Occurrence of anthelmintic resistant nematodes on sheep farms in England and goat farms in England and Wales

Hong, C.; Hunt, KR; Coles, G.C.

doi:10.1136/vr.139.4.83

Cited by 63 publications

(35 citation statements)

References 13 publications

(13 reference statements)

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“…T. circumcincta is one of the most prevalent specie parasitising small ruminants in Spain (Compair6 Fernfindez and Tarazona Vilas, 1985), while benzimidazoles are the most frequently used anthelmintics in this country (Coles et al, 1993). The results are in accordance with studies in Scotland in goats and sheep which have shown Teladorsagia species to have the greatest propensity for developing resistance to the benzimidazoles (Jackson et al, 1992a), while in England, T. circumcincta seems to be the main species in sheep and Haemonchus contortus in goats (Hong et al, 1996). The presence in the post-treatment larval cultures of Oesophagostomum and Trichostrongylus suggests either the possibility of resistance in these species or a lower efficacy of netobimin against these species.…”

Section: Discussionsupporting

confidence: 80%

“…First, goats could have acted as carriers of anthelmintic resistant strains of nematodes since they were originally imported from the UK, where a high prevalence of anthelmintic resistance in fibre producing goats has been recorded (Jackson et al, 1992b;Hong et al, 1996). The other possibility is the acquisition of resistance once the animals arrived in Spain.…”

Section: Discussionmentioning

confidence: 99%

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Anthelmintic resistance in nematode parasites from goats in Spain

Requejo-Fernández

Martínez²,

Meana

et al. 1997

Veterinary Parasitology

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In a flock of cashmere goats sited in Asturias (NW, Spain) diminished efficacy was observed following treatment with netobimin and consequently a study to demonstrate the existence of anthelmintic resistance and the species of nematode involved was conducted. Results from faecal egg count reduction tests before and after treatment with netobimin or ivermectin showed efficacies of 89.4 (81.8-94.8) and 99.7% (93.9-99.9%), respectively. Teladorsagia circumcincta was found to be the dominant species involved in netobimin resistance. Effective dose (EDs0) values in the egg hatch assay of 0.22 ~g thiabendazole ml -~ confirmed the existence of benzimidazole carbamate resistant nematodes. To the best of our knowledge, this is the first report on the existence of anthelmintic resistant nematodes from ruminants in Spain. © 1997 Elsevier Science B.V.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Anthelmintic resistance in nematode parasites from goats in Spain

Requejo-Fernández

Martínez²,

Meana

et al. 1997

Veterinary Parasitology

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“…The percentage of sheep farms with resistance to the benzimidazoles in Scotland (Mitchell et al 1991) and the east of England (Hong et al 1996) is around 14%. But in more recent studies the percentage of flocks resistant to benzimidazoles in Scotland is around 64% (Bartley et al 2003).…”

Section: Discussionmentioning

confidence: 99%

Anthelmintic resistance in trichostrongylid nematodes of sheep farms in Northwest Spain

et al. 2006

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A survey to determine the prevalence of anthelmintic resistance in nematode parasites of sheep against the three main families of anthelmintics (benzimidazoles, macrocyclic lactones and imidazothiazoles) was carried out from January 1999 to December 2003 involving 85 flocks in Northwest (NW) Spain. In the study on prevalence of resistance to benzimidazoles, faecal egg count reduction test (FECRT) showed there was resistance in 8 (12.7%) flocks, 1 (1.6%) was suspected, and 54 (85.7%) were susceptible. The results indicated that 9 flocks (34.61%) showed resistance, 1 (3.85%) showed suspected resistance, and 16 (61.54%) were susceptible to the imidazothiazoles. Against macrocyclic lactones, resistance was observed in 8 flocks (15.69%), 4 (7.84%) showed suspected resistance and 39 (76.47%) were susceptible. None of the flocks used in the study showed resistance to the three families of anthelmintics. Nevertheless, six were recorded as resistant or suspected of being resistant to two of these families of anthelmintics. Egg hatch assay (EHA) and FECRT were carried out jointly on 61 flocks, although EHA was done on a total of 83 farms. The results showed that 15 (18.07%) of the 83 flocks were resistant, with egg death 50 over 0.1 microg/ml thiabendazole, and 68 (81.93%) were susceptible to benzimidazoles. When the results between FECRT and EHA were compared, both techniques showed good correlation in field studies. Faecal cultures performed pre- and post-treatment indicated that Teladorsagia and Trichostrongylus were the main genera.

