RESUMO
Biomarkers are specific molecular, histological, or physiological characteristics of normal or pathogenic biological processes and are promising in the diagnosis of gastrointestinal nematodes (GINs). Although some biomarkers have been validated for infection by Ostertagia sp. in cattle raised in temperate regions, there is a lack of information for tropical regions. The aim of this project was to assess potential biomarkers and validate the most promising. In the first study, 36 bovines (Nelore breed) naturally infected by GINs were distributed into two groups: infected (not treated with anthelmintic) and treated (treated with fenbendazole on days 0, 7, 14, 21, 28, 42, and 56). The variables of interest were live weight, fecal egg count, hemogram, serum biochemical markers, phosphorus, gastrin, and pepsinogen. In the second step, pepsinogen was assessed in cattle of the Nelore breed distributed among three groups: infected (not treated with anthelmintic), MOX (treated with moxidectin), and IVM + BZD (treated with ivermectin + albendazole). In the first study, no difference between groups was found for weight, albumin, hematocrit (corpuscular volume [CV]), erythrocytes, or hemoglobin. Negative correlations were found between pepsinogen and both CV and albumin, and albumin was negatively correlated with the percentage of Haemonchus sp. in the fecal culture. Among the biomarkers, only pepsinogen differentiated treated and infected (beginning with the 28th day of the study). In the second study, a reduction in pepsinogen was found after anthelmintic treatment. Therefore, pepsinogen is a promising biomarker of worms in cattle naturally infected by the genera Haemonchus and Cooperia in tropical areas.
Assuntos
Biomarcadores , Doenças dos Bovinos , Fezes , Infecções por Nematoides , Clima Tropical , Animais , Bovinos , Doenças dos Bovinos/parasitologia , Doenças dos Bovinos/tratamento farmacológico , Biomarcadores/sangue , Infecções por Nematoides/veterinária , Infecções por Nematoides/parasitologia , Infecções por Nematoides/tratamento farmacológico , Fezes/parasitologia , Contagem de Ovos de Parasitas , Anti-Helmínticos/uso terapêutico , Nematoides/isolamento & purificação , Nematoides/classificação , Nematoides/efeitos dos fármacos , Gastroenteropatias/parasitologia , Gastroenteropatias/veterinária , Enteropatias Parasitárias/veterinária , Enteropatias Parasitárias/parasitologia , Fenbendazol/uso terapêuticoRESUMO
BACKGROUND: The occurrence of higher winter temperatures in Brazilian areas with tropical and highland climates may result in a fifth peak of tick populations during winter in addition to the four generations previously described. Therefore, a strategic control protocol was developed with treatments in two seasons with the objective of controlling the generations of ticks that occur in spring/summer and those that occur in autumn/winter. METHODS: The study was conducted in Mato Grosso do Sul, Brazil, from the beginning of the rainy season, November 2020, to October 2021. In a randomized block design, 36 calves were distributed into three groups: (i) negative control; (ii) traditional strategic control in one season (SC1S), at the beginning of the rainy season; and (iii) strategic control in two seasons (SC2S), at the beginning and end of the rainy season. The SC1S strategic control group was treated on day 0, November 2020, and twice more with intervals of 42 days. The SC2S group received three more treatments beginning on day 182, May 2021, with intervals of 42 days. All treatments consisted of 5% fluralaner (Exzolt® 5%) delivered via a pour-on dose of 1 mL/20 kg body weight. Counts of semi-engorged female ticks were performed on day 3 and every 14 days thereafter, and the animals were weighed at the same time. RESULTS: Fluralaner showed a mean efficacy of more than 95% up to day 294. The two treated groups showed a decrease (P < 0.05) in the average number of ticks on day 3. In the SC2S group, the means were close or equal to zero throughout the study, while in the SC1S group, the means did not differ (P > 0.05) from those of the control group from day 231 onward. The final mean weight gain of each group was 76.40 kg, 98.63 kg, and 115.38 kg for the control, SC1S, and SC2S groups, respectively, differing (P < 0.05) from each other. CONCLUSIONS: Therefore, three applications of fluralaner, with one application every 42 days from the beginning of the rainy season in the middle spring, resulted in effective tick control for 224 days. When three additional treatments were given in autumn/winter with intervals of 42 days between applications, tick counts were reduced throughout the year. This strategic control approach may be indicated in years with climatic conditions that allow that population peaks are expected to occur in the autumn/winter period.
