RESUMEN
Cyathostomins are the largest group of parasites in horses that can be controlled by ivermectin (IVM). This study aimed to run a four-dose titration trial of IVM in 28 naturally infected Thoroughbred yearlings. The local Strongyle population had been recorded to be resistant to IVM (200 µg/kg). The parasite fecal egg count (FEC) was performed to investigate the egg reappearance period (ERP) of two and five weeks (w2pt and w5pt) after IVM treatment. FEC was > 1000 on day zero for all groups. Although 100% FEC reduction was reported at w2pt for all concentrations, the FEC at w5pt revealed < 83% efficacy. This study reports the reduction of ERP using the label dose as well as 300, and 400 µg/kg (double dose) of IVM. The protocol allowed IVM to significantly suppress FEC w2pt although not eliminating adult worms, failing to guarantee an extension of its protection period over 8 weeks. Moreover, the FEC at w5pt possibly means the infection was not cleared, and worms reestablished egg laying. We raised the possibility of withdrawing IVM of control programs when the drug has less than 80% FEC reduction at w5pt.
Asunto(s)
Ivermectina , Recuento de Huevos de Parásitos , Animales , Ivermectina/uso terapéutico , Ivermectina/administración & dosificación , Caballos/parasitología , Brasil , Enfermedades de los Caballos/parasitología , Enfermedades de los Caballos/tratamiento farmacológico , Enfermedades de los Caballos/diagnóstico , Femenino , Antiparasitarios/uso terapéutico , Antiparasitarios/administración & dosificación , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitología , Infecciones Equinas por Strongyloidea/diagnóstico , Heces/parasitologíaRESUMEN
In Argentina, as in the rest of the world, cyathostomins are the most common nematodes parasitizing horses. Control is based almost exclusively on the administration of benzimidazoles, pyrimidines, and macrocyclic lactones. However, intensive use of these drugs is resulting in the development of anthelmintic resistance (AR). For example, AR to benzimidazoles is currently distributed throughout Argentina, while incipient AR to pyrimidines (pyrantel embonate) is appearing in areas where this drug is used. Macrocyclic lactones and especially ivermectin, are by far the most used drugs by the vast majority of equine premises in the country. Although ivermectin has been used since 1982, its efficacy against equine strongylid parasites has remained very high until the present. In this study we report for the first time, the presence of a cyathostomin population with resistance to ivermectin in adult horses belonging to an equine premise located in central Argentina. Fecal egg count reduction tests (FECRT) were performed following the most recent guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP) for the diagnosis of anthelmintic resistance (research protocol) and resistance was considered when the Upper 90% Credible Interval fell below the expected efficacy threshold of 99.9%. Calculations were carried out using two different online calculation interfaces suggested by WAAVP. For the 14-day post-treatment interval, ivermectin efficacy was 79.5% (90% Credible Interval: 68.1-88.8) and 79.3% (74.2-83.6.3%) with the two methods, respectively. At 19 days post treatment, fecal egg count reductions were 68.6% (50.5-83.1) and 68.4% (61.9-74.1), respectively. At both intervals, this cyathostomin population fullfilled the criteria for AR. These findings suggest dispersion of ivermectin resistant cyathostomins in Argentina. Given the widespread use of macrocyclic lactones, it is important that veterinarians and the equine industry promote a more selective and evidence-based use of these drugs and establish routine monitoring to determine anthelmintic field efficacy to detect treatment failures as early as possible and avoid potential health problems as well as further spread of resistant genes.
Asunto(s)
Resistencia a Medicamentos , Ivermectina , Recuento de Huevos de Parásitos , Animales , Caballos , Ivermectina/farmacología , Ivermectina/uso terapéutico , Argentina , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitología , Antihelmínticos/farmacología , Heces/parasitología , Enfermedades de los Caballos/tratamiento farmacológico , Enfermedades de los Caballos/parasitología , Strongyloidea/efectos de los fármacosRESUMEN
Background: Strongylus vulgaris is one of the most pathogenic nematodes affecting equids. Larval migration through the cranial mesenteric artery (CMA) with attendant arteritis and thromboembolism can result in fatal non-strangulating intestinal infarction. Once considered a historical disease, recent studies have described the reemergence of this pathogen in several European countries; however, little is known of the current prevalence of S. vulgaris in the Canadian horse population. Objective: To determine the prevalence of active S. vulgaris cranial mesenteric arteritis in horses submitted for postmortem examination to the Diagnostic Services Unit (DSU) at the University of Calgary Faculty of Veterinary Medicine. Animals and procedure: We conducted a retrospective review of all equine postmortem cases submitted to the DSU between July 1, 2010 and June 30, 2022. Over 12 y, 510 horses > 2 mo of age from Alberta were submitted to the DSU for necropsy. Active cases were defined as those with endarteritis and thrombosis in the CMA or its branches. Those cases with only intimal scarring of the CMA were classified as historical. Results: The prevalence of all CMA lesions (both historical and active) over the study period was 17.3% (88/510). Active S. vulgaris cranial mesenteric arteritis was documented in 6.1% (31/510) of equine postmortems and the sequelae of verminous arteritis were the cause of euthanasia or death in 1.5% (8/510) of the cases submitted. Conclusion and clinical relevance: Even after historically intense efforts to eradicate this parasite, the continued effects of S. vulgaris are demonstrated by the results of this study. Strongylus vulgaris should not be regarded as a parasite of the past and verminous arteritis remains an important differential diagnosis for horses in western Canada presenting with mild colic or dull demeanor and anorexia of duration > 24 h. Furthermore, S. vulgaris should be taken into careful consideration when implementing antiparasitic control strategies. Practitioners should remain current on prevention, diagnosis, and treatment of this potentially reemerging and fatal equine disease.
