The sensitivity of Demodex canis (Acari: Demodicidae) to the essential oil of Melaleuca alternifolia - an in vitro study.

Rita De Cássia Da Silva Machado Neves Neves,Ana Maria Reis Ferreira,Luciano Antunes Barros,Shihane Mohamad Costa Mendes,Lúcia Aparecida De Fátima Mateus,Juliana Da Silva Leite,Vany Perpétua Ferraz,Thalita Irineu De Souza Werneck De Assis De Amorim Amorim

doi:10.1590/s1984-29612020059

Abstract

The essential oil of the Melaleuca alternifolia (Maiden & Betche) (tea tree oil) has been effective in previous studies, in the treatment of infestation by Demodex mites in humans. The present study aimed at evaluating the in vitro acaricidal effect of this herbal medicine on Demodex canis. For the parasitological examination, samples were collected from a dog's skin and examined using optical microscopy. Only samples with intact mites and with evident movement of chelicerae and tarsi were selected. Twenty-one samples were tested with the oil, in seven different concentrations: 100%; 50%; 25%; 12.5%; 6.25%; 5.0% and 3.13%. Three samples were tested with the positive control amitraz, and three with the negative control neutral shampoo. The interval between the time the solution was added and the moment the movement of the last mite ceased defined the survival time in the sample. By comparing the times at different concentrations and controls, the results showed that the higher the concentration of the oil, the more quickly its lethal effect occurred, and that the survival times in the controls were longer than in the different concentrations of melaleuca oil.

Highlights

Mites of the genus Demodex are commensal on the skin of mammals (Patra et al, 2019) causing severe inflammatory skin disease when a population of these parasites exceeds the point of equilibrium
The pathogenic role of these mites is well documented in dogs, in which Demodex canis Leydig 1859 causes demodicosis (Jarmuda et al, 2012), which usually requires several months of treatment to achieve clinical resolution (Mueller et al, 2012)
Some orthodox and some off-label, such as ivermectin, doramectin, and moxidectin, subsequently became available for use as more convenient forms of treatment in veterinary medicine (Delayte et al, 2006) and continues to be used in small animal clinics, there have been some reports of adverse reactions (Singh et al, 2011; Perego et al, 2019)

Summary

Introduction

Mites of the genus Demodex are commensal on the skin of mammals (Patra et al, 2019) causing severe inflammatory skin disease when a population of these parasites exceeds the point of equilibrium. The pathogenic role of these mites is well documented in dogs, in which Demodex canis Leydig 1859 causes demodicosis (Jarmuda et al, 2012), which usually requires several months of treatment to achieve clinical resolution (Mueller et al, 2012). In many countries, the gold-standard treatment for demodicidosis has consisted of the application of an aqueous dilution of amitraz, a product of the formamidine group (Adams, 2003). The acaricidal activity of amitraz is based on disrupting the transmission of nerve impulses, because it is an antagonist at the octopamine receptor level (Hugnet et al, 1996; Rhodes, 2004). Some orthodox and some off-label, such as ivermectin, doramectin, and moxidectin, subsequently became available for use as more convenient forms of treatment in veterinary medicine (Delayte et al, 2006) and continues to be used in small animal clinics, there have been some reports of adverse reactions (Singh et al, 2011; Perego et al, 2019)

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