Assuntos
Rhipicephalus , Feminino , Bovinos , Animais , Isoxazóis/farmacologia , Brasil , ChuvaRESUMO
A possible synergistic effect of macrocyclic lactones' (MLs) combination has been previously described against resistant gastrointestinal nematodes of cattle. In addition to synergism, drug-drug interactions between MLs can also result in additive or antagonistic effect, considering the different MLs pharmacokinetics, pharmacodynamics, and interactions with molecular mechanisms of resistance. Therefore, the aim of the current work was evaluated the effect of different MLs combinations against Haemonchus contortus. Infecting larvae of two isolates (one susceptible and one resistant to ivermectin) were used in the larval migration inhibition test. After estimating the half maximal effective concentration of abamectin (ABA), eprinomectin, (EPR), ivermectin (IVM), and moxidectin (MOX) for both isolates, combinations were delineated by a simplex-centroid mixture experiment, and the mixture regression analysis was applied to the special cubic model. A synergistic effect was found for the EPR + MOX against the susceptible isolate as well as the EPR + MOX, IVM + MOX, and ABA + EPR + IVM against the resistant isolate. An antagonistic effect of ABA + IVM + MOX was found against the susceptible isolate. For the susceptible isolate, a higher inhibition was found with greater proportions of EPR and lower proportions of the other drugs compared to the reference mixture. For the resistant isolate, inhibition greater than that of the reference mixture was found with higher proportions of IVM as well as lower proportions of the other drugs. The synergistic and antagonistic effects were dependent on the following: (a) parasite drug resistance profile, (b) the composition of the combination, and (c) the proportions used, with EPR and IVM exerting a greater impact on these effects.
Assuntos
Anti-Helmínticos , Haemonchus , Animais , Bovinos , Ivermectina/farmacologia , Lactonas/farmacologia , Interações Medicamentosas , Resistência a Medicamentos , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêuticoRESUMO
Southern cattle tick resistance to pour-on and injectable acaricides has yet to be evaluated on a broader scope, and the paucity of information on the subject may hinder efforts to control this parasite. The objective of this study was to evaluate the resistance profile of ten populations of Rhipicephalus microplus to the acaricides fluazuron, fipronil and ivermectin in cattle herds in Mato Grosso do Sul, Brazil. The larval immersion test (LIT) was used to evaluate susceptibility to ivermectin and fipronil and the adult immersion test (AIT) was performed to evaluate fluazuron. Samples were randomly obtained in ten farms, and in general, we found resistance in five samples to fluazuron and in four samples to ivermectin and fipronil. Six samples showed incipient resistance to ivermectin and fipronil. Five of the ten evaluated samples showed resistance and/or incipient resistance to all the active ingredients, and the other five to two active ingredients. Among the samples classified as resistant, the average resistance ratio for ivermectin was 2.75 and 3.26 for fipronil. These results demonstrate the advanced status of resistance to the most modern chemical groups for the control of R. microplus in the state of Mato Grosso do Sul.
Assuntos
Acaricidas , Doenças dos Bovinos , Resistência a Medicamentos , Rhipicephalus , Infestações por Carrapato , Acaricidas/farmacologia , Animais , Brasil , Bovinos , Doenças dos Bovinos/parasitologia , Ivermectina/farmacologia , Compostos de Fenilureia/farmacologia , Pirazóis/farmacologia , Rhipicephalus/efeitos dos fármacos , Infestações por Carrapato/parasitologia , Infestações por Carrapato/veterináriaRESUMO
The objective of this study was to evaluate the therapeutic efficacy of 1 % injectable doramectin to control Dermatobia hominis in naturally infested beef cattle in a farm with history of clinical parasitism after avermectin use. The study was conducted in a commercial beef cattle farm in Brazil. Twenty crossbred cattle (Nellore x Angus) were selected based on the minimum number of 10 live larvae. Assessment of infestation was performed based on tactile-visual inspection of the entire body of the animals. The animals were allocated to two experimental groups of ten animals each: treated group - dosed with doramectin 200⯵g/kg live weight (LW), and control group - dosed with saline solution 1â¯mL/50â¯kg LW. Both treatments were administered subcutaneously in a single dose. After treatment, larval counts were performed at 1, 3, 7 and 14 days post-treatment (DPT). For the treatment to be considered efficient, it should reach an efficacy greater than or equal to 90 % by the 10th DPT and the average larval count in the treated animals should be statistically lower than the average larval count in the control group. The geometric means of larval counts at the beginning of the study were 27.2 and 26.3 for the control and treated groups, respectively. After 72â¯h of treatment, there was a significant reduction (pâ¯<â¯0.01) in the larvae counts of the treated group, extending to the 14th DPT, at which point maximum efficacy for doramectin (86.3 %) was obtained. After treatment, 90 % of the animals remained parasitized with live larvae on the 7th DPT and 70 % on the 14th DPT, while in the control group, all animals were infested on all dates. The administration of injectable doramectin was not effective in controlling D. hominis in naturally infested cattle.