Étude rétrospective de la prévalence lors d'autopsies équines de l'artérite mésentérique crâniale causée par Strongylus vulgaris en Alberta (2010 à 2022). Contexte: Strongylus vulgaris est l'un des nématodes les plus pathogènes affectant les équidés. La migration des larves à travers l'artère mésentérique crâniale (CMA), accompagnée d'artérite et de thromboembolie, peut entraîner un infarctus intestinal non étranglant mortel. Autrefois considérée comme une maladie historique, des études récentes ont décrit la réémergence de cet agent pathogène dans plusieurs pays européens; cependant, on sait peu de choses sur la prévalence actuelle de S. vulgaris dans la population équine canadienne. Objectif: Déterminer la prévalence de l'artérite mésentérique crâniale active à S. vulgaris chez les chevaux soumis pour examen post mortem au Diagnostic Service Unit (DSU), College of Veterinary Medicine, University of Calgary. Animaux et procédure: Nous avons effectué un examen rétrospectif de tous les cas post-mortem d'équidés soumis au DSU entre le 1er juillet 2010 et le 30 juin 2022. Sur 12 ans, 510 chevaux âgés de plus de 2 mois de l'Alberta ont été soumis au DSU pour autopsie. Les cas actifs ont été définis comme ceux présentant une endartérite et une thrombose dans la CMA ou ses branches. Les cas présentant uniquement des cicatrices à l'intima de la CMA ont été classés comme anciens. Résultats: La prévalence de toutes les lésions de CMA (anciennes et actives) au cours de la période d'étude était de 17,3 % (88/510). Une artérite mésentérique crâniale active à S. vulgaris a été documentée dans 6,1 % (31/510) des autopsies équines et les séquelles de l'artérite vermineuse ont été la cause de l'euthanasie ou du décès dans 1,5 % (8/510) des cas soumis. Conclusion et pertinence clinique: Malgré des efforts historiquement intenses pour éradiquer ce parasite, les effets continus de S. vulgaris sont démontrés par les résultats de cette étude. Strongylus vulgaris ne doit pas être considéré comme un parasite du passé et l'artérite vermineuse demeure un diagnostic différentiel important pour les chevaux de l'ouest du Canada présentant des coliques légères ou un comportement abattu et une anorexie de durée > 24 h. De plus, S. vulgaris doit être attentivement pris en compte lors de la mise en Åuvre de stratégies de contrôle antiparasitaire. Les praticiens doivent rester informés de la prévention, du diagnostic et du traitement de cette maladie équine potentiellement ré-émergente et mortelle.(Traduit par Dr Serge Messier).
Asunto(s)
Arteritis , Enfermedades de los Caballos , Strongylus , Animales , Caballos , Estudios Retrospectivos , Prevalencia , Femenino , Masculino , Alberta/epidemiología , Enfermedades de los Caballos/parasitología , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/patología , Arteritis/veterinaria , Arteritis/epidemiología , Arterias Mesentéricas/patología , Infecciones Equinas por Strongyloidea/epidemiología , Infecciones Equinas por Strongyloidea/parasitologíaRESUMEN
The aims of the present study were to identify strongyles in the feces of Thoroughbred horses based on larval morphology; to detect Strongylus vulgaris using molecular diagnosis and compare results to those of feces culture; and to determine the association between the presence of S. vulgaris with corresponding animal information (age range, gender, and anthelmintic use). Feces of horses kept in six Training Centers in Rio de Janeiro State, that showed the presence of ≥500 eggs per gram of feces (EPG) were subjected to strongyle identification. Of the 520 fecal samples collected, 35 had an EPG ≥ 500. After fecal culture for L3 larvae identification, DNA was extracted, subjected to PCR to amplify the ITS2 region DNA fragment of S. vulgaris, and sequenced. A total of 3500 larvae were analyzed. Most were classified as small strong (99.7%), with an emphasis on the type A subfamily of Cyathostominae. Forms of S. vulgaris only corresponded to 0.2%. In all, 25 samples showed amplified S. vulgaris DNA products and 11 showed nucleotide sequences with high sequence identity. Fecal culture and PCR results showed poor agreement (kappa = 0.105) for S. vulgaris diagnosis. Age, gender, anthelmintic use, and anthelmintic administration interval were not statistically significant. The present study showed the presence of S. vulgaris in the feces of horses kept in Rio de Janeiro Training Centers, mainly seen via PCR, which has emerged as the most effective tool for diagnosis. This study made it possible to identify strongyles that infect horses in the region, emphasizing upon the necessity for constant monitoring of the animals.
