RESUMO
This study investigated the prevalence, production losses, spatial clustering, and predictive risk mapping in different climate zones in five states of Mexico. The bulk tank milk samples obtained between January and April 2015 were analyzed for antibodies against Ostertagia ostertagi using the Svanovir ELISA. A total of 1204 farm owners or managers answered the questionnaire. The overall herd prevalence and mean optical density ratio (ODR) of parasite were 61.96% and 0.55, respectively. Overall, the production loss was approximately 0.542 kg of milk per parasited cow per day (mean ODR = 0.92, 142 farms, 11.79%). The spatial disease cluster analysis using SatScan software indicated that two high-risk clusters were observed. In the multivariable analysis, three models were tested for potential association with the ELISA results supported by climatic, environmental, and management factors. The final logistic regression model based on both climatic/environmental and management variables included the factors rainfall, elevation, land surface temperature (LST) day, and parasite control program that were significantly associated with an increased risk of infection. Geostatistical kriging was applied to generate a risk map for the presence of parasite in dairy cattle herds in Mexico. The results indicate that climatic and meteorological factors had a higher potential impact on the spatial distribution of O. ostertagi than the management factors.
Assuntos
Anticorpos Anti-Helmínticos/imunologia , Doenças dos Bovinos/epidemiologia , Leite/imunologia , Ostertagia/imunologia , Ostertagíase/epidemiologia , Ostertagíase/veterinária , Animais , Anticorpos Anti-Helmínticos/análise , Bovinos , Doenças dos Bovinos/parasitologia , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Geografia , Modelos Logísticos , México/epidemiologia , Ostertagia/isolamento & purificação , Prevalência , Inquéritos e QuestionáriosRESUMO
The goals of the current study were to evaluate the potential pharmacokinetic (PK) interactions and the clinical efficacy occurring after the subcutaneous (s.c.) administration of ricobendazole (RBZ) and levamisole (LEV) given both separately and co-administered to calves naturally infected with susceptible gastrointestinal nematodes. The clinical efficacy was shown in two seasons, winter and spring, with predominance of different nematode populations. Groups of 15 calves were treated with RBZ alone, LEV alone and RBZ + LEV combination, and an untreated group was kept as a Control. RBZ and LEV plasma concentrations were quantified by HPLC. The clinical efficacy was determined by the faecal egg count reduction test. RBZ and LEV have similar plasma persistence, being detected in plasma over 24 hr post-treatment. No PK interactions were observed after the combined treatment, with similar PK parameters (p > .05) obtained for the single-drug and the combination-based strategy. In winter, the observed clinical efficacies were 96%, 99% and 100% for groups treated with RBZ, LEV and RBZ + LEV, respectively; however, in spring, the efficacies were 95%, 93% and 96% for the same groups. Remarkably, the combination was the only treatment that achieved 100% clinical efficacy against both Haemonchus spp and Ostertagia spp in winter; but the increased presence of Ostertagia spp. in spring (28% in untreated group) determined a tendency to reduced efficacies compared to winter time (only 10% of Ostertagia spp. in untreated group), even for the combined treatment. Overall, in a scenario where the nematode population is susceptible, the RBZ + LEV treatment may be a valid combination in cattle to delay the development of resistance, especially in winter when this combination achieved 100% of efficacy. Thus, selection of anthelmintic resistance will never occur. In fact, this is one of the greatest challenges for the whole cattle production system: to be one step ahead of anthelmintic resistance.
