Toltrazuril + fenbendazole for cattle: Pharmacokinetics and efficacy against Eimeria spp. and gastrointestinal nematodes.

The present work evaluated the pharmacokinetics and efficacy of the association of 15cmg/kg toltrazuril +5cmg/kg fenbendazole against Eimeria spp. and gastrointestinal nematodes (GINs) in calves of different regions of Brazil (Center-West, Southeast, and South). A total of seven experiments were carried out, five of which determined formulation efficacy against Eimeria spp., considering the following aspects: therapeutic, preventive, metaphylactic, and residual efficacy. Therapeutic efficacy experiments for GINs were carried out by parasitological necropsy. The toltrazuril + fenbendazole association demonstrated ≥95% efficacy against Eimeria spp. for 21 days post-treatment (DPT). When used preventively and metaphylatically, the same association demonstrated ≥97% efficacy against E. zuernii, E. ellipsoidalis, E. cylindrica, E. bovis, E. wyomingensis and E. auburnensis. Toltrazuril + fenbendazole administered seven days before challenge was 100% effective against all these Eimeria species. Results of therapeutic, preventive, metaphylactic and residual efficacies can be related to the pharmacokinetic results, especially considering toltrazuril sulfone, which was detected in animal plasma for a longer period than the parent compound. Toltrazuril + fenbendazole achieved 100% anthelminthic efficacy against the GINs Haemonchus placei (L4), Cooperia pectinata and Oesophagostomum radiatum; 99.94% against adult H. placei; and 99.98% against C. puntacta. The association of toltrazuril + fenbendazole, associated with other measures, is an important and suitable tool for the control and treatment of Eimeria spp. and GINs in young cattle.

Long-term efficacy of toltrazuril in naïve calves prophylactically treated and experimentally infected with Eimeria spp.

Eimeria are ubiquitous parasites and eimeriosis treatment is based on coccidiostats or coccidicides used prophylactically, metaphylactically, or therapeutically. The long-term efficacy of toltrazuril (TZR, 15 mg/kg) against experimentally infected naïve calves was investigated. Seven groups (six treated and one control) of six animals each were formed. Animals of each group received a single TZR prophylactic oral treatment on days - 42, - 35, - 28, - 21, - 14, and - 7 before the challenge with infectious sporulated oocysts of Eimeria spp. (100,000 oocysts: 59.5% E. zuernii, 38.1% E. bovis, 1.2%, E. alabamensis, and 1.2% E. ellipsoidalis). The long-term efficacy was assessed based on Eimeria spp. oocyst excretion by fecal oocyst counts. Three calves from the control group presented diarrhea with blood, which was not observed in animals belonging to the treatment groups. The TZR achieved efficacy greater than 95.0% up to 14 and 7 days. This formulation showed efficacy above 95% for 7 to 14 days, between 82 and 84% for 21 to 28 days and between 50 and 64% for 35 to 42 days.

Morphometric analysis of aerobic Eimeria bovis sporogony using live cell 3D holotomographic microscopy imaging.

M onoxenous Eimeria species are widespread enteropathogenic apicomplexan protozoa with a high economic impact on livestock. In cattle, tenacious oocysts shed by E. bovis-infected animals are ubiquitously found and making infection of calves almost inevitable. To become infectious oocysts, exogenous oxygen-dependent E. bovis sporogony must occur leading to the formation of sporulated oocysts containing four sporocysts each harboring two sporozoites. Investigations on sporogony by live cell imaging techniques of ruminant Eimeria species are still absent in literature as commonly used fluorescent dyes do not penetrate resistant oocyst bi-layered wall. Sporogonial oocysts were daily analyzed by a 3D Cell Explorer Nanolive microscope to explore ongoing aerobic-dependent sporogony as close as possible to an in vivo situation. Subsequently, 3D holotomographic images of sporulating E. bovis oocysts were digitally stained based on refractive indices (RI) of oocyst bi-layered wall and sub-compartments of circumplasm using STEVE software (Nanolive), and the cellular morphometric parameters were obtained. Overall, three different E. bovis sporogony phases, each of them divided into two sub-phases, were documented: (i) sporoblast/sporont transformation into sporogonial stages, (ii) cytokinesis followed by nuclear division, and finally (iii) formation of four sporocysts with two fully developed sporozoites. Approximately 60% of sporulating E. bovis oocysts accomplished aerobic sporogony in a synchronized manner. E. bovis sporogony was delayed (i.e., 6 days) when compared to an in vivo situation where 2-3 days are required but under optimal environmental conditions. Live cell 3D holotomography analysis might facilitate the evaluation of either novel disinfectants- or anti-coccidial drug-derived effects on ruminant/avian Eimeria sporogony in vitro as discrimination of sporogony degrees based on compactness, and dry mass was here successfully achieved. Main changes were observed in the oocyst area, perimeter, compactness, extent, and granularity suggesting those parameters as an efficient tool for a fast evaluation of the sporulation degree.