Asunto(s)
Heces , Larva , Infecciones Equinas por Strongyloidea , Strongylus , Animales , Caballos , Heces/parasitología , Brasil , Strongylus/aislamiento & purificación , Masculino , Infecciones Equinas por Strongyloidea/diagnóstico , Infecciones Equinas por Strongyloidea/parasitología , Femenino , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/parasitología , Recuento de Huevos de Parásitos/veterinaria , Reacción en Cadena de la Polimerasa/veterinaria , ADN de Helmintos/análisis , Antihelmínticos/uso terapéuticoRESUMEN
Pituitary pars intermedia dysfunction (PPID) is the most common endocrine disorder of older horses. Immune dysfunction in horses with PPID could increase susceptibility to infectious diseases, including strongyle infections; however, few data are available. The aim of this study was to determine if horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses, over a fourteen-week period in Victoria, Australia. Clinical signs and plasma adrenocorticotropic hormone (ACTH) concentrations were used to categorise horses into PPID (n=14) or control (n=31) groups. Faecal samples were collected for FEC determination prior to anthelmintic treatment, and fortnightly post-treatment for each horse. Generalised linear mixed modelling, using a gamma distribution, was used to compare differences between groups in the repeated measures study. The confounding variable of age was controlled for as a fixed effect. Following anthelmintic treatment, mean FEC was greater for the PPID group compared to the control group on day 56 (405 ± 756 eggs per gram [EPG] vs 40 ± 85 EPG, p=0.05) and day 70 (753 ±1598 EPG vs 82 ±141 EPG, p=0.04). There were no differences in mean FEC between groups on days 84 and 98. Cumulative FEC (day 14 to day 98) was significantly greater for the PPID horses than control horses (2118 ± 4016 EPG vs 798 ± 768 EPG, p<0.0001). Group egg reappearance period was shorter for PPID horses (day 56 post-anthelmintic treatment) compared to control horses (day 70) and 30% of the PPID horses reached a FEC threshold of >200 EPG on day 42, compared to 0% of control horses (p=0.02). These results suggest that the rate of a re-established patent infection between groups could be different due to a comprised immune response in PPID horses or differences in the host-parasite relationship regarding encysted stage larvae. However, despite differences between groups, some horses with PPID consistently had no detectable or low FEC (<200 EPG) during the study period. These findings highlight the importance of individual FEC monitoring to determine if anthelmintic treatment is required, in line with sustainable parasite management practices.
Asunto(s)
Antihelmínticos , Heces , Recuento de Huevos de Parásitos , Enfermedades de la Hipófisis , Adenohipófisis Porción Intermedia , Infecciones Equinas por Strongyloidea , Animales , Caballos , Recuento de Huevos de Parásitos/veterinaria , Heces/parasitología , Enfermedades de la Hipófisis/veterinaria , Enfermedades de la Hipófisis/parasitología , Antihelmínticos/uso terapéutico , Femenino , Infecciones Equinas por Strongyloidea/parasitología , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Masculino , Enfermedades de los Caballos/parasitología , Enfermedades de los Caballos/tratamiento farmacológico , Hormona Adrenocorticotrópica/sangre , VictoriaRESUMEN
A relatively new method to study the species richness and diversity of nematode parasites in grazing animals is to perform deep sequencing on composite samples containing a mixture of parasites. In this work, we compared species composition of strongyles in two groups of horses as a function of egg count and age, based on a DNA barcoding approach. Faecal egg counts and larval cultures were obtained from nearly 300 horses, i.e., domestic horses (n = 167) and trotters (n = 130) sampled nationwide. The second internal transcribed spacer region (ITS2) of strongyle nematodes in the larval cultures was first amplified using barcoded universal primers and then sequenced on the PacBio platform. Subsequently, bioinformatic sequence analysis was performed using SCATA to assign operational taxonomic units (OTU). Finally, species occurrence and composition were assessed using R. ITS2 sequences were found in the majority (89%) of larval samples. Sequencing yielded an average of 140 (26 to 503) reads per sample. The OTUs were assigned to 28 different taxa, of which all but three could be identified as species. The average relative abundance of the seven most abundant species (all Cyathostominae) accounted for 87% of the combined data set. The three species with the highest prevalence in both horse groups were Cyathostomum catinatum, Cylicocyclus nassatus and Cylicostephanus calicatus, and they were frequently found in different combinations with other species regardless of horse group. Interestingly, this result is largely consistent with a previous Swedish study based on morphological analysis of adult worms. In addition, two migratory strongylids (Strongylus vulgaris and S. edentatus) occurred in few domestic horses and trotters. Except for C. minutus and C. nassatus, which decreased with age, and C. catinatum and S. vulgaris, which increased, no specific trends were observed with respect to horse age. Taken together, these results are broadly consistent with data obtained before the introduction of selective targeted treatment in Sweden in 2007. All in all, our results suggest that this treatment strategy has not led to a significant change in strongyle nematode community structure in Swedish horses. The study also confirms that nemabiome analysis in combination with diversity index analysis is an objective method to study strongyle communities in horses.
Asunto(s)
Antihelmínticos , Enfermedades de los Caballos , Parasitosis Intestinales , Parásitos , Infecciones Equinas por Strongyloidea , Caballos , Animales , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/epidemiología , Infecciones Equinas por Strongyloidea/parasitología , Antihelmínticos/uso terapéutico , Strongyloidea/genética , Strongylus , Heces/parasitología , Larva , Parasitosis Intestinales/veterinaria , Enfermedades de los Caballos/tratamiento farmacológico , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/parasitología , Recuento de Huevos de Parásitos/veterinariaRESUMEN
BACKGROUND: Equine strongyles encompass more than 64 species of nematode worms that are responsible for growth retardation and the death of animals. The factors underpinning variation in the structure of the equine strongyle community remain unknown. METHODS: Using horse-based strongyle community data collected after horse deworming (48 horses in Poland, 197 horses in Ukraine), we regressed species richness and the Gini-Simpson index upon the horse's age, faecal egg count, sex and operation of origin. Using the Ukrainian observations, we applied a hierarchical diversity partitioning framework to estimate how communities were remodelled across operations, age groups and horses. Lastly, strongyle species counts collected after necropsy (46 horses in France, 150 in Australia) were considered for analysis of their co-occurrences across intestinal compartments using a joint species distribution modelling approach. RESULTS: First, inter-operation variation accounted for > 45% of the variance in species richness or the Gini-Simpson index (which relates to species dominance in communities). Species richness decreased with horse's age (P = 0.01) and showed a mild increase with parasite egg excretion (P < 0.1), but the Gini-Simpson index was neither associated with parasite egg excretion (P = 0.8) nor with horse age (P = 0.37). Second, within-host diversity represented half of the overall diversity across Ukrainian operations. While this is expected to erase species diversity across communities, community dissimilarity between horse age classes was the second most important contributor to overall diversity (25.8%). Third, analysis of species abundance data quantified at necropsy defined a network of positive co-occurrences between the four most prevalent strongyle genera. This pattern was common to necropsies performed in France and Australia. CONCLUSIONS: Taken together, these results show a pattern of ß-diversity maintenance across age classes combined with positive co-occurrences that might be grounded by priority effects between the major species.
