts for its higher prevalence than Trichostrongylus/Teladorsagia spp. and O. columbianum encountered in this study.…”

Section: Discussionmentioning

confidence: 99%

February-2021

2021

Vet World

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“…Ellos describieron la presencia de C. curticei al este de la región semiárida pampeana en una baja carga y principalmente en asociación a sistemas extensivos que basan su oferta forrajera en pastizales naturales. Por otro lado, otros trabajos la mencionan como género prevalente en ensayos de eficacia antihelmíntica en la región del noreste argentino (Fiel et al, 2011) y en la región Sub Húmeda Pampeana (Steffan et al, 2011;Muchiut et al, 2019).…”

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“…En este estudio esta longitud fue de 135,2 a 160,8 µm. Dichas diferencias podrían estar debidas a la adaptación del parásito a los distintos ambientes en donde fueron identificados, ya que, en el caso de Gibbons (1981) el estudio se efectuó sobre especímenes provenientes del continente africano y Ransom (1911) (Steffan et al, 2011;Muchiut et al, 2019), en clima templado semiárido (Suarez et al, 1994) y en climas subtropicales (Fiel et al, 2011). Nuestro hallazgo constituye el primero en su tipo en la región del NOA y demuestra la adaptación de C. curticei a un clima de tipo serrano sub-andino.…”

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Primer registro de Cooperia curticei (Strongylida: Trichostrongylidae) en un ovino de la región del noroeste argentino

Olmos¹,

Caro

Avellaneda-Cáceres

et al. 2021

FAVE Cs Vet

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Cooperia curticei, es un nematodo afín a los ovinos que se aloja en el intestino delgado de estos. Su presencia en Argentina ha sido registrada en ambientes como la región semiárida en la Pampa, subhúmeda pampeana en Buenos Aires y en la región subtropical en Corrientes. El objetivo de este trabajo es notificar la presencia de Cooperia curticei en intestino delgado de un ovino proveniente de la localidad de Cerrillos en Salta. En el intestino delgado se determinó una carga de 600 formas adultas de Cooperia spp. Estas fueron identificadas como Cooperia curticei. Como características taxonómicas de relevancia las ramas del rayo dorsal se curvaban hacia atrás mostrando una forma de lira. En cuanto a las espículas, midieron en promedio 146,8 µm (± 5,24), con una concavidad marcada en parte media del cuerpo y con un tallo con una curvatura final similar a un pie. Este hallazgo constituye el primero en su tipo en la región del NOA y demuestra la adaptación de C. curticei a un clima de tipo serrano sub-andino. Este trabajo complementa lo descripto previamente en la región, en donde se menciona la presencia de Cooperia spp en ovinos, sin especificar su especie.

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“…Singh and Gupta (2009) reported partial reversion to susceptibility of fenbendazole and levamisole resistant strain of H. contortus on an organized sheep farm after switching over to ivermectin and closantel for 12 years. Recently, Muchiut et al (2019) reported recovery of FBZ efficacy against a resistant population of H. contortus by means of refugia management and subsequent introduction of susceptible population. The possible reason for enhanced efficacy could be that any initial fitness cost associated with resistant genotypes would have been eroded by re-association of resistance and fitness traits during the selection process (Prichard 1990).…”

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confidence: 99%

Reversion towards benzimidazole susceptibility in Haemonchus contortus by resistance management strategies

Swarnkar

Singh

Khan

et al. 2021

Indian J of Anim Sci

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A study was aimed to observe the impact of withdrawal of anthelmintic type and increase in refugia through community dilution on reversion towards benzimidazole (BZ) susceptibility in Haemonchus contortus at an organized sheep farm in semi-arid Rajasthan. In sheep flocks of ICAR-Central Sheep and Wool Research Institute, Avikanagar reduced efficacy (80%) on faecal egg count reduction test (FECRT) with ED50 of 0.239 μg thiabendazole (TBZ)/ml on egg hatch assay (EHA) indicative of emergence of H. contortus resistant to BZ was observed in the year 1995. Following discontinuation of BZ for deworming at farm since 1996, the efficacy varied between 0-44% in the year 2000 with predominance of BZ-resistant alleles (>90%) between the year 2005 to 2010. efficacy was still low (26% on FECRT, ED50 of 0.196 Î¼g TBZ/ml on EHA) even after 15 yr post withdrawal (in 2010). Later on, the concept of community dilution and refugia were implemented for worm management. With these strategies, during 2018-20 (22 yr post withdrawal) a significant improvement (86-93%) in efficacy of BZ was noticed against H. contortus. Simultaneously, the ED50 values ranged from 0.011 to 0.119 with an average of 0.075±0.008 μg TBZ/ml on EHA with prevalence of BZ susceptible alleles up to 48% on allele specific PCR assay. The study indicates the possibility of reversion to BZ susceptibility in H. contortus population in farm area with community dilution and refugia based worm management strategies.

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Recovery of fenbendazole efficacy on resistant Haemonchus contortus by management of parasite refugia and population replacement

Cited by 17 publications

References 17 publications

February-2021

February-2021

Primer registro de Cooperia curticei (Strongylida: Trichostrongylidae) en un ovino de la región del noroeste argentino

Reversion towards benzimidazole susceptibility in Haemonchus contortus by resistance management strategies

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