Further evaluation of the efficacy of emamectin benzoate for treating Pseudocapillaria tomentosa (Dujardin 1843) in zebrafish Danio rerio (Hamilton 1822)

Abstract

Pseudocapillaria tomentosa is a pathogenic nematode parasite, causing emaciation and severe inflammatory lesions in the intestines in zebrafish Danio rerio (Hamilton 1822). Emamectin benzoate is commercially available analogue of ivermectin used for treating salmon for sea lice, under the brand name SLICE®, and we have used this for treating zebrafish with the P. tomentosa. Here, SLICE®, 0.2 per cent active emamectin benzoate, was used for oral treatments at 0.35 mg emamectin benzoate/kg fish/day for 14 days starting at 7 days post‐exposure (dpe). Another experiment entailed initiating treatment during clinical disease (starting at 28 dpe). Early treatment was very effective, but delaying treatment was less so, presumably due to inappetence in clinically affected fish. We evaluated emamectin benzoate delivered in water, using Lice‐Solve™ (mectinsol; 1.4% active emamectin benzoate) in two experiments. Application of four 24‐hr treatments, space over 7 days was initiated at 28 dpe at either 0.168 or 0.56 mg emamectin benzoate/L/bath, and both treatments completely eradicated infections. This was 3 or 10 times manufacture's recommended dose, but was not associated with clinical or histological side effects.

Review of diseases and health management in zebrafish Danio rerio (Hamilton 1822) in research facilities

“…Antiparasitic drugs typically used for nematodes, such as macrocyclic lactones, are effective for treating the infection. Emamectin, the ivermectin analogue used for treating sea lice, is effective as both an oral and bath treatment (Kent, Watral, Gaulke, & Sharpton, 2019). Eggs in the environment are killed by high levels of chlorine, iodine, UV, desiccation and heat (Kent, Watral, Villegas, & Gaulke, 2019).…”

Effects of emamectin benzoate on pharmacokinetic profiles, bioavailability, and serum biochemical indices in crucian carp (Carassius carassius) following oral administration with multiple dosage levels

“…Many literatures demonstrated the efficacy of EMB against Argulus in zebra fish ( Brachydanio rerio var ) ( 7 ), common carp ( Cyprinus flammans ) ( 8 ), koi carp ( Cyprinus carpio ) and goldfish ( Carassius auratus ) ( 9 ), endoparasitic monogenean in freshwater-reared largemouth bass ( Micropterus salmoides ) ( 10 ), ectoparasites in seabass ( Lates calcarifer ) ( 11 , 12 ), and sea lice in salmon ( salmon salar ) ( 13 , 14 ). The mechanism of EMB against fish parasites is to bind to GABA receptors and cause an increase in membrane chloride permeability, resulting in the paralyzation of parasites that then become ineffective ( 15 – 18 ).…”