Asunto(s)
Antihelmínticos , Líquidos Corporales , Enfermedades de los Caballos , Infecciones Equinas por Strongyloidea , Caballos , Animales , Antihelmínticos/uso terapéutico , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitología , Recuento de Huevos de Parásitos/veterinaria , Heces/parasitología , Enfermedades de los Caballos/parasitologíaRESUMEN
Macrocyclic lactones have been the most widely used drugs for equine parasite control during the past four decades. Unlike ivermectin, moxidectin exhibits efficacy against encysted cyathostomin larvae, and is reported to have persistent efficacy with substantially longer egg reappearance periods. However, shortened egg reappearance periods have been reported recently for both macrocyclic lactones, and these findings have raised several questions: (i) are egg reappearance period patterns different after ivermectin or moxidectin treatment? (ii) Are shortened egg reappearance periods associated with certain cyathostomin species or stages? (iii) How does moxidectin's larvicidal efficacy affect egg reappearance period? To address these questions, 36 horses at pasture, aged 2-5 years old, were randomly allocated to three treatment groups: 1, moxidectin; 2, ivermectin; and 3, untreated control. Strongylid fecal egg counts were measured on a weekly basis, and the egg reappearance period was 5 weeks for both compounds. Strongylid worm counts were determined for all horses: 18 were necropsied at 2 weeks post-treatment (PT), and the remaining 18 at 5 weeks PT. Worms were identified to species morphologically and by internal transcribed spacer-2 (ITS-2) rDNA metabarcoding. Moxidectin and ivermectin were 99.9% and 99.7% efficacious against adults at 2 weeks post treatment, whereas the respective efficacies against luminal L4s were 84.3% and 69.7%. At 5 weeks PT, adulticidal efficacy was 88.3% and 57.6% for moxidectin and ivermectin, respectively, while the efficacy against luminal L4s was 0% for both drugs. Moxidectin reduced early L3 counts by 18.1% and 8.0% at 2 or 5 weeks, while the efficacies against late L3s and mucosal L4s were 60.4% and 21.2% at the same intervals, respectively. The luminal L4s surviving ivermectin treatment were predominantly Cylicocyclus (Cyc.) insigne. The ITS-2 rDNA metabarcoding was in good agreement with morphologic species estimates but suggested differential activity between moxidectin and ivermectin for several species, most notably Cyc. insigne and Cylicocyclus nassatus. This study was a comprehensive investigation of current macrocyclic lactone efficacy patterns and provided important insight into potential mechanisms behind shortened egg reappearance periods.
Asunto(s)
Antihelmínticos , Enfermedades de los Caballos , Infecciones Equinas por Strongyloidea , Animales , Antihelmínticos/uso terapéutico , Antihelmínticos/farmacología , ADN Ribosómico , Resistencia a Medicamentos , Heces/parasitología , Enfermedades de los Caballos/tratamiento farmacológico , Enfermedades de los Caballos/parasitología , Caballos , Ivermectina/uso terapéutico , Macrólidos/uso terapéutico , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitología , Strongyloidea/genéticaRESUMEN
Essentially all grazing horses are infected with cyathostomin parasites. Adult cyathostomins reside in the large intestine of the horse and larval stages encyst within intestinal mucosa. Manual worm collection from aliquots of intestinal content is the current gold standard for retrieval and enumeration of luminal parasites, however, no research has been conducted to standardize specific parameters for processing and storage of samples. The aims of this study were (1) to evaluate the precision of current standard operating procedures for enumeration of luminal adult cyathostomin populations, (2) investigate the influence of chosen fixative, either 70 % ethanol or 10 % buffered formalin, as well as storage duration, immediately post necropsy vs. stored for eight weeks, on the magnitude and precision of worm counts, and (3) compare the luminal count magnitude between the three intestinal segments (cecum, ventral colon, dorsal colon). Ten miniature horses were enrolled in this study for euthanasia and necropsy over a four-week period. Luminal worm counts were conducted for 2 % aliquots of the cecum, ventral colon, and dorsal colon and samples were allocated to the two fixatives and the two storage durations. Precision was evaluated by coefficient of variation (CV) and was 13.04 % for total cyathostomin counts. Mean CV for large intestinal segments ranged from 15.31 % to 52.50 % irrespective of fixative used or storage duration. cecum worm counts were significantly lower compared to the ventral colon (p = 0.008) and dorsal colon (p = 0.01). Fixative and storage duration were not statistically associated with count precision or magnitude. This study demonstrated moderate to high precision estimates for luminal cyathostomin worm counts but did not identify any effects of fixative and storage duration within the framework of the study. This is the first study to determine cyathostomin worm count precision, and results will be useful for power analyses in the future.