Assuntos
Albendazol/análogos & derivados , Antinematódeos/uso terapêutico , Levamisol/uso terapêutico , Albendazol/administração & dosagem , Albendazol/sangue , Albendazol/uso terapêutico , Animais , Antinematódeos/administração & dosagem , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Doenças dos Bovinos/parasitologia , Quimioterapia Combinada/veterinária , Hemoncose/tratamento farmacológico , Hemoncose/veterinária , Haemonchus/efeitos dos fármacos , Injeções Subcutâneas/veterinária , Levamisol/administração & dosagem , Levamisol/sangue , Masculino , Ostertagia/efeitos dos fármacos , Ostertagíase , Contagem de Ovos de Parasitas/veterinária , Estações do AnoRESUMO
Development of resistance to anthelmintic drugs has motivated the search for diagnostic methods to identify animals for targeted selective treatments. We compared three methods for the diagnosis of nematode infection in relation to milk production in a fully grazing dairy herd of 150 cows in the humid Pampa (Argentina). Animals had feces, blood and milk sampled during the first postpartum month for EPG, pepsinogen and anti-Ostertagia antibody determination, respectively. With the results obtained two groups of cows, divided in high and low parasite burden, were conformed for each method, and milk production was then compared between groups. When cows were separated by the EPG method (EPG=0 (N=106) vs. EPG>0 (N=44)) a difference of nearly 800 l of milk per cow per lactation was found (P<0.05). On the other hand, milk production between groups separated by Pepsinogen (mUtyr ≤ 1000 vs. mUtyr > 1000) or by anti-Ostertagia (ODR ≤ 0.5 vs. ODR > 0.5) results did not differ. Interestingly, proportion of cows in each group differed between methods (P<0.0001), and the anti-Ostertagia method yielded significantly more cows in the high index group compared to results using the EPG or Pepsinogen method. No correlations were found between parasite indexes determined by the different methods. High parasite burden estimation found may be ascribed to the production system, fully grazing all year round, and to the sampling time, at the beginning of lactation with cows in negative energy balance and depressed immunity. The fact that the cows were born and reared outside, on pasture with continuous nematode larvae exposure, may also account for the results obtained. In conclusion, EPG counting during the first postpartum month may be a useful tool for the diagnosis of production impairment induced by high nematode burden in adult grazing dairy cows. The anthelmintic treatment of only the EPG-positive recently calved cows would improve milk production, while reducing selective pressure on nematode population for the development of resistance.
Assuntos
Doenças dos Bovinos/diagnóstico , Gastroenteropatias/veterinária , Lactação , Nematoides/imunologia , Infecções por Nematoides/veterinária , Animais , Anticorpos Anti-Helmínticos/sangue , Argentina , Bovinos , Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/parasitologia , Indústria de Laticínios/métodos , Fezes/parasitologia , Feminino , Gastroenteropatias/diagnóstico , Gastroenteropatias/metabolismo , Gastroenteropatias/parasitologia , Nematoides/isolamento & purificação , Infecções por Nematoides/diagnóstico , Infecções por Nematoides/metabolismo , Ostertagia/imunologia , Ostertagia/isolamento & purificação , Ostertagíase/diagnóstico , Ostertagíase/parasitologia , Ostertagíase/veterinária , Contagem de Ovos de Parasitas/veterinária , Carga Parasitária/veterinária , Pepsinogênios/sangueRESUMO
The aim of this study was to determine the effect of environmental conditions and the time of exposure to the conditions required for Ostertagia ostertagi to become inhibited in development at the early fourth larval stage in the host. Two comparable experiments were conducted from September to January, experiment I in 1997-1998 and experiment II in 1999-2000. Twenty-thousand third-stage larvae (L3), freshly obtained from coprocultures, were spread in different parasite-free grass plots at the beginning of September, October and November in each experiment and exposed to environmental conditions throughout spring and early summer. Duplicate plots for each exposure period were grazed for 3 days by two dewormed tracer calves after 1, 2, 3, 4 weeks of exposure during the corresponding month, and the remaining plots were grazed for 3 days at monthly intervals until the end of the experimental period. For each month in both experiments, control animals were inoculated orally with 20,000 L3 newly recovered from coprocultures (week 0 animals; infection controls). The control and tracer calves were sacrificed and their parasite burdens analysed. The time required to obtain greater than 50% inhibited larvae (IeL4) in the tracer animals during September and October was 3 weeks, whereas during November around 60% of the parasites were inhibited after one week of exposure. During the period tested, greater than 50% inhibition was found in concurrence with a photoperiod ranging between 13 and 14 h. The highest proportion of IeL4 (75% average) in the animals was found concomitant with a 14 h 43 min photoperiod. A high correlation between the percentage of inhibition and day length was established (0.870 p < 0.001 and 0.815 p < 0.001 for experiment I and II, respectively). In both years, the capacity for developmental arrest was lost by the end of December, when the photoperiod begins to decrease, suggesting either a disappearance of the induction stimulus, or that an excess of the stimulus could block the mechanism of inhibition. The induction time was extended 2 weeks in all months tested when the coprocultures were maintained in the dark (experiment II), suggesting that accumulation of the light stimulus contributes to shortening of the induction time. The data presented here would suggest that photoperiod is a key environmental factor for the induction of hypobiosis.
