Essential Oils and Their Bioactive Compounds in the Control of Gastrointestinal Nematodes of Small Ruminants

Background: Gastrointestinal nematodes are one of the major health and economic problem of sheep and goats in the world. The control of these nematodes is carried out conventionally with synthetic anthelminths, which favored the selection of gastrointestinal nematode (GIN) populations multiresistant to anthelmintics. The emergence of anthelmintic resistance has stimulated the search for new alternatives to control small ruminant GIN, standing out the use of plants and their bioactives compounds, such as essential oils (EO). The objective of this review was to present the main characteristics and anthelmintic activity of EO, their isolated compounds and drug delivery systems in the control of GIN.Review: Essential oils are a complex blend of bioactive compounds with volatile, lipophilic, usually odoriferous and liquid substances. EO are composed of terpenes, terpenoids, aromatic and aliphatic constituents. EO has various pharmacological activities of interest in preventive veterinary medicine such as antibacterials, antifungals, anticoccicids, insecticides and anthelmintics. In vitro and in vivo tests are used to validate the anthelmintic activity of EO on GIN. In vitro tests are low cost screening tests that allow the evaluation of the anthelmintic activity of a large amount of bioactive compounds on eggs, first (L1) and third stage larvae (L3), and adult nematodes. The antiparasitic effect of EO is related to its main compound or to the interaction of the compounds. These bioactive compounds penetrate the cuticle of the nematodes by transcuticular diffusion, altering the mechanisms of locomotion, besides causing cuticular lesions. Following in vitro evaluation, the acute and sub-chronic toxicity test should be performed to assess the toxicity of the bioactive compounds and to define the dose to be used in in vivo tests. In vivo tests are more reliable because the anthelmintic effectiveness of bioactive compounds is evaluated after the metabolization process. The metabolization process of the bioactive compounds can generate metabolites that exhibit or not anthelmintic effectiveness. The in vivo tests assessing the anthelmintic effectiveness of bioactive compounds in sheep and goats are the fecal egg count reduction test and the controlled test.  OE promoted reduction of egg elimination in faeces which may be related to cuticular and reproductive alterations in GIN, and reduction of parasite burden in in vivo tests. Due to the promising results obtained with OE in the in vivo tests, interest has been aroused in using nanotechnology as an alternative to increase the bioavailability of OE and consequently, potentializing its anthelmintic effect, reducing the dose and  toxicity of the biocompounds. In addition to nanotechnology, the isolation and chemical modification of compounds isolated from OE have been employed to obtain new molecules with anthelmintic action and understand the mechanism of action of EO on the small ruminant GIN.Conclusion: The use of EO and their compound bioactive in the control of resistant populations of GIN is a promising alternative. The adoption of strategies in which natural products can replace synthetic anthelmintics, such as in dry periods and use synthetic anthelmintics in the rainy season when the population in refugia in the pasture is high, thus reducing the dissemination of GIN resistant populations. As perspective, the evaluation of pharmacokinetics and pharmacodynamics of these natural products should be performed so that one defines treatment protocols that optimize the anthelmintic effect

In vitro effects of Coriandrum sativum, Tagetes minuta, Alpinia zerumbet and Lantana camara essential oils on Haemonchus contortus

Phytotherapy can be an alternative for the control of gastrointestinal parasites of small ruminants. This study evaluated the efficacy of Alpinia zerumbet, Coriandrum sativum, Tagetes minuta and Lantana camaraessential oils by two in vitro assays on Haemonchus contortus, an egg hatch test (EHT) and larval development test (LDT). No effect was observed for L. camara in the EHT. A. zerumbet, C. sativum and T. minuta essential oils exhibited a dose-dependent effect in the EHT, inhibiting 81.2, 99 and 98.1% of H. contortus larvae hatching, respectively, at a concentration of 2.5 mg mL-1. The effective concentration to inhibit 50% (EC50) of egg hatching was 0.94, 0.63 and 0.53 mg mL-1 for A. zerumbet, C. sativum and T. minuta essential oils, respectively. In LDT, L. camara, A. zerumbet, C. sativum and T. minuta at concentration of 10 mg mL-1 inhibited 54.9, 94.2, 97.8 and 99.5% of H. contortus larval development, presenting EC50 values of 6.32, 3.88, 2.89 and 1.67 mg mL-1, respectively. Based on the promising results presented in this in vitro model, it may be possible use of these essential oils to control gastrointestinal nematodes. However, their anthelmintic activity should be confirmed in vivo

