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Los ciatostominos son los principales nematodos gastrointestinales (NGI) que afectan a los caballos, su control se basa en el uso de antihelmínticos (AH); sin embargo, a nivel mundial se ha reportado resistencia a los AH. Por tanto, es necesario conocer la susceptibilidad de los NGI a los AH para tomar decisiones de tratamiento eficiente. Por tal motivo, el objetivo de este estudio fue evaluar la eficacia de lactonas macrocíclicas en poblaciones de NGI mediante la prueba de reducción de huevos en heces y determinar el periodo de reaparición de huevos (PRH). Se utilizaron 58 caballos en 7 unidades equinas de Tuxpan, Veracruz, se aplicó un cuestionario para conocer la situación general de las cuadras y tratamiento de cada unidad. Al día cero se colectaron heces de forma individual para determinar el número de huevos en las heces mediante la técnica de McMaster. Los animales que resultaron positivos a ≥100 huevos por gramo de heces (hph) se conformaron en dos grupos. El grupo tratado se le aplicó ivermectina (IVM) a razón de 0.2 mg/kg de peso vivo y el grupo control no recibió tratamiento. Se tomaron muestras a los días 14, 42 y 56 días post-tratamiento (PT) y se determinaron los hgh. Se observó que el 83.3 % de los caballos fueron positivos a NGI y el 1.7% a otros nematodos. En seis de las unidades se encontró 100% de reducción en el conteo de huevos y solo una unidad resultó sospechosa a resistencia a la IVM. Así mismo, el PRH se redujo a 42 días. Se concluye a pesar de que la IVM continúa siendo eficaz para el control de NGI en la mayoría de las unidades evaluadas, sin embargo, el PRH se ha reducido.

Ivermectin belongs to the group of avermectins, a group of macrocyclic lactones produced by Streptomyces avermitilis, this drug is widely used in the treatment of endoparasitoses and ectoparasitosis in different species of mammals around the world. Based on this need to develop an adequate sanitary management of fish farms and the therapeutic importance of macrocyclic lactones, this study aimed to evaluate the clinical safety of ivermectin administered orally as part of the feed for Nile tilapia (O. niloticus). For this, 56 tilapias (O. niloticus), ±100g, were placed in 7 aquariums (n=8) with a capacity of 100 L of water, supplied with running water devoid of chlorine, with the following treatments being preserved: T0 (Control, untreated), T1 and T2 (treated with 125 and 625µg/kg-1 of ivermectin, respectively). Blood samples were collected for hemogram, leukogram and evaluation of serum biochemical parameters, in addition to organs such as spleen, liver and kidneys (cranial and caudal) for somatic evaluation. The results admired an increase in serum levels of ALT, AST and glycemia, a reduction in cholesterol and triglyceride values at the highest dose, in addition to a decrease in total protein levels and liver somatic analysis. There was no change in hematological parameters, while the leukocyte profile indicated a significant increase in total leukocytes in treated tilapia with lymphocytosis and neutrophilia.. Therefore, treatment with high doses of ivermectin can harm the health of Nile tilapia, requiring additional studies to establish safe therapeutic protocols for these animals. [ABSTRACT FROM AUTHOR]

As helmintoses gastrintestinais em ovinos são o principal fator que interfere na produção e criação destes animais e se não tratada de forma adequada, pode levar ao desenvolvimento de resistência, resultando em prejuízos ao produtor. Deste modo, o trabalho tem por objetivo, determinar a atividade anti-helmíntica das formulações contendo moxidectina e ivermectina em ovinos naturalmente infectados por nematódeos gastrintestinais de propriedades rurais pertencentes à região de Umuarama-PR, através da realização de testes de redução na contagem de ovos por grama de fezes (OPG). Em duas propriedades avaliadas, ambas as formulações demonstraram ineficiência na atividade antihelmíntica em ovinos.