Assuntos
Ostertagia/crescimento & desenvolvimento , Animais , Argentina , Bovinos , Doenças dos Bovinos/parasitologia , Meio Ambiente , Larva/crescimento & desenvolvimento , Masculino , Ostertagíase/parasitologia , Ostertagíase/veterinária , Fotoperíodo , Estações do Ano , Temperatura , ÁguaRESUMO
The appearance of variations in the protein profile of Ostertagia ostertagi (Stiles, 1892) infective larvae (L3), which were induced by hypobiosis triggering factors, was evaluated by means of SDS-PAGE and densitometric analysis. Area integration analyses of their protein profiles was carried out between 66 and 77 kDa. Important quantitative variations were identified in the protein levels of the induced larvae, where a 5.25 fold increase compared to the control was observed. Two 75.4 and 70 kDa protein bands were found which exceeded the control profile by 4.5 and 44 fold, respectively. This fact suggests that the changes brought about in the process of hypobiosis induction are restricted. This work demonstrates changes at a molecular level corresponding with biological changes induced by conditions causing O. ostertagi hypobiosis.
Assuntos
Doenças dos Bovinos/parasitologia , Proteínas de Helminto/metabolismo , Ostertagia/crescimento & desenvolvimento , Ostertagíase/veterinária , Animais , Bovinos , Eletroforese em Gel de Poliacrilamida/métodos , Larva/crescimento & desenvolvimento , Larva/metabolismo , Ostertagia/metabolismo , Ostertagíase/parasitologiaRESUMO
Two experiments were carried out to determine the causes producing the Ostertagia ostertagi hypobiosis phenomenon in cattle. In the first experiment, the effect of time on third-stage larvae in the environment was studied during a 2-year period. Three experimental paddocks contaminated with O. ostertagi eggs at different times of the year were used, and the levels of hypobiosis were recorded by using 'indicator' and 'tracer' calves. The results suggest that time as such is not a hypobiosis-inductive factor. The second experiment was conducted under laboratory conditions, where the effects of temperature and light on infective larvae were studied. Infective larvae were subjected to different conditions of temperature and light during 6 weeks, and then inoculated to parasite-naive calves, which were slaughtered after 4 weeks. Percentages of hypobiotic larvae in these calves varied from 3.5 to 94.8%, depending on the different storage conditions the larvae underwent before inoculation. Results suggest that increasing temperature and increasing time of light exposure simulating spring conditions would be the factors which act upon third-stage larvae inducing them to a later hypobiotic stage in the host.