Asunto(s)
Enfermedades de los Caballos , Infecciones Equinas por Strongyloidea , Animales , Ciego , Colon , Heces/parasitología , Fijadores , Enfermedades de los Caballos/parasitología , Caballos , Intestino Grueso/parasitología , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/parasitologíaRESUMEN
INTRODUCTION: Intestinal helminth management in horses has both clinical and epidemiologic relevance, in additional association with anthelmintic resistance. The Swiss Army employs military owned riding horses and privately owned pack horses, which are brought together for service periods up to 12 weeks. We compared husbandry conditions and intestinal helminth management of both groups via questionnaire and analysed faecal samples of 53 riding horses and 130 pack horses using combined sedimentation/flotation, the McMaster method and larval cultures. Riding horses only had cyathostomin infections (prevalence: 60,4 %), while pack horses harboured cyathostomins (71,5 %), Parascaris sp. (6,9 %) and Strongylus vulgaris (1,5 %). Regression models combining faecal sample results with questionnaire data unveiled correlations of husbandry practices with parasite frequencies identifying risk and protective factors. Pasture management, hygiene and deworming practices were highly variable for pack horses, while for riding horses there was an overall concept. This included a selective deworming strategy with faecal egg counts (FECs) of strongyles prior to deworming, applying a threshold of 200 eggs per gram of faeces (epg). Anthelmintic treatments based on FECs, weekly faeces removal on pastures (pastures), the use of macrocyclic lactones and deworming horses regularly were identified as protective factors regarding the 200 epg threshold for strongyle eggs. Accordingly, the mean epg for strongyle eggs between the groups (111 and 539 in riding and pack horses, respectively) was significantly different (p < 0,001). Overall, intestinal helminth management in pack -horses showed room for improvement regarding pasture hygiene, the used anthelmintics and the frequency of deworming, from which all Swiss Army horses would benefit, as they share pastures during their -service, therefore entailing the risk of parasite transmission.
INTRODUCTION: La gestion des helminthes intestinaux chez les chevaux présente une importance clinique et épidémiologique, en association avec la résistance aux anthelminthiques. L'armée suisse emploie des chevaux de selle militaires et des chevaux de bât privés qui sont réunis pour des périodes de service allant jusqu'à 12 semaines. Nous avons comparé la détention animale et la gestion des helminthes intestinaux des deux groupes par le biais d'un questionnaire et analysé les échantillons fécaux de 53 chevaux de selle et 130 chevaux de bât en utilisant la sédimentation/flottation combinée, la méthode McMaster et les cultures larvaires. Les chevaux de selle ne présentaient que des infections à cyathostomes (prévalence: 60,4 %), tandis que les chevaux de bât hébergeaient des cyathostomes (71,5 %), Parascaris sp. (6,9 %) et Strongylus vulgaris (1,5 %). Des modèles de régression combinant les résultats des échantillons fécaux et les données du questionnaire ont révélé des corrélations entre les pratiques de détention animale et la fréquence des parasites, identifiant les facteurs de risque et de protection. La gestion des pâturages, l'hygiène et les pratiques en matière de vermifugation étaient très variables pour les chevaux de bât, tandis que pour les chevaux de selle, il existait un concept unitaire. Ceci comprenait stratégie de vermifugation sélective avec comptage des Åufs fécaux (CEF) de strongles avant la vermifugation, en appliquant un seuil de 200 Åufs par gramme de fèces (opg). Les traitements anthelminthiques basés sur les CEF, l'enlèvement hebdomadaire des crottins sur le pâturage, l'utilisation de lactones macrocycliques et la vermifugation régulière des chevaux ont été identifiés comme des facteurs de protection concernant le seuil de 200 opg pour les Åufs de strongles. En conséquence, l'iog moyen pour les Åufs de strongles entre les groupes (111 et 539 chez les chevaux de selle et de bât, respectivement) était significativement différent (p < 0,001). Globalement, la gestion des helminthes intestinaux chez les chevaux de bât a montré qu'il est possible d'améliorer l'hygiène des pâturages, le choix des anthelminthiques et la fréquence des vermifuges, ce dont tous les chevaux de l'armée suisse bénéficieraient, car ils partagent les pâturages pendant leur service, ce qui entraîne un risque de transmission des parasites.
Asunto(s)
Antihelmínticos , Helmintos , Enfermedades de los Caballos , Infecciones Equinas por Strongyloidea , Animales , Antihelmínticos/uso terapéutico , Enfermedades de los Caballos/tratamiento farmacológico , Enfermedades de los Caballos/prevención & control , Caballos , Humanos , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitologíaRESUMEN
Strongylus vulgaris is the most pathogenic intestinal helminth parasite infecting horses. The migrating larvae in the mesenteric blood vessels can cause non-strangulating intestinal infarctions, which have a guarded prognosis for survival. Infections are typically diagnosed by coproculture, but a PCR test is available in some countries. While it is ideal to test horses individually, many veterinarians and clients wish to pool samples to reduce workload and cost of the diagnostic method. The purpose of this study was to determine if pooling of fecal samples would negatively impact diagnostic performance of the coproculture and the PCR for determination of S. vulgaris infection. Ten horses with strongylid eggs per gram (EPG) >500 and confirmed as either S. vulgaris positive or negative were selected as fecal donors. Eight pools with feces from five horses were created with 0%, 10 %, 20 %, 30 %, 40 %, 50 %, 80 %, and 100 % S. vulgaris positive feces. From each pool, 20 subsamples of 10 g each were collected and analyzed. Half of these samples were set up for coproculture and the other half for PCR. All pools containing 50 % or greater S. vulgaris positive feces were detected positive by both PCR and coproculture. In the pools with less than 50 % S. vulgaris positive feces, the PCR detected 33 positive samples compared to 24 with the coproculture. Three samples from the 0% pool were detected as low-level PCR positives, but this could be due to contamination. These results indicate that diagnosing S. vulgaris on pooled samples is reliable, when at least 50 % of the feces in a pool are from S. vulgaris positive animals. Since S. vulgaris remains relatively rare in managed horses, however, some diagnostic sensitivity is expected to be lost with a pooled sample screening approach. Nonetheless, pooled sample screening on farms could still be considered useful under some circumstances, and the PCR generally performed better at the lower proportions of S. vulgaris positive feces.