Assuntos
Doenças dos Bovinos/parasitologia , Dípteros/efeitos dos fármacos , Inseticidas/farmacologia , Ivermectina/análogos & derivados , Miíase/veterinária , Animais , Bovinos , Resistência a Inseticidas , Ivermectina/farmacologia , Miíase/parasitologiaRESUMO
Southern cattle tick resistance to pour-on and injectable acaricides has yet to be evaluated on a broader scope, and the paucity of information on the subject may hinder efforts to control this parasite. The objective of this study was to evaluate the resistance profile of ten populations of Rhipicephalus microplus to the acaricides fluazuron, fipronil and ivermectin in cattle herds in Mato Grosso do Sul, Brazil. The larval immersion test (LIT) was used to evaluate susceptibility to ivermectin and fipronil and the adult immersion test (AIT) was performed to evaluate fluazuron. Samples were randomly obtained in ten farms, and in general, we found resistance in five samples to fluazuron and in four samples to ivermectin and fipronil. Six samples showed incipient resistance to ivermectin and fipronil. Five of the ten evaluated samples showed resistance and/or incipient resistance to all the active ingredients, and the other five to two active ingredients. Among the samples classified as resistant, the average resistance ratio for ivermectin was 2.75 and 3.26 for fipronil. These results demonstrate the advanced status of resistance to the most modern chemical groups for the control of R. microplus in the state of Mato Grosso do Sul.(AU)
A resistência do carrapato-do-boi a acaricidas com modo de aplicação "pour-on" e injetáveis é pouco avaliada em estudos mais abrangentes, e essa escassez de informação pode resultar falhas no seu controle. Este estudo teve como objetivo avaliar o perfil de resistência em dez populações de Rhipicephalus microplus aos acaricidas fluazuron, fipronil e ivermectina, em rebanhos bovinos em Mato Grosso do Sul, Brasil. A caracterização fenotípica da resistência foi realizada por meio do teste de imersão de adultos (AIT) para o fluazuron, e teste de imersão de larvas (LIT) para fipronil e ivermectina. As amostras foram obtidas aleatoriamente em dez fazendas, sendo diagnosticada resistência em cinco amostras ao fluazuron e em quatro amostras à ivermectina e fipronil. Seis amostras apresentaram resistência incipiente à ivermectina e fipronil. Cinco das dez amostras avaliadas apresentaram resistência e / ou resistência incipiente a todos os princípios ativos, e as outras cinco a dois princípios ativos. Entre as amostras classificadas como resistentes, a média do fator de resistência para ivermectina foi de 2,75 e de 3,26 para fipronil. Esses resultados demonstram o avançado estado de resistência aos mais modernos grupos químicos para o controle de R. microplus em Mato Grosso do Sul.(AU)
Assuntos
Rhipicephalus/imunologia , Rhipicephalus/parasitologia , Ivermectina/efeitos adversos , Ivermectina/análise , Acaricidas/imunologiaRESUMO
The aim of the present study was to test the in vitro acaricidal activity of saturated fatty acids (hexanoic, octanoic, decanoic, lauric, myristic, palmitic, octadecanoic, eicosanoic, docosanoic and tetracosanoic) against Rhipicephalus microplus and select a candidate compound for the subsequent determination of its clinical safety for mice and bovines as well as its in vivo efficacy (ethical clearance number 507/2013). None of the compounds exhibited in vitro larvicidal effectiveness, but acaricidal effectiveness was greater than 95 % in the adult immersion test at 40â¯mg/ml (hexanoic, octanoic, decanoic, lauric, myristic, palmitic and eicosanoic acids). After a second AIT evaluation of serial concentrations of the fatty acids, lauric and myristic acids were selected for the safety and in vivo efficacy assays. No adverse effect was found in the local lymph node assay in mice treated with lauric or myristic acid. Moreover, no clinical signs of systemic poisoning or dermatological, hematological or biochemical abnormalities were found in cattle after the topical application of 1 % lauric acid. In the dose determination test, the 1% solution of this compound exhibited 86% efficacy in cattle naturally infested by a field population of Rhipicephalus microplus susceptible to all chemical groups, except synthetic pyrethroids. The efficacy of 1 % lauric acid was 53.4 % in the dose confirmation test performed on another herd with a field R. microplus population resistant to all chemical groups of acaricides. In conclusion, fatty acids are potential bioactive compounds for the control of R. microplus. Topically applied lauric acid (C12) exhibits in vivo acaricide activity against adults, nymphs and larvae of R. (B) microplus and is safe for cattle.