Dermatofitose canina causada pelo fungo antropofílico Trichophyton tonsurans: Relato de caso

Dermatophytoses is a skin disease caused by fungi that deserves attention for its high incidence in clinical small animal and animal and human health importance because it can be transmitted from animals to humans or from humans to animal. This study aimed to report a case of canine dermatophytoses caused by anthropophilic species of dermatophyte, involving clinical and laboratory diagnosis. A dog, female, York Shire, with about three years of age, revealed generalized alopecia and therefore was referred for a consultation, in which the clinical suspicion was dermatophytoses. Skin scales and hair for laboratory tests were collected. On direct examination, there was no evidence the presence of fungal structures. However, fungal culture of the clinical specimen showed the growth of colonies of Trichophyton tonsurans. The therapy with itraconazole, an antifungal broad spectrum, was effective. This case report emphasizes the need to conduct laboratory exams in the presence of suspicious lesions of dermatophytoses for identification of the etiologic agent and subsequently adoption of control and prevention measures of this disease, which presents a complex epidemiological chain of transmissionA dermatofitose é uma enfermidade cutânea de origem fúngica que merece destaque por sua elevada incidência na clínica de pequenos animais e importância na saúde animal e humana, pois pode ser transmitida do animal para o homem ou do homem para o animal. Este trabalho teve como objetivo relatar um caso de dermatofitose canina causado por uma espécie antropofílica de dermatófito, envolvendo o diagnóstico clínico e laboratorial. Uma cadela, da raça York Shire, com aproximadamente três anos de idade, apresentava alopecia generalizada e, por isso, foi encaminhada para uma consulta, na qual a suspeita clínica foi de dermatofitose. Foram coletadas escamas de pele e pêlos para realização de exames laboratoriais. No exame direto, não foi evidenciada a presença de estruturas fúngicas. Contudo, na cultura fúngica do espécime clínico evidenciou-se o crescimento de colônias de Trichophyton tonsurans. A terapia com itraconazol, um antifúngico de amplo espectro, foi efetiva. O presente relato de caso ressalta a necessidade de realização de exames complementares laboratoriais na presença de lesões suspeitas de dermatofitose, para identificação do agente etiológico e posterior adoção medidas de controle e prevenção dessa enfermidade que apresenta uma complexa cadeia epidemiológica de transmissão

Anthelmintic activity of Cymbopogon citratus against Haemonchus contortus

Parasitic nematodes are of major economic importance in livestock. An alternative for the control of parasites is phytotherapy. This study evaluated the efficacy of Cymbopogon citratus decoction (CcD), C. citratus essential oil (CcEo) and citral against Haemonchus contortus using in vitro egg hatch test (EHT) and larval development test (LDT) and an in vivo test using a Meriones unguiculatus (gerbil) model. The effect of 800 mg/kg CcEo was evaluated in gerbils that had been artificially infected with 5,000 third-stage H. contortus larvae. The effective concentrations required to inhibit 50% (EC50) of egg hatching were 0.46, 0.14 and 0.13 mg/mL for CcD, CcEo and citral, respectively. The EC50 values in the LDT were 5.04, 1.92 and 1.37 mg/mL for CcD, CcEo and citral, respectively. H. contortus population in the group treated with C. citratus essential oil was reduced by 38.5% (P< 0.05) in comparison to the control group. These results suggest that it may be possible to use C. citratusessential oil to control of H. contortus parasite of small ruminant