Asunto(s)
Enfermedades de los Caballos , Parasitosis Intestinales , Infecciones Equinas por Strongyloidea , Animales , Heces/parasitología , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/parasitología , Caballos , Parasitosis Intestinales/diagnóstico , Parasitosis Intestinales/parasitología , Parasitosis Intestinales/veterinaria , Óvulo , Reproducibilidad de los Resultados , Infecciones Equinas por Strongyloidea/diagnóstico , Infecciones Equinas por Strongyloidea/parasitología , Strongylus/aislamiento & purificaciónRESUMEN
AIMS: To generate different larval stages of Strongylus vulgaris and to study cytokine responses in cultures of eqPBMC exposed to defined larval stages of S. vulgaris and cyathostomins with the aim to understand the early immune reaction to these parasites. METHODS AND RESULTS: EqPBMC were exposed to S. vulgaris larvae (L3, exsheated L3 and L4) and cyathostomin L3 and analysed for cytokine gene expression. Procedures for decontamination, culturing and attenuation of larvae were established. Transcription of IL-4, IL-5 and IL-13 was induced by both S. vulgaris and cyathostomin L3. Moulting of S. vulgaris from L3 to L4 stage was accompanied by a shift to high expression of IL-5 and IL-9 (exsheated L3 and L4) and IFN-γ (L4 only). In parallel, the adjuvant G3 modified the cytokine profile induced by both parasites by reducing the expression of IL-4, IL-5 and IL-10 while concomitantly enhancing the expression of IFN-γ. CONCLUSION: The L4 stage of S. vulgaris generated a cytokine profile different from that induced by the earlier L3 stage of S. vulgaris and cyathostomins. This diversity depending on the life cycle stage will have implications for the choice of antigen and adjuvant in future vaccine design.
Asunto(s)
Citocinas/metabolismo , Enfermedades de los Caballos/inmunología , Larva/inmunología , Infecciones Equinas por Strongyloidea/parasitología , Strongylus/inmunología , Adyuvantes Inmunológicos/metabolismo , Animales , Enfermedades de los Caballos/parasitología , Caballos , Estadios del Ciclo de Vida , Strongylus/efectos de los fármacos , Strongylus/metabolismoRESUMEN
Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.
Asunto(s)
Antinematodos , Resistencia a Múltiples Medicamentos , Personal Militar , Infecciones Equinas por Strongyloidea , Estrongílidos , Animales , Antinematodos/farmacología , Antinematodos/uso terapéutico , Brasil , Heces/parasitología , Caballos , Larva/efectos de los fármacos , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Infecciones Equinas por Strongyloidea/parasitología , Estrongílidos/efectos de los fármacosRESUMEN
Fecal egg counts are the cornerstone of equine parasite control programs. Previous work led to the development of an automated, image-analysis-based parasite egg counting system. The system has been further developed to include an automated reagent dispenser unit and a custom camera (CC) unit that generates higher resolution images, as well as a particle shape analysis (PSA) algorithm and machine learning (ML) algorithm. The first aim of this study was to conduct a comprehensive comparison of method precision between the original smartphone (SP) unit with the PSA algorithm, CC/PSA, CC/ML, and the traditional McMaster (MM) and Wisconsin (MW) manual techniques. Additionally, a Bayesian analysis was performed to estimate and compare sensitivity and specificity of all five methods. Feces were collected from horses, screened with triplicate Mini-FLOTAC counts, and placed into five categories: negative (no eggs seen), > 0 - ≤ 200 eggs per gram (EPG), > 200 - ≤ 500 EPG, > 500 - ≤ 1000 EPG, and > 1000 EPG. Ten replicates per horse were analyzed for each technique. Technical variability for samples > 200 EPG was significantly higher for MM than CC/PSA and CC/ML (pâ¯<⯠0.0001). Biological variability for samples> 0 was numerically highest for CC/PSA, but with samples > 200 EPG, MM had a significantly lower CV than MW (pâ¯=⯠0.001), MW had a significantly lower CV than CC/PSA (pâ¯<⯠0.0001), CC/ML had a significantly lower CV than both MW and SP/PSA (pâ¯<⯠0.0001, pâ¯=⯠0.0003), and CC/PSA had a significantly lower CV than CC/SP (pâ¯=⯠0.0115). Sensitivity was> 98 % for all five methods with no significant differences. Specificity, however, was significantly the highest for CC/PSA, followed numerically by SP/PSA, MM, CC/ML, and finally MW. Overall, the automated counting system is a promising new development in equine parasitology. Continued refinement to the counting algorithms will help improve precision and specificity, while additional research in areas such as egg loss, analyst variability at the counting step, and accuracy will help create a complete picture of its impact as a new fecal egg count method.
