Increasing importance of anthelmintic resistance in European livestock: creation and meta-analysis of an open database.

Helminth infections are ubiquitous in grazing ruminant production systems, and are responsible for significant costs and production losses. Anthelmintic Resistance (AR) in parasites is now widespread throughout Europe, although there are still gaps in our knowledge in some regions and countries. AR is a major threat to the sustainability of modern ruminant livestock production, resulting in reduced productivity, compromised animal health and welfare, and increased greenhouse gas emissions through increased parasitism and farm inputs. A better understanding of the extent of AR in Europe is needed to develop and advocate more sustainable parasite control approaches. A database of European published and unpublished AR research on gastrointestinal nematodes (GIN) and liver fluke (Fasciola hepatica) was collated by members of the European COST Action "COMBAR" (Combatting Anthelmintic Resistance in Ruminants), and combined with data from a previous systematic review of AR in GIN. A total of 197 publications on AR in GIN were available for analysis, representing 535 studies in 22 countries and spanning the period 1980-2020. Reports of AR were present throughout the European continent and some reports indicated high within-country prevalence. Heuristic sample size-weighted estimates of European AR prevalence over the whole study period, stratified by anthelmintic class, varied between 0 and 48%. Estimated regional (country) prevalence was highly heterogeneous, ranging between 0% and 100% depending on livestock sector and anthelmintic class, and generally increased with increasing research effort in a country. In the few countries with adequate longitudinal data, there was a tendency towards increasing AR over time for all anthelmintic classes in GIN: aggregated results in sheep and goats since 2010 reveal an average prevalence of resistance to benzimidazoles (BZ) of 86%, macrocyclic lactones except moxidectin (ML) 52%, levamisole (LEV) 48%, and moxidectin (MOX) 21%. All major GIN genera survived treatment in various studies. In cattle, prevalence of AR varied between anthelmintic classes from 0-100% (BZ and ML), 0-17% (LEV) and 0-73% (MOX), and both Cooperia and Ostertagia survived treatment. Suspected AR in F. hepatica was reported in 21 studies spanning 6 countries. For GIN and particularly F. hepatica, there was a bias towards preferential sampling of individual farms with suspected AR, and research effort was biased towards Western Europe and particularly the United Kingdom. Ongoing capture of future results in the live database, efforts to avoid bias in farm recruitment, more accurate tests for AR, and stronger appreciation of the importance of AR among the agricultural industry and policy makers, will support more sophisticated analyses of factors contributing to AR and effective strategies to slow its spread.

TITLE: Importance croissante de la résistance aux anthelminthiques chez les ruminants européens : création et méta-analyse d'une base de données ouverte. ABSTRACT: Les helminthes sont omniprésents dans les systèmes de production de ruminants au pâturage et sont responsables de coûts et de pertes de production importants. La résistance aux anthelminthiques (RA) des parasites est maintenant répandue dans toute l'Europe, bien qu'il existe encore des lacunes dans nos connaissances dans certaines régions et certains pays. La RA est une menace majeure pour la pérennité de la production moderne de ruminants, en diminuant la productivité, en compromettant la santé et le bien-être des animaux, et en augmentant les émissions de gaz à effet de serre au travers d'une augmentation du parasitisme et des intrants agricoles. Une meilleure compréhension de l'étendue de la RA en Europe est nécessaire pour développer et préconiser des approches de lutte antiparasitaire plus durables. Une base de données intégrant des informations publiées et non publiées en Europe concernant la RA des nématodes gastro-intestinaux (NGI) et de la douve du foie (Fasciola hepatica) a été compilée par les membres de l'action européenne COST « COMBAR ¼ (« Combattre la résistance aux anthelminthiques chez les ruminants ¼) et combinée avec les données d'une précédente étude systématique concernant la RA des NGI. Au total, 197 publications sur la RA des NGI étaient disponibles pour analyse, représentant 535 études dans 22 pays et couvrant la période 1980­2020. Des signalements de RA étaient présents sur tout le continent européen et certains rapports indiquaient une forte prévalence nationale. Les estimations heuristiques pondérées par la taille de l'échantillon de la prévalence de la RA en Europe sur toute la période d'étude, stratifiées par classe d'anthelminthiques, variaient de 0 à 48 %. La prévalence régionale (nationale) estimée était très hétérogène, variant entre 0 % et 100 % selon le secteur de l'élevage et la classe d'anthelminthique, et augmentait généralement avec les efforts de recherche dans le pays. Dans les quelques pays disposant de données longitudinales adéquates, il y avait une tendance à l'augmentation de la RA au fil du temps pour toutes les classes d'anthelminthiques des NGI : les résultats agrégés chez les ovins et caprins depuis 2010 révèlent une prévalence moyenne de résistance aux benzimidazoles (BZ) de 86 %, aux lactones macrocycliques sauf moxidectine (ML) de 52 %, au lévamisole (LEV) de 48 % et à la moxidectine (MOX) de 21 %. Tous les genres principaux de NGI ont survécu au traitement dans diverses études. Chez les bovins, la prévalence de la RA variait selon les classes d'anthelminthiques de 0 à 100 % (BZ et ML), 0 à 17 % (LEV) et 0 à 73 % (MOX), et Cooperia et Ostertagia ont survécu aux traitements. Une RA suspectée chez F. hepatica a été signalée dans 21 études portant sur 6 pays. Pour les NGI, et encore plus pour F. hepatica, il y avait un biais d'échantillonnage en faveur des exploitations individuelles suspectées de RA, et l'effort de recherche était biaisé vers l'Europe occidentale et en particulier le Royaume-Uni. La capture continue des résultats futurs dans la base de données, en direct, les efforts pour éviter les biais dans le recrutement des exploitations, des tests plus précis pour la RA et une meilleure appréciation de l'importance de la RA parmi l'industrie agricole et les décideurs politiques, soutiendront des analyses plus sophistiquées des facteurs contribuant à la RA, et des stratégies efficaces pour ralentir sa propagation.