Assuntos
Doenças dos Bovinos/parasitologia , Ostertagia/crescimento & desenvolvimento , Ostertagíase/veterinária , Abomaso/parasitologia , Animais , Argentina , Bovinos , Fezes/parasitologia , Temperatura Alta , Larva/crescimento & desenvolvimento , Luz , Masculino , Ostertagíase/parasitologia , Contagem de Ovos de Parasitas/veterinária , Poaceae/parasitologia , Estações do Ano , Fatores de TempoRESUMO
Two experiments were carried out to evaluate a larval development assay for the detection of anthelmintic resistance in O. circumcincta. In Experiment I, the dose responses to levamisole (LEV), thiabendazole (TBZ) and ivermectin (IVM) of 8 isolates of O. circumcincta were measured 34 days after infection (DAI). Four of these isolates were shown to be resistant to 1 or more anthelmintics. With 2 exceptions, all isolates considered to be resistant had higher LD50 values than the susceptible isolates for that anthelmintic. One exception was isolate RM8, which was considered to be resistant to all 3 anthelmintics based on faecal egg count reduction tests in goats, but the LD50 value for LEV did not differ from that for the susceptible isolates. The other exception was an isolate considered to be susceptible to TBZ which had a relatively high LD50 value. In an unrelated trial that was prompted by this finding, this isolate was confirmed to be benzimidazole-resistant. Isolate RM8 and an isolate susceptible to all 3 anthelmintics (SK2) were used in the second experiment, which was conducted to monitor changes in the LD50 values of LEV, TBZ and IVM over time following a single infection of 35,000 infective larvae in young sheep. Faecal samples were collected weekly from 24 to 115 DAI. With all 3 anthelmintics, the LD50 values increased with time to a peak around 50-60 DAI, and then declined to levels similar to those observed soon after patency. This trend was consistent for both isolates. The highest mean LD50 values for isolates SK2 for IVM and TBZ and RM8 for IVM and RM8, respectively, were 1.7 and 1.8 times, and 2.2 and 2.9 times higher than the initial mean LD50 values. There was a clear distinction in LD50 values between isolates at each sampling day for both IVM and TBZ. However, as a consequence of the changes in LD50 values with time, the peak LD50 values of IVM for isolate SK2 were higher than the minimum LD50 values of isolate RM8. As there was no apparent difference in LEV efficacy between these 2 isolates, the data were pooled. The highest mean LD50 value was 2.3 times higher than the initial LD50 value.
Assuntos
Anti-Helmínticos/farmacologia , Ostertagia/efeitos dos fármacos , Animais , Anti-Helmínticos/administração & dosagem , Relação Dose-Resposta a Droga , Resistência a Medicamentos , Estudos de Avaliação como Assunto , Feminino , Ivermectina/administração & dosagem , Ivermectina/farmacologia , Levamisol/administração & dosagem , Levamisol/farmacologia , Ostertagia/crescimento & desenvolvimento , Ostertagia/isolamento & purificação , Ostertagíase/tratamento farmacológico , Ostertagíase/parasitologia , Ostertagíase/veterinária , Contagem de Ovos de Parasitas , Parasitologia/métodos , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/parasitologia , Tiabendazol/administração & dosagem , Tiabendazol/farmacologia , Fatores de TempoRESUMO
Epidemiologic events in the life cycle of Ostertagia ostertagi are best known in the weaner-yearling phase of cattle development throughout the concentrated cattle-rising areas of the world. Animal and pasture management demands placed on this age class are greater than for suckling calves and adult stock in either beef or dairy breeds. This fact alone would likely account for a higher prevalence of clinical and subclinical disease in weaner-yearlings. Additionally, the developing immune response provides relatively early protection against intestinal genera such as Cooperia and Oesophagostomum, but is delayed against Ostertagia ostertagi and Trichostrongylus axei. Both Type I and Type II disease may occur within the weaner-yearling stage. Factors affecting population changes of Ostertagia ostertagi have been described as extrinsic, i.e. weather-climate and grazing management, and intrinsic or host factors, i.e. age, sex, immune status, heredity and reproductive state. Immune status, particularly in weaner-yearlings, may be of primary importance, as affected by host and extrinsic factors. With slow development of protective immunity against Ostertagia ostertagi in calves, the possible role of immunity in both induction of inhibition and larval maturation, the potential immunopathologic involvement in pathogenesis of Type II disease, hypersensitivity to larval intake in resistant adult cows, and the reported delay of a protective response following anthelmintic prophylaxis in younger cattle, the immune response may have profound influence on epidemiologic variation through age classes. Although continual epidemiological observations from birth to early adulthood in the same cattle have not been undertaken, some notable studies in the UK, the Netherlands, and Denmark have closely examined epidemiological events through first and second grazing seasons.