Concomitant in vitro development of Eimeria zuernii- and Eimeria bovis-macromeronts in primary host endothelial cells.

Eimeria zuernii and E. bovis are host-specific apicomplexan parasites of cattle causing haemorrhagic typhlocolitis in young animals worldwide. During first merogony, both Eimeria species form giant macromeronts (>300 µm) in host endothelial cells containing >120,000 merozoites I in vivo. During the massive intracellular replication of macromeronts, large amounts of cholesterol and fatty acids are indispensable for enormous merozoite I-derived membrane production. From a metabolic perspective, host endothelial cells might be of advantage to the parasite, as transcription of several genes involved in both, cholesterol de novo biosynthesis and low density lipoprotein (LDL)-mediated uptake, are up-regulated in Eimeria macromeront-carrying host endothelial cells. In order to analyse further influence of E. zuernii/E. bovis infections on the metabolism of cholesterol, fatty acids, and glycolysis of the host endothelial cells, suitable in vitro cell culture systems are necessary. So far, in vitro cell culture systems based on primary bovine umbilical vein endothelial cells (BUVEC) are available for E. bovis-macromeront I formation, but have not been evaluated for E. zuernii. A novel E. zuernii (strain A), initially isolated from naturally infected calves in Antioquia, Colombia, was used for sporozoite isolation. Primary BUVEC monolayers were concomitantly infected with E. zuernii- and E. bovis-sporozoites, resulting in large sized macromeronts whose morphological/morphometric characteristics were compared. BUVEC carrying E. zuernii-macromeronts resulted in the release of viable and highly motile merozoites I. Overall, E. zuernii-merozoites I differed morphologically from those of E. bovis. The new E. zuernii (strain A) will allow detailed in vitro investigations not only on the modulation of cellular cholesterol processing (i. e. cholesterol-25-hydroxylase and sterol O-acyltransferase) but also on the surface expression of LDL receptors during macromeront formation.

Eimeria species in dairy and beef cattle of different ages in Goiás state, Brazil / Espécies de Eimeria em bovinos de leite e corte de diferentes idades no Estado de Goiás, Brasil

This study aimed to identify the frequency of occurrence of Eimeria species in Holstein (taurine dairy cattle) and Nelore (zebu beef cattle) on 12 farms in the state of Goiás, Brazil. A total of 2,601 animals were evaluated, and the cattle were divided into the following age-group categories: up to three months old, four to eight months old, nine to 16 months old and cows. Fecal samples were collected directly from the rectum of all animals. None of the cattle presented any clinical signs of eimeriosis during the survey. From the results obtained, it could be concluded that higher rates of infection by Eimeria spp. were observed in Holstein cattle between the 1st and 16 th months of age and in Nelore cattle between the 1st and 8th months of age. Twelve and nine Eimeria species were diagnosed in Holstein and Nelore cattle, respectively. However, Eimeria zuernii was more prevalent in animals up to three months old, while Eimeria bovis was more common in the remaining categories (cattle aged four months and over). Future studies on the epidemiology and/or seasonality of infection by Eimeria species in cattle, from birth onwards, are needed in order to better understand the dynamics of E. zuernii and E. bovis occurrences, especially in cattle under three months of age.(AU)

O presente trabalho teve como objetivo identificar a frequência das espécies de Eimeria spp. em bovinos holandeses (bovinos de leite) e Nelore (bovinos de corte) em 12 propriedades no Estado de Goiás. Foi avaliado um total de 2.601 animais, e em cada propriedade, os bovinos foram divididos nas seguintes categorias conforme a idade: até 3 meses, 4 a 8 meses, 9 a 16 meses e vacas. Amostras de fezes foram coletadas diretamente da ampola retal dos animais. Com base nos resultados obtidos pode-se concluir que em holandeses e Nelores, o maior número de bovinos infectados por Eimeria spp. foi observado do 1º ao 16º e do 1º ao 8º meses de idade, respectivamente. Não houve nenhum caso de eimeriose clínica durante a pesquisa. Doze e nove espécies de Eimeria foram diagnosticadas em holandeses e Nelores, respectivamente. As duas espécies mais frequentes foram Eimeria bovis e Eimeria zuernii, entretanto, E. zuernii foi mais prevalente em animais até os 3 meses de idade, enquanto que E. bovis foi a mais frequente nas demais categorias de bovinos, a partir dos 4 meses de idade. Futuros estudos relacionados à epidemiologia e/ou de sazonalidade da infecção por espécies Eimeria spp., em bovinos desde o seu nascimento, são necessários, a fim de melhor entender a dinâmica de ocorrência de E. zuernii e E. bovis principalmente em bezerros com até 3 meses de idade.(AU)

