Evaluatie van twee intensieve behandelingsschema’s tegen Psoroptes ovis-schurft bij Belgisch witblauwe runderen op negen Vlaamse rundveebedrijven

Sarré, Cédric; Geurden, Thomas; Vercruysse, Jerôme; Wilde, Neil; Casaert, Stijn; Claerebout, Edwin

doi:10.21825/vdt.v84i6.16427

Cited by 5 publications

(16 citation statements)

References 6 publications

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“…Despite numerous field observations and a few published reports of treatment failure against P. ovis in cattle, the presence of resistant mites was not confirmed [3,13,18]. The objectives of this study were (i) to investigate the presence of ML resistance in beef cattle in Belgium and The Netherlands using different in vivo parameters; and (ii) to evaluate an in vitro test based on the method of Brimer et al [19] as a potential diagnostic tool for ML resistance in P. ovis.…”

Section: Introductionmentioning

confidence: 94%

“…Treatment failure with ML products in cattle has been reported by Lekimme et al [13], Mitchell et al [14] and Sarre et al [3]. Potential reasons for treatment failure are noncompliance with the recommended 'good practice' treatment and acaricide resistance.…”

Section: Introductionmentioning

confidence: 97%

“…Excessive scratching causes lesions which have a higher chance of secondary bacterial infection. In extreme cases, the lesions can generalize and result in the death of the animal [1][2][3][4]. Diminished animal welfare and financial losses are seen on farms with P. ovis problems [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…The hair needs to be sheared and crusts need to be removed prior to treatment. Treatment should be applied to all in-contact animals and not only the clinically infested animals [3,7,11,12].…”

Section: Introductionmentioning

confidence: 99%

“…Potential reasons for treatment failure are noncompliance with the recommended 'good practice' treatment and acaricide resistance. Suboptimal treatment cannot be ruled out in the studies mentioned above, as either a long treatment interval (14 days) was used [13] or not all animals were treated in every treatment round [3]. Sarre et al [15] mentioned that less than half of the Belgian farmers applied correct treatment against Psoroptes.…”

Section: Introductionmentioning

confidence: 99%

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Resistance against macrocyclic lactones in Psoroptes ovis in cattle

et al. 2020

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Background: Psoroptic mange is an important disease in Belgian Blue cattle. Treatment failure of macrocyclic lactones against Psoroptes ovis has been reported, but clear evidence of in vivo resistance is lacking. This study assessed the efficacy of macrocyclic lactone products on 16 beef farms in Belgium and the Netherlands in vivo and in vitro. Methods:On each farm a group of animals (n = 7-14) with psoroptic mange was treated with two subcutaneous injections of a macrocyclic lactone product with 7-10 days interval (15 farms) or a single injection with a long-acting macrocyclic lactone (1 farm). In vivo efficacy was assessed by the reduction in mite counts, clinical index (proportion of the body surface affected by lesions), the proportion of the animals with negative mite counts after the first treatment round and the number of treatment rounds needed to obtain zero mites counts in all animals. A mite population was categorized as sensitive when the mite count reduction after the first treatment round > 95% and the lower limit of the uncertainty interval > 90%. Resistance was detected when both parameters were below their threshold and suspected when one parameter was too low. In vitro knockdown and mortality were evaluated in a contact test. Results:The proportion of the animals with negative mite counts after the first treatment round varied from 0 to 80%. All farms needed two or more treatments rounds to obtain zero mite counts on all animals. Clinical index only started to reduce after the second treatment round. Mite populations from three farms were categorized as sensitive, one as suspected resistant and 12 as resistant. No correlation was found between in vitro lethal dose 50 and knockdown dose 50 values and in vivo efficacy parameters. Conclusions:Unambiguous treatment failure was detected on 12 out of 16 farms, confirming the presence of macrocyclic lactone resistance on Belgian Blue beef farms. In vitro parameters could not discriminate the farms based on their in vivo sensitivity. The mean reduction in mite counts and the lower limit of the confidence interval are proposed as parameters to identify acaricide resistance.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resistance against macrocyclic lactones in Psoroptes ovis in cattle

et al. 2020

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New insights into the use of a mite count reduction test for the detection of therapeutic acaricide efficacy in Psoroptes ovis in cattle