Assuntos
Doenças dos Bovinos/epidemiologia , Bovinos/crescimento & desenvolvimento , Bovinos/parasitologia , Ostertagíase/veterinária , Animais , Austrália/epidemiologia , Canadá/epidemiologia , Clima , Europa (Continente)/epidemiologia , Nova Zelândia/epidemiologia , Ostertagíase/epidemiologia , América do Sul/epidemiologia , Estados Unidos/epidemiologiaRESUMO
The nematode species Spiculopteragia spiculoptera, Spiculopteragia asymmetrica and Ostertagia leptospicularis were recovered from the abomasum of wild red deer, Cervus elaphus, in the forest area of the semi-arid Pampeana Region of La Pampa (Argentina) for the first time. Oesophagostomum venulosum and Dictyocaulus spp. were also found.
Assuntos
Cervos/parasitologia , Ostertagíase/veterinária , Tricostrongiloidíase/veterinária , Abomaso/parasitologia , Animais , Argentina/epidemiologia , Ostertagia/isolamento & purificação , Ostertagíase/epidemiologia , Ostertagíase/parasitologia , Trichostrongyloidea/isolamento & purificação , Tricostrongiloidíase/epidemiologia , Tricostrongiloidíase/parasitologiaRESUMO
This study was conducted to evaluate the effects of tactical treatments with ivermectin against trichostrongyles in first-season grazing heifer calves in the Danish marshland. A group of Black-Pied Friesian calves was turned out in early May on a permanent pasture naturally infected with trichostrongyle larvae. In late July, when high herbage infectivity started to appear, the pasture was divided into two plots of equal size, which from then and until housing in late October were each grazed by half of the original group of calves. One of these groups was given three anthelmintic treatments with ivermectin at 4-week intervals starting in late July. The other group served as non-treated controls. Ostertagia ostertagi and Cooperia oncophora were the predominant trichostrongyles. Nematodirus helvetianus was observed on few occasions. Although the animals were exposed to a high herbage infectivity from July onwards, the anthelmintic treatments conferred a significant reduction in trichostrongyle loads, as evidenced by an almost complete cessation of egg excretion and a significant lowering of pepsinogen and gastrin levels in the blood. This was reflected in higher weight gains.
Assuntos
Doenças dos Bovinos/prevenção & controle , Enteropatias Parasitárias/veterinária , Ivermectina/uso terapêutico , Tricostrongiloidíase/veterinária , Animais , Bovinos , Fezes/parasitologia , Feminino , Gastrinas/sangue , Enteropatias Parasitárias/prevenção & controle , Ostertagia/isolamento & purificação , Ostertagíase/prevenção & controle , Ostertagíase/veterinária , Contagem de Ovos de Parasitas/veterinária , Pepsinogênios/sangue , Estações do Ano , Soroalbumina Bovina/análise , Trichostrongyloidea/isolamento & purificação , Tricostrongiloidíase/prevenção & controle , Aumento de PesoRESUMO
Gastrointestinal parasitism has been recognized by practitioners as the most common disease in beef cattle, mainly in weaning calves and fattening steers. Among the different genera, Ostertagia ostertagi is the predominant parasite in the temperate climate, in which the major beef and dairy cattle area of South America is situated. Outbreaks of Type I ostertagiasis are usually seen after weaning time (autumn-winter) when larvae counts are high and food availability is low. The development of the disease is rapidly established and 15-30 kg are lost in 30-50 days. Epidemiological studies have demonstrated a fast evolution of parasite eggs to larvae (L3) in summer (1 week or less), evolution being 30-45 days during winter. Inhibition O. ostertagi occurs during spring (September-December) and development resumes in late summer and early autumn. The production effect is seen as a significant reduction in body weight gain and occasionally clinical Type II ostertagiasis appears. A similar epidemiological pattern of inhibition of Ostertagia sp. has been recorded in Uruguay and temperate areas in southern Brazil.