A Qualitative Market Analysis Applied to Mini-FLOTAC and Fill-FLOTAC for Diagnosis of Helminth Infections in Ruminants.

Helminth infections, mainly by gastrointestinal nematodes (GIN), are one of the main concerns for animal health, welfare and productivity in grazing ruminant livestock worldwide. The use of a sensitive, precise, accurate, low-cost, and easy-to-perform copromicroscopic technique is of pivotal importance to perform reliable fecal egg count (FEC) and fecal egg count reduction test (FECRT), in order to determine the need of anthelmintic treatment, but also anthelmintic efficacy or resistance. This approach is fundamental to a correct and efficient control of GIN. Unfortunately, in worldwide ruminant farm practice, repeated anthelmintic treatments are carried out, without prior diagnosis of infection, contributing to the spread of Anthelmintic Resistance (AR). Tackling this phenomenon, improving mainly the GIN diagnosis and AR status in farm animals, is a priority of the European COST Action "COMBAR-COMBatting Anthelmintic Resistance in Ruminants" and of the STAR-IDAZ International Research Consortium on Animal Health. One of the specific objectives of the COMBAR Working Group 1 (WG1) is to conduct an European market analysis of new diagnostics and develop a business plan for commercial test introduction, leveraging technical know-how of participants. Since the Mini-FLOTAC in combination with the Fill-FLOTAC may be considered a good candidate for a standardized FEC and FECRT in the laboratory, as well as directly in the field, the aim of this study was to conduct SWOT (Strength-Weaknesses-Opportunities-Threats) and PESTEL (Political, Economic, Social, Technological, Environmental, and Legal) analyses of these tools in 20 European countries involved in the COMBAR WG1, in order to identify the opportunities, barriers, and challenges that might affect the Mini-FLOTAC and Fill-FLOTAC commercialization in Europe.

100 Questions in Livestock Helminthology Research.

An elicitation exercise was conducted to collect and identify pressing questions concerning the study of helminths in livestock, to help guide research priorities. Questions were invited from the research community in an inclusive way. Of 385 questions submitted, 100 were chosen by online vote, with priority given to open questions in important areas that are specific enough to permit investigation within a focused project or programme of research. The final list of questions was divided into ten themes. We present the questions and set them briefly in the context of the current state of knowledge. Although subjective, the results provide a snapshot of current concerns and perceived priorities in the field of livestock helminthology, and we hope that they will stimulate ongoing or new research efforts.

Veterinary parasitology teaching - Ten years of experience with the Vetsuisse curriculum.

Pursuant to the Joint Declaration by 29 European education ministers in June 1999 in the city of Bologna, Italy, the so-called 'Bologna Process' was officially introduced at the Vetsuisse Faculty (Universities of Zurich and Berne) in Switzerland in 2007. The long-term goal of restructuring the study programmes was to create a common European Higher Education Area (EHEA), with uniform and clearly defined standards for degrees ("diplomas"). Accordingly, the Vetsuisse curriculum was organised as a 3-year Bachelor and a 2-year Master study program. For the final Federal examination in veterinary medicine, both programs and a master thesis have to be completed. Parasitology, as a subject, is introduced with selected examples in the ecology course during the first academic year. The second and third years of the Bachelor program comprise non-organ-centred (NOC) and integrated organ-centred (OC) course modules, respectively. In the NOC modules, parasitology is taught in consecutive courses, focussing on topics including occurrence, biology, pathogenesis, clinical manifestations, diagnostics and the strategic principles of therapeutic and prophylactic interventions against major veterinary and zoonotic parasites. This syllabus is complemented with live demonstrations as well as practical laboratory exercises. Lecture notes, with defined learning objectives, are based on the textbook "Parasitology in Veterinary Medicine" which is available free of charge to students as an on-line edition in German. Furthermore, students review relevant parasitoses in the diagnostic context of OC case presentations. In another module, immunological aspects of parasitic diseases are elaborated on group sessions, supported through the use of specialist literature. The two-year Master program is divided into a core syllabus for all students, and elective subjects are chosen from six areas of specialisation (three each with clinical or non-clinical focus). Within the clinically focused specialisations, interactive teaching of control strategies against parasitoses of companion and farm animals is the focus. Students specialising in 'Pathobiology' experience a deep immersion in parasitology. Learning objectives are verified in different test formats. E-learning tools, including a learning management on-line platform, allow interactive student training in coproscopic diagnostic techniques and in arachno-entomology and provide case-oriented teaching. Since an aptitude test limits the number of first-year students in veterinary medicine in Switzerland (80 in Zürich, 70 in Berne), the conditions for students and teachers are similar each year. The fragmentation of teaching in veterinary parasitology, the reduction of the number of diagnostic exercises and clinically oriented day-1-skills pertaining to the control of parasitoses are critically commented upon.