Assuntos
Acaricidas , Doenças dos Bovinos/prevenção & controle , Ácidos Láuricos , Rhipicephalus , Infestações por Carrapato/veterinária , Acaricidas/efeitos adversos , Animais , Bovinos , Feminino , Larva/crescimento & desenvolvimento , Ácidos Láuricos/efeitos adversos , Ninfa/crescimento & desenvolvimento , Rhipicephalus/crescimento & desenvolvimento , Infestações por Carrapato/prevenção & controleRESUMO
Plant extracts are a potential source of new compounds for nematode control and may be an excellent alternative for the control gastrointestinal nematodes that are resistant to conventional anthelmintics. However, research involving natural products is a complex process. The main challenge is the identification of bioactive compounds. Online analytical techniques with universal detectors, such as high-performance liquid chromatography-mass spectrometry (HPLC-MS), together with metabolomics could enable the fast, accurate evaluation of a massive amount of data, constituting a viable option for the identification of active compounds in plant extracts. This study focused on the evaluation of the ovicidal activity of ethanol extracts from 17 plants collected from the Pantanal wetland in the state of Mato Grosso do Sul, Brazil, against eggs of Haemonchus placei using the egg hatchability test. The ethanol extracts were obtained using accelerated solvent extraction. The data on ovicidal activity, mass spectrometry and metabolomics were evaluated using HPLC-DAD-MS, partial least squares regression analysis (PLS-DA) and a correlation map (univariate correlation analyses) to detect compounds that have a positive correlation with biological activity. Among the ten metabolites with the best correlation coefficients, six were phenylpropanoids, two were triterpene saponins, one was a brevipolide, and one was a flavonoid. Combinations of metabolites with high ovicidal action were also identified, such as phenylpropanoids combined with the triterpene saponins and the flavonoid, flavonoids combined with iridoid and phenylpropanoids, and saponins combined with phenylpropanoid. The positive correlation between classes of compounds in plants belonging to different genera and biological activity (as previously identified in the literature) reinforces the robustness of the statistical data and demonstrates the efficacy of this method for the selection of bioactive compounds without the need for isolation and reevaluation. The proposed method also enables the determination of synergism among the classes, which would be impracticable using traditional methods. The present investigation demonstrates that the metabolomic technique was efficient at detecting secondary metabolites with ovicidal activity against H. placei. Thus, the use of metabolomics can be a tool to accelerate and simplify bioprospecting research with plant extracts in veterinary parasitology.
Assuntos
Antinematódeos/análise , Etanol/análise , Metabolômica/métodos , Plantas/química , Animais , Antinematódeos/farmacologia , Brasil , Cromatografia Líquida de Alta Pressão , Etanol/farmacologia , Flavonoides/análise , Flavonoides/farmacologia , Haemonchus/efeitos dos fármacos , Espectrometria de Massas , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/farmacologiaRESUMO
Canine visceral leishmaniasis frequently causes glomerulonephritis and tubulointerstitial nephritis, nephropathies for which diagnosis has been limited by the low sensitivity of traditional tests. The aim of this study was to evaluate serum cystatin C and urinary gamma-glutamyltransferase (uGGT) levels and the urinary GGT/urinary creatinine ratio (uGGT/uCR) and to measure the renal arterial resistive index (RARI) in dogs with leishmaniasis with varying degrees of renal injury based on the urine protein: creatinine ratio (UP/C) and serum creatinine (SCr) level. We tested 59 untreated adult dogs of both sexes and undefined breeds naturally infected with Leishmania infantum. The dogs were grouped into four groups based on UP/C and SCr level: group 1 (n = 15), dogs with SCr levels < 1.4 mg/dL and UP/C < 0.5; group 2 (n = 13), dogs with SCr levels < 1.4 mg/dL and UP/C of 0.5-1.0; group 3 (n = 16), dogs with SCr levels < 1.4 and UP/C > 1.0; and group 4 (n = 15), dogs with SCr levels > 1.4. A fifth group of healthy dogs (n = 10) was the control. uGGT concentrations and uGGT/uCR were higher in dogs with proteinuria and SCr < 1.4 mg/dL, whereas the serum cystatin C concentrations and RARI were higher only in dogs with SCr levels > 1.4. In conclusion, uGGT and uGGT/uCR may be useful tools for early detection and assessment of renal lesions associated with leishmaniasis; however, cystatin C is useful for monitoring the progression of kidney disease when measured sequentially.