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

Resistencia anti-helmintica em ovinos e caprinos

Chapitre 3International audienc

ANTHELMINTIC RESISTANCE TO BENZIMIDAZOLE IN GASTROINTESTINAL NEMATODES FROM SMALL RUMINANTS OF SEMI-ARID BRAZILIAN NORTHEAST RESISTÊNCIA AOS ANTI-HELMÍNTICOS BENZIMIDAZÓIS EM NEMATÓIDES GASTRINTESTINAIS DE PEQUENOS RUMINANTES DO SEMIÁRIDO NORDESTINO BRASILEIRO

Resistance to benzimidazole anthelmintics is reported as an old and persistent problem in many parts of the world. Resistance development depends on the presence of resistance promoters and there are operational, genetic and bioecological factors. The objective of this work was to determine the prevalence of benzimidazole resistance and to study some variables associated with resistance development in small ruminant farms in the Brazilian northeastern semi-arid area. The work was accomplished in 25 sheep and goat farms in Limoeiro do Norte, Palhano, Jaguaruana, Itaiçaba, Aracati, Alto Santo, Morada Nova and Jaguaribe municipalities, in the state of Ceará, Brazil. The procedure used to detect anthelmintic resistant nematodes was the fecal egg count reduction test. In addition, a questionnaire about management practices, infrastructure, anthelmintic usage, flocks sanitary state and veterinary assistance was applied. Data were analyzed using RESO statistical program. The questionnaires were analyzed using Spearman correlation and the simple GLM. In sheep farms, the prevalence of benzimidazole resistance was 88% and in goat farms, it was 87.5%. In sheep and goats farms, Haemonchus spp was the most prevalent genus, followed by Trichostrongylus spp and Oesophagostomum spp. Among variables studied, treatment in the dry season was statistically significant (P = 0.03), pasture rotation was not significant (P = 0.17) but has a predictable value in resistance development. <br /><br />KEY WORDS: Associated factors, benzimidazole, Ceará, resistance development.<br /> A resistência a anti-helmínticos benzimidazóis é relatada como um antigo e persistente problema em diversas partes do mundo. O desenvolvimento da resistência depende da presença de promotores, os quais podem ser fatores operacionais, genéticos e bioecológicos. O objetivo do presente estudo foi determinar a prevalência da resistência a anti-helmínticos benzimidazóis e estudar algumas variáveis associadas ao desenvolvimento da resistência em fazenda de criações de pequenos ruminantes numa área semiárida do Nordeste brasileiro. O trabalho foi realizado em 25 fazendas de ovinos e caprinos localizadas nos municípios de Limoeiro do Norte, Palhano, Jaguaruana, Itaiçaba, Aracati, Alto Santo, Morada Nova e Jaguaribe, no estado do Ceará, Brasil. O procedimento usado para detectar nematoides resistentes a anti-helmínticos foi o teste de redução na contagem de ovos nas fezes. Além disso, aplicou-se um questionário sobre práticas de manejo, infraestrutura, utilização de anti-helmínticos, estado sanitário do rebanho e assistência veterinária. Analisaram-se os dados mediante a utilização do programa estatístico RESO e os questionários por meio da correlação de Spearman e  GLM simples. Nas fazendas de ovinos, a prevalência da resistência a benzimidazóis foi de 88% e em fazendas de caprinos de 87,5%. Em fazendas de ovinos e caprinos, Haemonchus spp. foi o gênero mais prevalente, seguido de Trichostrongylus spp. e Oesophagostomum spp. Das variáveis estudadas, o tratamento na estação seca mostrou-se estatisticamente significativo (P=0,03), a rotação de pastagem não significativa (P=0,17), porém apresentando um valor preditivo do desenvolvimento da resistência.<br /><br />PALAVRAS-CHAVES: Benzimidazóis, Ceará, desenvolvimento da resistência, fatores associados.<br /&gt

Epidemiological survey of Lutzomyia longipalpis infected by Leishmania infantum in an endemic area of Brazil

The objective of this study was to perform an epidemiological survey to determine the areas at risk of visceral leishmaniasis through the detection and quantification of natural infection by Leishmania infantum in Lutzomyia longipalpis. The sandflies were captured between February 2009 and January 2010, at 21 sites in four regions of the Fortaleza municipality. Samples were screened for the presence of Leishmania DNA by Real Time PCR (qPCR), amplification of kDNA minicircle sequence. Out of the 123 pools of analyzed sandflies, 45 were positive for L.infantum, and the minimum infection rate was 3.7%. In the north, south, east and west regions, the pool screen assay predicted sand-fly infection prevalence of 3.4%, 4.7%, 4.9% and 8.4%, respectively. The parasite load ranged from 2.45 ± 0.96 to 2,820,246 ± 106,072. No statistical differences were found with respect to the frequency of sand-fly infection between the regions (P=0.3014), seasons (P = 0.3906) or trap locations (P = 0.8486). Statistical differences were found with respect to the frequency of sand-fly infection between the two seasons only in the west region (P=0.0152). The qPCR was able to detect and quantify L. infantum in L. longipalpis, therefore succeeding in identifying the areas of greatest risk of VL transmission

Atividade predatória do fungo Monacrosporium thaumasium contra o nematóide Haemonchus contortus, após passagem pelo trato gastrintestinal de caprinos