Asunto(s)
Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/diagnóstico , Infecciones Equinas por Strongyloidea/parasitología , Animales , Heces/parasitología , Caballos , Recuento de Huevos de Parásitos/instrumentación , Recuento de Huevos de Parásitos/normas , Sensibilidad y Especificidad , Teléfono InteligenteRESUMEN
Horses are infected by a wide range of parasite species that form complex communities. Parasite control imposes significant constraints on parasite communities whose monitoring remains, however, difficult to track through time. Postmortem examination is a reliable method to quantify parasite communities. Here, we compiled 1,673 necropsy reports accumulated over 29 years, in the reference necropsy centre from Normandy (France). The burden of non-strongylid species was quantified and the presence of strongylid species was noted. Details of horse deworming history and the cause of death were registered. Building on these data, we investigated the temporal trend in non-strongylid epidemiology and we determined the contribution of parasites to the deaths of horses throughout the study period. Data analyses revealed the seasonal variations of non-strongylid parasite abundance and reduced worm burden in race horses. Beyond these observations, we found a shift in the species responsible for fatal parasitic infection from the year 2000 onward, whereby fatal cyathostominosis and Parascaris spp. infection have replaced cases of death caused by Strongylus vulgaris and tapeworms. A concomitant break in the temporal trend of parasite species prevalence was also found within a 10 year window (1998-2007) that has seen the rise of Parascaris spp. and the decline of both Gasterophilus spp. and tapeworms. A few cases of parasite persistence following deworming were identified, which all occurred after 2000. Altogether, these findings provide insights into major shifts in non-strongylid parasite prevalence and abundance over the last 29 years. They also underscore the critical importance of Parascaris spp. in young equids.
Asunto(s)
Helmintiasis Animal , Helmintos/parasitología , Caballos/parasitología , Animales , Infecciones por Ascaridida/epidemiología , Infecciones por Ascaridida/veterinaria , Ascaridoidea/parasitología , Autopsia , Heces/parasitología , Francia/epidemiología , Helmintiasis Animal/epidemiología , Helmintiasis Animal/parasitología , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/parasitología , Recuento de Huevos de Parásitos/veterinaria , Prevalencia , Estaciones del Año , Infecciones Equinas por Strongyloidea/epidemiología , Infecciones Equinas por Strongyloidea/parasitología , Strongylus/parasitologíaRESUMEN
Abstract Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.
Resumo O sistema semi-intensivo de criação de equinos favorece infecções por nematoides gastrointestinais. O tratamento dessas infecções é baseado no uso de anti-helmínticos. No entanto, o uso inadequado desses medicamentos levou à resistência parasitária aos princípios ativos disponíveis. O objetivo deste estudo foi avaliar a eficácia das principais classes de antiparasitários (ATP), utilizados no controle em animais adultos e jovens, incluindo: benzimidazois (fenbendazol), pirimidinas (pamoato de pirantel), lactonas macrocíclicas (ivermectina e moxidectina), bem como a combinação de ingredientes ativos (ivermectina + pamoato de pirantel). O estudo foi realizado em dois estabelecimentos militares, localizados no Rio Grande do Sul (RS), de janeiro a dezembro de 2018. Os intervalos entre os tratamentos foram realizados de 30 a 90 dias. As avaliações coproparasitológicas foram determinadas pela redução da contagem de ovos nas fezes. Foram identificadas larvas de ciatostomíneos nas coproculturas pré e pós tratamentos. Os resultados demonstraram a resistência parasitária múltipla dos ciatostomíneos ao fenbendazol, moxidectina em animais jovens, febendazole e pamoato de pirantel em animais adultos. Estabelecer o diagnóstico da resistência parasitária auxiliará na elaboração de um controle parasitário profilático, reduzindo o tratamento supressivo com ATP juntamente com alternativas de controle integrado. Dessa forma, o avanço da resistência parasitária poderá ser retardado.
Asunto(s)
Animales , Infecciones Equinas por Strongyloidea/parasitología , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Resistencia a Múltiples Medicamentos , Personal Militar , Antinematodos/uso terapéutico , Antinematodos/farmacología , Recuento de Huevos de Parásitos/veterinaria , Brasil , Estrongílidos/efectos de los fármacos , Heces/parasitología , Caballos , Larva/efectos de los fármacosRESUMEN
Selective anthelmintic therapy has been recommended as a sustainable strategy for cyathostomin control in horse populations for several decades. The traditional approach has been to determine strongyle fecal egg counts (FEC) for all horses, with treatment only recommended for those exceeding a predetermined threshold. The aims are to achieve a reduction of overall egg shedding, while leaving a proportion of the herd untreated, which lowers anthelmintic treatment intensity and reduces selection pressure for development of anthelmintic resistance. This study made use of the cyathostomin model to evaluate the influence of treatment strategies with between 1 and 8 yearly treatment occasions, where either 1) all horses were treated, 2) a predetermined proportion of the herd remained untreated, or 3) horses were treated if their FEC exceeded thresholds between 100 and 600 strongyle eggs per gram. Weather data representing four different climatic zones was used and three different herd age structures were compared; 1) all yearlings, 2) all mature horses 10-20 years old, and 3) a mixed age structure of 1-20 years of age. Results indicated a consistent effect of age structure, with anthelmintic resistance developing quickest in the yearling group and slowest among the mature horses. Development of anthelmintic resistance was affected by treatment intensity and selective therapy generally delayed resistance. Importantly, the results suggest that the effects of selective therapy on resistance development are likely to vary between climatic zones and herd age structures. Overall, a substantial delaying of resistance development requires that the average number of treatments administered annually across a herd of horses needs to be about two or less. However, results also indicate that an age-structured prioritisation of treatment to younger horses should still be effective. It appears that a 'one-size-fits-all' approach to the management of anthelmintic resistance in cyathostomins is unlikely to be optimal.