Eimeria species in dairy and beef cattle of different ages in Goiás state, Brazil / Espécies de Eimeria em bovinos de leite e corte de diferentes idades no Estado de Goiás, Brasil

Abstract This study aimed to identify the frequency of occurrence of Eimeria species in Holstein (taurine dairy cattle) and Nelore (zebu beef cattle) on 12 farms in the state of Goiás, Brazil. A total of 2,601 animals were evaluated, and the cattle were divided into the following age-group categories: up to three months old, four to eight months old, nine to 16 months old and cows. Fecal samples were collected directly from the rectum of all animals. None of the cattle presented any clinical signs of eimeriosis during the survey. From the results obtained, it could be concluded that higher rates of infection by Eimeria spp. were observed in Holstein cattle between the 1st and 16 th months of age and in Nelore cattle between the 1st and 8th months of age. Twelve and nine Eimeria species were diagnosed in Holstein and Nelore cattle, respectively. However, Eimeria zuernii was more prevalent in animals up to three months old, while Eimeria bovis was more common in the remaining categories (cattle aged four months and over). Future studies on the epidemiology and/or seasonality of infection by Eimeria species in cattle, from birth onwards, are needed in order to better understand the dynamics of E. zuernii and E. bovis occurrences, especially in cattle under three months of age.

Resumo O presente trabalho teve como objetivo identificar a frequência das espécies de Eimeria spp. em bovinos holandeses (bovinos de leite) e Nelore (bovinos de corte) em 12 propriedades no Estado de Goiás. Foi avaliado um total de 2.601 animais, e em cada propriedade, os bovinos foram divididos nas seguintes categorias conforme a idade: até 3 meses, 4 a 8 meses, 9 a 16 meses e vacas. Amostras de fezes foram coletadas diretamente da ampola retal dos animais. Com base nos resultados obtidos pode-se concluir que em holandeses e Nelores, o maior número de bovinos infectados por Eimeria spp. foi observado do 1º ao 16º e do 1º ao 8º meses de idade, respectivamente. Não houve nenhum caso de eimeriose clínica durante a pesquisa. Doze e nove espécies de Eimeria foram diagnosticadas em holandeses e Nelores, respectivamente. As duas espécies mais frequentes foram Eimeria bovis e Eimeria zuernii, entretanto, E. zuernii foi mais prevalente em animais até os 3 meses de idade, enquanto que E. bovis foi a mais frequente nas demais categorias de bovinos, a partir dos 4 meses de idade. Futuros estudos relacionados à epidemiologia e/ou de sazonalidade da infecção por espécies Eimeria spp., em bovinos desde o seu nascimento, são necessários, a fim de melhor entender a dinâmica de ocorrência de E. zuernii e E. bovis principalmente em bezerros com até 3 meses de idade.

Occurrences of eimeriosis in calves reared on small family farms - Scientific report / Ocorrência de eimeriose em bezerros criados em propriedades de agricultura familiar - Nota científica

Occurrences of eimeriosis were investigated among 110 Holstein-Friesian calves belonging to ten small family farms. Feces samples were collected from the rectum and were analyzed using qualitative and quantitative parasitological methods. In vitro sporulation was induced in feces samples positive for Eimeria sp. in order to subsequently identify the species under the microscope. All the farms were positive for species of the genus Eimeria with a prevalence of parasitized animals 48.2% for Eimeria. Eight species of the genus Eimeria were identified, among which E. bovis, E. auburnensis, and E. alabamensis were the most frequent, accounting for 23.6%, 11.8%, and 9.1%, respectively. Animals of up to six months of age that were managed collectively on pasture presented greater positivity for enteroparasites. The high prevalence of parasitic infection in young animals, especially due to coccidia of considerable pathogenicity, is an indicator of failure of sanitary management. Careful monitoring using specific drugs for controlling infections and reducing losses from animal rearing is needed.(AU)

A ocorrência de eimeriose foi pesquisada em 110 bezerros da raça holandesa pertencentes a dez propriedades de agricultura familiar. As amostras de fezes foram coletadas via retal e analisadas por métodos parasitológicos qualitativos e quantitativos. Amostras de fezes positivas para Eimeria sp. foram submetidas à esporulação in vitro para posterior  identificação microscópica da espécie. Todas as propriedades apresentaram positividade enteroparasitária por espécies do gênero Eimeria havendo uma prevalência de 48,2% dos animais parasitados. Foram identificadas oito espécies do gênero Eimeria, sendo E. Bovis, E. auburnensis e E. alabamensis as mais frequentes, com 23,6%, 11,8% e 9,1%, respectivamente. Animais com até seis meses de idade manejados de forma coletiva e a pasto apresentaram maior positividade enteroparasitária. A elevada prevalência de infecção parasitária em animais jovens, principalmente por coccidios de considerável patogenicidade, é indicador de falhas no manejo sanitário, sendo necessário criterioso monitoramento com uso de fármacos específicos para controlar infecções e reduzir perdas zootécnicas.(AU)