Background. Macrocyclic lactones (ML) are effective in controlling endo- and ectoparasites in livestock. ML, specially ivermectin and moxidectin, have a typical pharmacokinetic profile of lipophilic molecules with slow degradation and when administered to livestock are excreted in the faeces almost unaltered. ML released into the environment, can cause lethal and sublethal effects on dung beetles (DB). Objective. To document the main scientific contributions of our research group to the awareness of the adverse effect of ML on DB associated with livestock environments under grazing systems. Methodology. The compilation of scientific articles from the studies carried out by a research group in the first 50 years of the FMVZ-UADY was carried out. Results. The studies have shown that ML (IVM-1%, IVM-3.15%, MOX-10%) in dung from cattle treated with injectable formulations had a sublethal effect on DB. For the species Canthon indigaceus chevrolati dung from cattle treated with injectable formulations of IVM (1% and 3.15%) and MOX (1% and 10%) do not produce lethal and sublethal effects. Faecal ivermectin residues may induce changes in attraction of some neotropical DB species to dung pats. Implications. Current ML application methods may have negative effects on the environmental services provided by dung beetles, and therefore need to be modified to minimize any impacts they might have on these vital members of tropical livestock systems. Conclusions. The review shows the adverse effects of ML on DB in the Mexican tropics; however, for the C. i. chevrolati, dung from cattle treated with IVM and MOX, do not produce lethal and sublethal effects, which suggests some type of tolerance

El objetivo del presente estudio fue cuantificar la ivermectina eliminada en la materia fecal del ganado bovino, la cual fue detectada mediante la técnica de Cromatografía Líquida de Alta Resolución (CLAR), en la granja experimental Tunguavita, en la vereda Salitre de la ciudad de Paipa (Boyacá). Se experimentó en 10 novillas de diferentes razas y pesos con ivermectina comercial al 1% en una dosis de 0,2 mg/kg de peso vivo, por vía subcutánea en una sola aplicación. Se observó que al segundo día de haber aplicado el antiparasitario se obtuvo la concentración más alta (87.6%), y a los 20 días, la más baja (0,17%); es decir, la concentración de ivermectina fue disminuyendo, aproximadamente, en 0.0535 ppm por día. No se encontraron diferencias significativas entre razas y pesos de los animales. Los resultados de este estudio muestran la presencia de ivermectina en las heces del ganado bovino, presencia que genera un impacto ambiental negativo frente a la entomofauna coprófaga, encargada de la degradación de la materia fecal, ya que las diferentes concentraciones de ivermectina continúan con su función insecticida al ser eliminadas en la materia fecal. De otro lado, se determinó que cierta parte del desparasitante está siendo asimilado por diferentes órganos internos del individuo, por lo tanto, no se eliminan en su totalidad.

O amplo espectro de ação dos endectocidas e a praticidade de aplicação das suas formulações pour-on são fatores que têm estimulado uma maior frequência de utilização destes produtos na criação de bovinos. Neste estudo, avaliou-se a eficácia anti-helmíntica da ivermectina, administrada via pour-on, 500mcgkg-1, contra nematódeos de bovinos provenientes de diferentes rebanhos. Foram adquiridos 12 bezerros de cada um dos quatro rebanhos selecionados. Todos os 48 bezerros utilizados apresentavam médias de ovos por grama de fezes (OPG) maiores que 500, considerando-se três contagens consecutivas. Na sequencia, os animais de cada rebanho foram divididos em dois grupos de seis bovinos cada, sendo um tratado com ivermectina 500mcgkg-1 via pour-on e outro mantido como controle. Quatorze dias depois do tratamento, os bovinos foram submetidos à eutanásia para contagem de endoparasitas. A ivermectina demonstrou resultados nulos de eficácia contra H. placei nos quatro rebanhos. Contra C. punctata, tal formulação teve eficácia nula nos rebanhos provenientes de Jaboticabal,SP, e de Formiga,MG, e eficácias de 75,8% e 58,4% nos rebanhos provenientes de São José do Rio Pardo,SP, e de São Sebastião do Paraíso,MG, respectivamente. Valores de eficácia de 94,2% (Jaboticabal), 0,0% (São José do Rio Pardo), 94,2% (Formiga) e 39,2% (São Sebastião do Paraíso) foram detectados contra O. radiatum. Com base nos resultados encontrados, pode-se concluir que as quatro populações de Haemonchus placei e de Cooperia punctata avaliadas foram resistentes à ivermectina, administrada via pour-on, 500mcgkg-1. Foram observadas cepas de Oesophagostomum radiatum resistentes à ivermectina em dois dos quatro rebanhos testados.