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“…The main factor evoked to select for resistance concerns treatment frequency and, "a large number of anthelmintic treatments with the same anthelmintic family for years" is taken as the key factor for selecting for resistance [91]. This statement is supported by surveys realised on a regional scale, in New Zealand [59,83]; in Malaysia [33]; in South Africa [95]; in the United Kingdom [53,75]; in Australia [36,72]. The "same" repeated anthelmintic treatment is a major cause, in experimental and oversimplified conditions (three-month-old lambs, synchronous infestation with only one to three gastro-intestinal nematode species...) of positive correlation between intensity of resistance and treatment frequency [5,66,71].…”

Section: Introductionmentioning

confidence: 99%

Sheep and goat nematode resistance to anthelmintics: pro and cons among breeding management factors

et al. 2002

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-Although the molecular bases of resistance to anthelmintic families have been intensively studied, the contributing factors for the development of anthelmintic resistance are less well known. Clear recommendations must be given to farmers in order to delay the onset of anthelmintic resistance. Until now, the main advice has concerned the reduction of treatment frequency in order to slow down the spread of resistance. Anthelmintic resistance development depends mostly on an efficient selection pressure. This means that a high treatment frequency is neither necessary nor sufficient to select for resistance. The contribution of resistant worms, which have survived an anthelmintic treatment, to the subsequent generation is the key factor that controls resistance spread. This point is illustrated by five surveys conducted on sheep and goat farms from France and Morocco. In the 52 farms studied, less than three anthelmintic treatments were given each year. Three characteristics of breeding management can be identified in the build up of anthelmintic resistance: (1) the introduction of resistant worms through the purchase of sheep/goats or the use of common pastures, grazed by several herds/flocks, (2) under-dosing of hosts and the repeated use of one class of drugs, (3) the size of the population in refugia (infective larvae on pastures) at the time of the treatment. The role played by these breeding management factors in selecting for resistance is discussed. The most efficient way to limit the increase of anthelmintic resistance remains the reduction of the selection pressure by drugs, and optimal timing to maximise their efficacy. Bien que les bases moléculaires de la résistance aux différentes familles d'anthelminthiques aient été très étudiées, les facteurs permettant le développement de la résistance anthelminthique sont moins bien connus. Des recommandations claires sont nécessaires aux éleveurs si l'on souhaite retarder l'apparition de la résistance aux anthelminthiques. La principale recommandation a consisté à réduire la fréquence des traitements de façon à ralentir le développement de la résis-tance. Le développement de la résistance anthelminthique dépend essentiellement d'une pression de sélection efficace. Cela signifie qu'une forte fréquence de traitements n'est ni nécessaire ni suffisante pour sélectionner la résistance. La contribution des vers résistants, qui ont survécu au traitement anthelminthique, à la génération suivante est le facteur clé qui contrôle le développement de la résis-tance. Ce point est illustré par cinq enquêtes réalisées dans des élevages ovins et caprins de France et du Maroc. Dans les 52 élevages étudiés, moins de trois traitements anthelminthiques par an étaient réalisés. Trois conditions d'élevage ont pu être mises en évidence comme étant impliquées dans le dé-veloppement de la résistance anthelminthique :

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Occurrence of anthelmintic resistant nematodes on sheep farms in England and goat farms in England and Wales

Cited by 63 publications

References 13 publications

Anthelmintic resistance in nematode parasites from goats in Spain

Anthelmintic resistance in nematode parasites from goats in Spain

Anthelmintic resistance in trichostrongylid nematodes of sheep farms in Northwest Spain

Sheep and goat nematode resistance to anthelmintics: pro and cons among breeding management factors

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