Efficacy and safety assessment of a water-soluble formulation of fluralaner for treatment of natural Ornithonyssus sylviarum infestations in laying hens

Abstract

BackgroundNorthern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago, 1877), infestations can stress birds, impairing welfare and causing substantial economic losses. A study was undertaken to determine the efficacy of an ectoparasiticide solution (fluralaner) for oral administration in the treatment of mite-infested hens.MethodsClinically healthy, naturally mite-infested laying hens (n = 132), approximately 32 weeks of age, were ranked by Day -9 mite vent counts and randomized among 12 study pens, each to hold one of four treatment groups. Three groups received fluralaner-medicated water by oral gavage at dose rates of 0.25, 0.5 or 1.0 mg/kg on Days 0 and 7; one group was an untreated control (three pens for each group). Five naturally infested untreated birds were included in each pen to act as mite-infested source birds. Thus each pen, treated and control, had six non-source birds for assessment of efficacy, plus five source birds to provide ongoing challenge. Primary efficacy assessments were based on mean O. sylviarum vent counts from non-source birds in the control and treated group pens on Days 1, 2, 6, 8, 12, 15, 19, 22 and 26.ResultsSource-birds maintained infestations throughout the study, validating the challenge to study birds. On Days 1 through 22, mean control group mite counts were significantly greater than those of the treated groups (P ≤ 0.013). Relative to the control group, mean O. sylviarum counts were reduced by at least 90% from Day 6 through Days 19, 22 and 22 in the fluralaner 0.25, 0.5 and 1.0 mg/kg groups, respectively. On Day 19, mean mite counts were lower in the 0.5 and 1.0 mg/kg groups compared with the 0.25 mg/kg group (P ≤ 0.018), and in the 1.0 mg/kg compared with the 0.5 mg/kg group (P = 0.014). There were no adverse events in treated birds.ConclusionsA fluralaner solution administered twice by gavage to laying hens with a one-week between-treatment interval was safe and effective in quickly controlling O. sylviarum infestations despite continuous challenge from infested birds. By eliminating mites, this fluralaner solution has the potential to improve bird health and productivity, and to eliminate the burden of topical pesticide application.

Lethal and sublethal effects of fluralaner on the two‐spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae)

“…Fluralaner has high activity towards parasitic mites on animals, such as demodectic mite ( Demodex sp.) on Shih‐Tzu Canis lupus dingo Meyer and red‐handed tamarins Saguinus midas , poultry red mite Dermanyssus gallinae in birds, and northern fowl mite Ornithonyssus sylviarum in laying hens . In addition, fluralaner also exhibits high activity towards the phytophagous mite of TSSM and has been shown to bring about 100% mortality at a concentration of 3.1 mg L −1 against fipronil‐resistant (∼ 500 mg L −1 ) TSSM …”

“…on Shih-Tzu Canis lupus dingo Meyer 18 and red-handed tamarins Saguinus midas, 19 poultry red mite Dermanyssus gallinae in birds, 20 and northern fowl mite Ornithonyssus sylviarum in laying hens. [21][22][23] In addition, fluralaner also exhibits high activity towards the phytophagous mite of TSSM and has been shown to bring about 100% mortality at a concentration of 3.1 mg L −1 against fipronil-resistant (∼ 500 mg L −1 ) TSSM. 24 As is well-known, research on the toxicological effects of fluralaner towards TSSM will enhance the ability to design and execute mite management programs.…”

Fluralaner as a novel treatment for sarcoptic mange in the bare-nosed wombat (Vombatus ursinus): safety, pharmacokinetics, efficacy and practicable use

“…On this basis, we report that fluralaner is competitive in its cost relative to moxidectin, particularly under the current APVMA permit [ 63 ]. Albeit beyond the scope of this study, inclusion of the additional labour costs involved with weekly applications of moxidectin for 12–15 weeks would further skew the results in favour of fluralaner use [ 80 ]. Similarly, in a resource-limited setting such as this, treatment effort is often of equal importance to price, and the low dosing requirement of fluralaner renders it by far the most effort-efficient option overall.…”

Use of oral fluralaner (Bravecto) to successfully manage adult‐onset generalised demodicosis in a silver fox (Vulpes vulpes)

“…Anecdotal evidence suggests that these products have a high efficacy rate at the doses labelled for flea and tick prevention against parasites including Demodex species, Sarcoptes species, Otodectes species, Cheyletiella species, Lynxacarus species and various poultry mites 2 12–15. Use in off‐label hosts including poultry, pigs, rabbits, hedgehogs and wildlife suggest this drug class has a wide margin of safety 16–24. Consideration for use in human beings using porcine models of disease may lead to promising breakthroughs in control of parasitic infections in endemic regions of the world 25.…”