Haemonchus contortus is one of the most common and economically significant causes of disease in small ruminants worldwide, and the control programs of parasitic nematodes - including H. contortus - rely mostly on the use of anthelmintic drugs. The consequence of the use of this, as the sole sanitary strategy to avoid parasite infections, was the reduction of the efficacy of all chemotherapeutic products with a heavy selection for resistance. The widespread of anthelmintic resistance and the difficulty of its early diagnosis has been a major concern for the sustainable parasite management on farms. The objective of this research was to determine and compare the ivermectin (IVM) and moxidectin (MOX) effect in a selected field strain of H. contortus with a known resistance status, using the in vitro larval migration on agar test (LMAT). Third stage larvae of the selected isolate were obtained from faecal cultures of experimentally infected sheep and incubated in eleven increasing diluted concentrations of IVM and MOX (6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072 and 6144µg/mL). The dose-response sigmoidal curves were obtained using the R² value of >0.90 and the lethal concentration (LC50) dose for the tested anthelmintic drugs using a four-parameter logistic model. The LC50 value for MOX was significantly lower than IVM (1.253µg/mL and 91.06µg/mL), identifying the H. contortus isolate as considerably less susceptible to IVM compared to MOX. Furthermore, the LMAT showed a high consistency (pHaemonchus contortus é uma das causas mais comuns e economicamente significativas de doença em produções de pequenos ruminantes em todo o mundo, e os programas de controle de parasitas nematoides - incluindo H. contortus - baseiam-se principalmente no uso de drogas anti-helmínticas. A consequência da utilização desses compostos, como sendo a única estratégia sanitária para evitar infecções por parasitas, tem sido a redução da eficácia de todos os produtos quimioterápicos, selecionando fortemente para resistência. O desenvolvimento generalizado da resistência anti-helmíntica e a dificuldade de seu diagnóstico precoce têm sido uma grande preocupação para o manejo sustentável de parasitas no campo. O objetivo desta pesquisa foi determinar e comparar o efeito da ivermectina (IVM) e da moxidectina (MOX) em um isolado de campo selecionado de H. contortus com um estado de resistência conhecido, utilizando o teste in vitro de migração de larvas em ágar (LMTA). Larvas de terceiro estágio de um isolado de H. contortus selecionado foram obtidas a partir de culturas de fezes de ovinos infectados experimentalmente e incubadas em onze concentrações diluídas crescentes de IVM e MOX (6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072 e 6144µg/mL). As curvas sigmoides de dose-resposta foram obtidas utilizando o valor de R² >0,90 e a dose de concentração letal (CL50) para as drogas anti-helmínticas testadas, utilizando um modelo logístico de quatro parâmetros. O valor de CL50 para MOX foi significativamente menor do que para IVM (1,253µg/mL e 91,06µg/mL), identificando o isolado de H. contortus como consideravelmente menos suscetível à IVM em comparação à MOX. Além disso, o LMTA mostrou uma alta consistência (p

This study was conducted in the grasslands of the Department of Casanare, seeking to determine the degree of anthelmintic susceptibility or resistance against macrocyclic lactones in small populations of Strongylus in this region of the country. Samples were taken from four municipalities in the department: Aguazul, Paz de Ariporo, Maní and El Yopal, between June, 2006 and April, 2007, where ten fresh fecal samples were collected in each municipality, directly from the field and in a completely random way. The samples were processed using the MacMaster coprological technique, thus determining the highest count of fecal epg by municipality. L3 larvae were extracted from each of the six samples with the highest count of fecal epg through the coprological and Baermann-Wetzel tests with which the Larvae Development Analysis (LDA) test was run, detecting Small Strongylus highly susceptible to the action of macrocyclic lactones (ivermectin).