Mol

Claerebout

Casaert

et al. 2020

International Journal for Parasitology: Drugs and Drug Resistan

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When used for the evaluation of drug efficacy against Psoroptes ovis , the diagnostic performance of different sampling strategies for a mite count reduction test (MCRT) remains unclear. In the present study, a novel simulation framework was constructed that accounted for relevant biological features of P. ovis infestations in cattle and that was parameterized with field data from 16 farms (154 animals). Second, this framework was applied to explore the impact of study specific factors (number of animals, number of sampled lesions, and number of scrapings per lesion) and biological factors (mite infestation intensity and size of lesions) on the diagnostic performance of MCRT. Its outcome provided a basis to determine the diagnostic performance of MCRT when it was applied according to the World Association for the Advancement in Veterinary Parasitology (WAAVP) and the European Medicine Agency (EMA) guidelines, and to formulate recommendations to ensure a good diagnostic performance of the MCRT. For both guidelines, the MCRT allowed to correctly detect (power 80%) reduced and normal efficacy when the therapeutic efficacy was <70%, and ≥95%, respectively. The results highlighted a reliable diagnostic performance of the MCRT when performed as recommended by WAAVP and EMA for the detection of normal drug efficacy. When used for the detection of reduced efficacy, therapeutic efficacies between 70% and 90% could not be detected with sufficient reliability. The diagnostic performance can be improved by increasing the total number of skin scrapings (increasing the number of animals, number of sampled lesions and/or number of samples per lesion). In order to help researchers and veterinarians to optimize the design of the MCRT to their field settings, the findings were translated into a simple tool.

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Acaricidal activity of plant-derived essential oil components against Psoroptes ovis in vitro and in vivo

et al. 2019

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Background Treatment of Psoroptes ovis in cattle is limited to topical acaricides or systemic treatment with macrocyclic lactones. Treatment failure of macrocyclic lactones has been reported. The aim of this study was to evaluate a potential alternative treatment against P. ovis . Methods The acaricidal activity against P. ovis of four plant-derived essential oil components, i.e. geraniol, eugenol, 1,8-cineol and carvacrol, was assessed in vitro and in vivo . In vitro contact, fumigation and residual bioassays were performed. In addition, 12 Belgium Blue cattle were artificially infested and treated topically once a week for three successive weeks with carvacrol in Tween-80 (treatment group) or with Tween-80 alone (control). The efficacy of carvacrol was determined by the reduction in lesion size and mite counts. Six additional animals were topically treated with carvacrol to assess local adverse reactions. Results Three components showed a concentration-dependent acaricidal activity in a contact assay, with LC 50 of 0.56, 0.38 and 0.26% at 24 h for geraniol, eugenol, and carvacrol, respectively. However, 1,8-cineol showed no activity at any of the tested concentrations in a contact bioassay. In a fumigation bioassay, carvacrol killed all mites within 50 min after treatment, whereas geraniol, eugenol and 1,8-cineol needed 90 to 150 min. Following a 72 h incubation period in a residual bioassay, carvacrol killed all mites after 4 h of exposure to LC 90, while geraniol and eugenol killed all mites only after 8 h exposure. Based on these results, carvacrol was further assessed in vivo . Mite counts in the treatment group were reduced by 98.5 ± 2.4% at 6 weeks post-treatment, while in the control group the mite population had increased. Topical application of carvacrol only caused mild and transient erythema 20 min after treatment. No other side effects were observed. Conclusions Considering the strong acaricidal activity of carvacrol in vitro and in vivo and the mild and transient local side effects, carvacrol shows potential as an acaricidal agent in the treatment of P. ovis in cattle.

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Evaluatie van twee intensieve behandelingsschema’s tegen Psoroptes ovis-schurft bij Belgisch witblauwe runderen op negen Vlaamse rundveebedrijven

Cited by 5 publications

References 6 publications

Resistance against macrocyclic lactones in Psoroptes ovis in cattle

Resistance against macrocyclic lactones in Psoroptes ovis in cattle

New insights into the use of a mite count reduction test for the detection of therapeutic acaricide efficacy in Psoroptes ovis in cattle

Acaricidal activity of plant-derived essential oil components against Psoroptes ovis in vitro and in vivo

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