Asunto(s)
Antihelmínticos/administración & dosificación , Resistencia a Medicamentos , Infecciones Equinas por Strongyloidea/tratamiento farmacológico , Estrongílidos/efectos de los fármacos , Factores de Edad , Animales , Heces/parasitología , Femenino , Caballos , Masculino , Recuento de Huevos de Parásitos , Refugio de Fauna , Infecciones Equinas por Strongyloidea/parasitología , Estrongílidos/fisiologíaRESUMEN
Cyathostomins are pervasive equine parasites in horses across the world, and larval stages are known to cause the deadly disease larval cyathostominosis. The mucosal digestion technique is widely used for enumeration of encysted larval stages. Previous studies have investigated the spatial variation of encysted larvae, however current protocols lack a description of a standardized area from which to take the tissue sample. This study sought to evaluate spatial variation in encysted cyathostomin larval counts among the large intestinal organs and their subsections. Following humane euthanasia, ceca, ventral, and dorsal colons were harvested from 8 foals (aged 4-8 months) raised in an anthelmintic naïve parasitology research herd. Each organ was weighed and separated into 3 equal sections by length: the orad, intermediate, and aborad portions. From each of those sections, two 5% weight tissue samples were collected and digested to quantify the early third stage larvae (EL3) and late third stage larvae/fourth stage larvae (LL3/L4). A mixed model statistical analysis was carried out to evaluate for differences of larval counts among the different organs, sections, and the interaction term between the organs and sections. There were significant differences among organs (Pâ¯<â¯0.0001), with the ceca having higher counts than the ventral and dorsal colons. However, there were no significant differences among the three defined organ sections (Pâ¯=â¯0.1076). Coefficients of variation (CV) were all calculated to be greater than 1, suggesting a high level of variability among the samples; the least amount of variation can be found in the cecal data with a CV of 1.4024 compared with the ventral colon's 1.529845 and dorsal colon's 3.339135 within the respective organ. The following sections had the highest mean counts of encysted larvae: intermediate cecum, orad ventral colon, and aborad dorsal colon. Though only a portion of the results were significant, trends were observed and these should be investigated further in future studies and potentially employed in larvicidal efficacy evaluations.
Asunto(s)
Intestino Grueso/parasitología , Infecciones Equinas por Strongyloidea/parasitología , Animales , Caballos , Larva , Membrana Mucosa/parasitología , Carga de Parásitos , StrongyloideaRESUMEN
The detection and quantification of nematode eggs using fecal egg count techniques have an irreplaceable role in equine parasitic control. The reliability, particularly precision and accuracy, of individual techniques have been described only for strongylid infections. The aim of this study was to compare three fecal egg count techniques used for the detection of the two most common equine nematode infections: strongylid and ascarid. The Simple McMaster, Concentration McMaster and Mini-FLOTAC techniques were tested on spiked fecal samples with various levels of egg concentration (50, 100, 200, 500, 1000 and 3000 eggs per gram) and naturally infected mixed strongylid-ascarid samples with 30 replicates. The Simple McMaster, Concentration McMaster and Mini-FLOTAC techniques had precision coefficients of variation of 44.33, 35.64 and 18.25% for the strongylid infection and 62.95, 35.71 and 18.95% for the ascarid infection, and percent accuracies (mean count/number of eggs spiked) of 97.53, 88.39 and 74.18% for the strongylid infection and 65.53, 83.18 and 90.28% for the ascarid infection, respectively. Accuracy depended greatly on the type of nematode, but precision did not. The Mini-FLOTAC technique was more precise than the Simple and Concentration McMaster techniques regardless of nematode type. Simple McMaster was the most accurate technique for detecting strongylid eggs, and Mini-FLOTAC was the most accurate technique for detecting ascarid eggs. Our results indicated that none of the current techniques were universally and sufficiently reliable for the simultaneous quantification of both of these common equine nematodes.
Asunto(s)
Ascaridiasis/veterinaria , Heces/parasitología , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/parasitología , Recuento de Huevos de Parásitos/veterinaria , Infecciones Equinas por Strongyloidea/diagnóstico , Infecciones Equinas por Strongyloidea/parasitología , Animales , Ascaridiasis/diagnóstico , Ascaridiasis/parasitología , Caballos , Recuento de Huevos de Parásitos/normas , Reproducibilidad de los ResultadosRESUMEN
Previously described models for the free-living and parasitic phases of the cyathostomin life-cycle were combined into a single model for the complete life-cycle. The model simulates a single free-living population on pasture utilising parasite egg output from the horses and localised temperature and rainfall data to estimate infective larval density on herbage. Multiple horses of different ages are possible, each with an individualised anthelmintic treatment programme. Genotypes for anthelmintic resistance are included allowing for up to three resistance genes with 2 alleles each. Because little is known of the genetics of resistance to anthelmintics in cyathostomins, the first use of this model was to compare the effect of different assumptions regarding the inheritance of resistance on model outputs. Comparisons were made between single and two-gene inheritance, where the heterozygote survival was dominant, intermediate or recessive under treatment, and with or without a fitness disadvantage associated with the resistance mechanism. Resistance developed fastest when the heterozygotes survived anthelmintic treatment (i.e., were dominant) and slowest when they did not (i.e., were recessive). Resistance was slower to develop when inheritance was poly-genic compared to a single gene, and when there was a fitness cost associated with the resistance mechanism, although the latter variable was the least influential. Importantly, while these genetic factors sometimes had a large influence on the rate at which resistant genotypes built up in the model populations, their order of ranking was always the same, when different anthelmintic use strategies were compared. Therefore, the described model is a useful tool for evaluating different treatment and management strategies on their potential to select for resistance.