Eighty-four half-blood Gir × Holstein (F1) calves aged six months who were naturally infected by gastrointestinal helminths and maintained in rotational grazing received different anthelmintic treatments. Group A received anthelmintics according to the usual management in the property (eight treatments, seven including a macrocyclic lactone agent). Group B received strategic treatment (ivermectin 3.15%) at the beginning and at the end of the rainy period. Eggs per gram of feces (EPG) counts and genus of larvae from fecal cultures were determined on a monthly basis from April 2002 to December 2003. There was no significant reduction (p > 0.05) in EPG counts in any group after anthelminthic treatment, and the larvae in fecal cultures observed were Cooperia, Haemonchus, Oesophagostomum and a few Trichostrongylus. Cooperia was the most prevalent genus in the first four months of the experiment and Haemonchus in the following months. In 2003, tracer calves were introduced onto the pastures monthly and they showed high nematode burden many times throughout the year, and Cooperia punctata and Haemonchus contortus were the main species identified. The results suggest that there is anthelminthic resistance in this farm, mainly to macrocyclic lactones, and the development of immunity by crossbred animals was vital to reduce nematode burden.Oitenta e quatro bezerras meio sangue Gir × holandês (F1) com seis meses de idade, naturalmente infectadas por helmintos gastrintestinais e mantidas em pastejo rotacionado receberam diferentes tratamentos anti-helmínticos. O grupo A recebeu anti-helmínticos segundo manejo empregado na propriedade (oito tratamentos, sete com produtos à base de lactonas macrocíclicas). O grupo B recebeu tratamento estratégico (ivermectina 3,15%) no inicio e final de período chuvoso. Mensalmente, no período de abril de 2002 a dezembro de 2003, foram realizadas contagens de ovos por grama de fezes (OPG) e coproculturas. Não houve redução significativa (p > 0,05) nas contagens de OPG em nenhum dos grupos após os tratamentos anti-helmínticos, e as larvas encontradas na coprocultura foram Cooperia, Haemonchus, Oesophagostomum e poucos Trichostrongylus, com predominância de Cooperia nos quatro meses iniciais e Haemonchus nos meses seguintes. No ano de 2003, bezerros traçadores foram alocados mensalmente nos pastos, apresentando altas cargas parasitárias na maioria dos meses do ano, sendo as principais espécies identificadas: Cooperia punctata e Haemonchus contortus. Os resultados indicam que os nematódeos da fazenda apresentam resistência anti-helmíntica, principalmente às lactonas macrocíclicas, e o desenvolvimento de imunidade foi primordial para reduzir a carga parasitária dos animais mestiços.

Background: in Colombia, the control of tick infestation in cattle is almost exclusively performed with chemical acaricides. It is important to determine the degree of resistance of Riphicephalus microplus field populations to ivermectins (IVM) as the first step to design strategies to increase the useful life of acaricides and decrease the reliance on chemical controls. Objective: to test the degree of resistance to IVM. Methods: three cattle farms in Antioquia (Colombia) where IVM had previously failed to control infestations of R. microplus ticks were studied. Ticks were collected several months apart in 2013, and the larval immersion test (LIT) was performed on the progeny of the adult females. Concentration-mortality data were subjected to probit analysis. Results: the three populations showed lethal concentrations (LC) 50 and 99 of ≥ 30 ppm and ≥ 400 ppm, respectively. There was no difference observed in the LC at different times of collection for each population studied. Such high values for LC, together with very low regression slopes (≤ 2), indicated a very heterogeneous response to increasing concentrations of IVM, which is common for resistant populations. At two farms, subcutaneous injection with a long-acting formulation of IVM at a dosage of 630 μg/Kg was ineffective at eliminating existing infestations and protecting against reinfestations, confirming farmer suspicions of lost efficacy. Conclusion: epidemiological studies are necessary to assess the current status of resistance to IVM in this region of Colombia, and it is likely that the intensive use of IVM will aggravate this situation in the future. [ABSTRACT FROM AUTHOR]

Avaliou-se a eficácia de lactonas macrocíclicas (ivermectina e moxidectina) sobre a eventual ocorrência de efeitos colaterais e acompanharam-se, após a alta parasitológica, por 12 meses, os cães tratados, visando detectar a recidiva do quadro dermatopático. Dos 63 animais, 59% eram fêmeas, 76% apresentavam precisa definição racial e 67% tinham pelame curto. A ivermectina (0,6mg/kg/dia) foi administrada por via oral a 31 cães, e a moxidectina (0,5mg/kg/cada 72 horas), pela mesma via, a 32 animais. Os tempos médios para a obtenção da primeira negativação do exame parasitológico do raspado cutâneo e para a consecução da alta foram, respectivamente, de 90 e 130 dias para a ivermectina e de 108 e 147 dias para a moxidectina. A ivermectina acarretou menos (16,1%) efeitos colaterais em relação à moxidectina (37,5%) (P=0,03). As recidivas foram, respectivamente, 10,3% e 13% para ivermectina e moxidectina. Não houve diferença entre os dois protocolos de terapia quanto aos percentuais de recidiva (P=0,67) e eficácia (P=0,61). Ambas as lactonas macrocíclicas mostraram-se eficazes: ivermectina 89,7% e moxidectina 87%.The efficacy of ivermectin and moxidectin for treatment of generalized canine demodicosis, was evaluated to detect the eventual occurrence of side effects caused by the use of these drugs, and to follow the treated dogs for 12 months after obtaining parasitologic cure. Of 63 dogs, 59% were females, 76% were defined as purebred and 67% had short hair. Ivermectin (0.6mg/kg/daily) was orally administered to 31 dogs and moxidectin (0.5mg/kg/every 72 hours) to 32 dogs. The average number of days to obtain the first negative skin scraping results and the parasitologic cure were, respectively, 90 and 130 days for ivermectin, and 108 and 147 days for moxidectin. Ivermectin caused fewer side effects (16.1%) than moxidectin (37.5%) (P0.67) and efficacy (P>0.61). Both drugs were effective and safe to treat generalized canine demodicosis: ivermectin 89.7% and moxidectin 87.0%.