Conídios de Monacrosporium thaumasium foram administrados por via oral a caprinos para verificar a viabilidade desse fungo nematófago após passagem pelo trato gastrintestinal. Foram realizadas amostragens de fezes de 18 a 30 horas após inoculação. Constatou-se crescimento do fungo e atividade predatória contra Panagrellus spp em placas confeccionadas com fezes coletadas 21 e 24 horas após a inoculação. Houve uma redução média de 79,24% no número de larvas infectantes de Haemonchus contortus provenientes de coproculturas preparadas com fezes coletadas 24 horas após a administração do fungo. O fungo M. thaumasium manteve atividade predatória sobre H. contortus, após passagem através do trato gastrintestinal de caprinos

In vitro efficacy of Coriandrum sativum, Lippia sidoides and Copaifera reticulata against Leishmania chagasi

Abstract The increased incidence of visceral leishmaniasis (VL) in Brazil is due to a lack of effective disease control measures. In addition to that, no effective treatment exists for canine VL in response to synthetic drugs. Thus, the objective of this study was to evaluate the effect of the essential oils of Coriandrum sativum and Lippia sidoides, and oleoresin from Copaifera reticulata, on Leishmania chagasi promastigotes and amastigotes. We also examined the toxicity of these treatments on the murine monocyte cell line RAW 264.7. To determine the IC50 a MTT test (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed on promastigotes, and an in situ ELISA assay was conducted on amastigotes. Here, we demonstrate that oleoresin from C. reticulata was effective against both promastigotes (IC50 of 7.88 µg.mL -1 ) and amastigotes (IC50 of 0.52 µg.mL -1 ), and neither of the two treatments differed significantly (p > 0.05) from pentamidine (IC50 of 2.149 µg.mL -1 ) and amphotericin B (IC50 of 9.754 µg.mL -1 ). Of the three plant oils tested, only oleoresin showed no toxicity toward monocyte, with 78.45% viability after treatment. Inhibition of promastigote and amastigote growth and the lack of cytotoxicity by C. reticulata demonstrate that oleoresin may be a viable option for analyzing the in vivo therapeutic effects of leishmanicidal plants Keywords: Leishmanicidal plants, oils, cytotoxicity, amastigotes, promastigotes, Leishmania chagasi. Resumo O aumento na incidência da Leishmaníase Visceral (LV) no Brasil deve-se à ineficácia das medidas de controle da doença. Além disso, não há tratamento efetivo para LV canina com drogas sintéticas. Assim, o objetivo deste trabalho foi avaliar o efeito dos óleos essenciais de Coriandrum sativum e de Lippia sidoides e do óleo-resina de Copaifera reticulata sobre promastigotas e amastigotas de Leishmania chagasi e analisar o grau de toxicidade sobre células monocíticas murinas RAW 264.7. Para determinar a CI50 sobre promastigotas foi usado teste MTT (brometo de 3-[4,5-dimetiltiazol-2-il]-2,5-difeniltetrazólio) e sobre amastigotas foi realizado imunoensaio in situ pela técnica de ELISA. Os resultados obtidos comprovaram que o óleo-resina de C. reticulata foi o mais eficaz contra as formas promastigotas (CI50 de 7,88 µg.mL -1 ) e amastigotas (CI50 de 0,52 µg.mL -1 ) e em nenhum dos dois testes diferiu do controle pentamidina que obteve CI50 de 2,149 µg.mL -1 , no teste sobre promastigotas, e anfotericina B que obteve CI50 de 9,754 µg.mL -1 , nos testes com amastigotas (p > 0.05). Quanto à citotoxicidade apenas o óleo-resina não apresentou toxicidade com 78,45% de monócitos viáveis. Os resultados obtidos sobre promastigotas e amastigotas e a ausência de citotoxicidade do óleo-resina de C. reticulata evidenciam que este óleo-resina pode ser viável para a análise de seus efeitos terapêuticos em testes in vivo

Ecology of Lutzomyia longipalpis and Lutzomyia migonei in an endemic area for visceral leishmaniasis

The main vector for visceral leishmaniasis (VL) in Brazil is Lutzomyia longipalpis. However, the absence of L. longipalpis in a region of autochthonous VL demonstrates the participation of other species in the transmission of the parasite. Studies conducted in La Banda, Argentina, and São Vicente Férrer, Pernambuco State, Brazil, have correlated the absence of L. longipalpisand the presence of L. migonei with autochthonous cases of VL. In São Vicente Férrer, Pernambuco, there was evidence for the natural infection of L. migonei with Leishmania infantum chagasi. Thus, the objective of this work was to assess the ecology of the sand flies L. longipalpis and L. migonei in Fortaleza, an endemic area for VL. Insect capture was conducted at 22 sampling points distributed across four regions of Fortaleza. In total, 32,403 sand flies were captured; of these, 18,166 (56%) were identified as L. longipalpis and 14,237 (44%) as L. migonei. There were significant density differences found between the vectors at each sampling site (indoors and outdoors) (p <0.0001). These findings confirm that L. migonei and L. longipalpis are distributed throughout Fortaleza, where they have adapted to an indoor environment, and suggest that L. migonei may share the role as a vector with L. longipalpis in the transmission of VL in Fortaleza