Occurrences of eimeriosis in calves reared on small family farms - Scientific report / Ocorrência de eimeriose em bezerros criados em propriedades de agricultura familiar - Nota científica

Occurrences of eimeriosis were investigated among 110 Holstein-Friesian calves belonging to ten small family farms. Feces samples were collected from the rectum and were analyzed using qualitative and quantitative parasitological methods. In vitro sporulation was induced in feces samples positive for Eimeria sp. in order to subsequently identify the species under the microscope. All the farms were positive for species of the genus Eimeria with a prevalence of parasitized animals 48.2% for Eimeria. Eight species of the genus Eimeria were identified, among which E. bovis, E. auburnensis, and E. alabamensis were the most frequent, accounting for 23.6%, 11.8%, and 9.1%, respectively. Animals of up to six months of age that were managed collectively on pasture presented greater positivity for enteroparasites. The high prevalence of parasitic infection in young animals, especially due to coccidia of considerable pathogenicity, is an indicator of failure of sanitary management. Careful monitoring using specific drugs for controlling infections and reducing losses from animal rearing is needed.

A ocorrência de eimeriose foi pesquisada em 110 bezerros da raça holandesa pertencentes a dez propriedades de agricultura familiar. As amostras de fezes foram coletadas via retal e analisadas por métodos parasitológicos qualitativos e quantitativos. Amostras de fezes positivas para Eimeria sp. foram submetidas à esporulação in vitro para posterior  identificação microscópica da espécie. Todas as propriedades apresentaram positividade enteroparasitária por espécies do gênero Eimeria havendo uma prevalência de 48,2% dos animais parasitados. Foram identificadas oito espécies do gênero Eimeria, sendo E. Bovis, E. auburnensis e E. alabamensis as mais frequentes, com 23,6%, 11,8% e 9,1%, respectivamente. Animais com até seis meses de idade manejados de forma coletiva e a pasto apresentaram maior positividade enteroparasitária. A elevada prevalência de infecção parasitária em animais jovens, principalmente por coccidios de considerável patogenicidade, é indicador de falhas no manejo sanitário, sendo necessário criterioso monitoramento com uso de fármacos específicos para controlar infecções e reduzir perdas zootécnicas.

OCORRÊNCIA DE EIMERIOSE EM BEZERROS CRIADOS EM PROPRIEDADES DE AGRICULTURA FAMILIAR - NOTA CIENTÍFICA

Abstract Occurrences of eimeriosis were investigated among 110 Holstein-Friesian calves belonging to ten small family farms. Feces samples were collected from the rectum and were analyzed using qualitative and quantitative parasitological methods. In vitro sporulation was induced in feces samples positive for Eimeria sp. in order to subsequently identify the species under the microscope. All the farms were positive for species of the genus Eimeria with a prevalence of parasitized animals 48.2% for Eimeria. Eight species of the genus Eimeria were identified, among which E. bovis, E. auburnensis, and E. alabamensis were the most frequent, accounting for 23.6%, 11.8%, and 9.1%, respectively. Animals of up to six months of age that were managed collectively on pasture presented greater positivity for enteroparasites. The high prevalence of parasitic infection in young animals, especially due to coccidia of considerable pathogenicity, is an indicator of failure of sanitary management. Careful monitoring using specific drugs for controlling infections and reducing losses from animal rearing is needed.

Resumo A ocorrência de eimeriose foi pesquisada em 110 bezerros da raça holandesa pertencentes a dez propriedades de agricultura familiar. As amostras de fezes foram coletadas via retal e analisadas por métodos parasitológicos qualitativos e quantitativos. Amostras de fezes positivas para Eimeria sp. foram submetidas à esporulação in vitro para posterior identificação microscópica da espécie. Todas as propriedades apresentaram positividade enteroparasitária por espécies do gênero Eimeria havendo uma prevalência de 48,2% dos animais parasitados. Foram identificadas oito espécies do gênero Eimeria, sendo E. Bovis, E. auburnensis e E. alabamensis as mais frequentes, com 23,6%, 11,8% e 9,1%, respectivamente. Animais com até seis meses de idade manejados de forma coletiva e a pasto apresentaram maior positividade enteroparasitária. A elevada prevalência de infecção parasitária em animais jovens, principalmente por coccidios de considerável patogenicidade, é indicador de falhas no manejo sanitário, sendo necessário criterioso monitoramento com uso de fármacos específicos para controlar infecções e reduzir perdas zootécnicas.