The broad spectrum of endectocides and the easy use mode of their pour-on formulations are factors that have stimulated a higher frequency of use these drugs in cattle. In this study was evaluated the efficacy of ivermectin pour-on using the dose of 500mcgkg-1, against nematodes in naturally infected cattle from different herds. Twelve calves were brought from each of the four farms selected. All the 48 calves used showed mean of eggs per gram of feces (EPG) greater than 500 considering three consecutive counts. Subsequently, animals from each herd were divided into two groups of six animals each, one treated pour-on with ivermectin 500mcgkg-1 and other kept as untreated control. Calves were euthanized 14 days after treatment for counting the endoparasites. Ivermectin showed null effect against H. placei in all the herds evaluated. The drug was also ineffective against C. punctata in the herds from Jaboticabal,SP and Formiga, MG, and reached efficacy of 75.8% and 58.4% in herds from São José do Rio Pardo, SP and São Sebastião do Paraíso,MG, respectively. Efficacies of 94.2% (Jaboticabal), 0.0% (São José do Rio Pardo), 94.2% (Formiga) and 39.2% (São Sebastião do Paraíso) were detectedagainstO. radiatum. Based on these results obtained on the present study, the four populations of Haemonchus placei and Cooperia punctata evaluated were resistant to ivermectin pour-on using a dose of 500mcgkg-1. Ivermectin-resistant strains of Oesophagostomum radiatum were found in two of the four herds evaluated. [ABSTRACT FROM AUTHOR]

The article presents research which compared the effects of ivermectin (IVM) and moxidectin (MOX) on the strain of a known resistance status through the in vitro larval migration on agar test (LMAT). Researchers obtained third stage larvae of the selected isolated from faecal cultures of incubated infected sheep. They used a four-parameter logistic model to get the dose-response sigmoidal curves in the samples. They concluded that LMAT is an effective tool for tracking IVM and MOX resistance status and could be used for official routine drug monitoring initiatives.

Background: in Colombia, the control of tick infestation in cattle is almost exclusively performed with chemical acaricides. It is important to determine the degree of resistance of Riphicephalus microplus field populations to ivermectins (IVM) as the first step to design strategies to increase the useful life of acaricides and decrease the reliance on chemical controls. Objective: to test the degree of resistance to IVM. Methods: three cattle farms in Antioquia (Colombia) where IVM had previously failed to control infestations of R. microplus ticks were studied. Ticks were collected several months apart in 2013, and the larval immersion test (LIT) was performed on the progeny of the adult females. Concentration-mortality data were subjected to probit analysis. Results: the three populations showed lethal concentrations (LC) 50 and 99 of ≥ 30 ppm and ≥ 400 ppm, respectively. There was no difference observed in the LC at different times of collection for each population studied. Such high values for LC, together with very low regression slopes (≤ 2), indicated a very heterogeneous response to increasing concentrations of IVM, which is common for resistant populations. At two farms, subcutaneous injection with a long-acting formulation of IVM at a dosage of 630 μg/Kg was ineffective at eliminating existing infestations and protecting against reinfestations, confirming farmer suspicions of lost efficacy. Conclusion: epidemiological studies are necessary to assess the current status of resistance to IVM in this region of Colombia, and it is likely that the intensive use of IVM will aggravate this situation in the future.