Benzimidazole resistance survey for Haemonchus, Teladorsagia and Trichostrongylus in three European countries using pyrosequencing including the development of new assays for Trichostrongylus.

Resistance to benzimidazoles (BZs) in trichostrongyloid nematodes is a worldwide problem for livestock production, particularly regarding small ruminants. Sensitive and reliable methods are required to assess anthelmintic resistance status. Currently available methods for BZ resistance detection can be divided into three main groups, in vivo (e.g. faecal egg count reduction test), in vitro (e.g. egg hatch assay) and molecular tests. Three single nucleotide polymorphisms (SNPs) in the isotype-1 ß-tubulin gene of various nematode species correlate with BZ resistance. While PCR-based methods have been reported for the three most economically important nematodes of sheep, namely, Trichostrongylus, Haemonchus and Teladorsagia, pyrosequencing assays are so far only available for the latter two. Here, the design and evaluation of pyrosequencing assays for isotype-1 and isotype-2 ß-tubulin genes of Trichostrongylus colubriformis are described. PCR fragments carrying the susceptible and corresponding resistant genotype were combined in defined ratios to evaluate assay sensitivity and linearity. The correlation between the given and the measured allele frequencies of the respective SNPs (codons F167Y, E198A and F200Y) was very high. Pyrosequencing assays for Haemonchus, Teladorsagia and Trichostrongylus were subsequently used for a BZ resistance survey, carried out in the three European countries, namely Ireland, Italy and Switzerland. Larval cultures obtained from field survey samples in 2012 and 2013 were used for pyrosequencing. The test was applied when the target species represented at least 10% of the sample. Trichostrongylus and Teladorsagia were detected in all countries' samples whereas Haemonchus was not detected in samples from Ireland. SNPs in isotype-1 associated with resistance were detected for all three species, with frequencies at codon F200Y far exceeding those at codons F167Y and E198A. Elevated SNP frequencies in isotype-2 of Trichostrongylus were only rarely detected. Farms with BZ resistance-associated SNP frequencies above 10% were most often found in Switzerland followed by Ireland and Italy.

Vaccination of goats against Haemonchus contortus with the gut membrane proteins H11/H-gal-GP.

Forty goats, aged from 2 to 5 months were subjected to two different immunization protocols with a vaccine containing Haemonchus contortus gut membrane proteins H11/H-gal-GP to evaluate protection against H. contortus on pre-contaminated pastures. Goats were allocated to four groups of ten, three of them received their first vaccination before turnout. One group (V4) was then vaccinated at 4-week-intervals whereas another two groups (V6 and V6SEP) were vaccinated at 6-week-intervals. A control group (CTRL) remained unvaccinated. In May, after the second vaccination, all goats were turned out on pastures which had been previously contaminated with H. contortus eggs by seeder sheep for a period of six weeks. Goats of groups V4, V6 and CTRL were grazed together, whereas V6SEP was kept separately at an identical stocking rate. Clinical (PCV, FAMACHA, body weight), parasitological (faecal egg count, FEC) and serological (antibody titres) parameters were measured fortnightly. All goats were stabled in October, drenched with levamisole and two weeks later infected with 5000 L3 of H. contortus and slaughtered four weeks later for determination of abomasal worm burdens. Group mean FEC peaked 42-56days after turnout. Significantly lower FEC were observed in V6SEP vs CTRL between D 28 and 70 (p<0.01). Mean egg output of all groups decreased substantially and fluctuated at low levels until the end of the grazing period (D 154). Goats responded to vaccination with increasing antibody titres peaking after every booster. Mean worm burdens deriving from experimental infections were reduced by 89, 65 and 47% in groups V4, V6 and V6SEP, respectively, compared with the controls. The difference was significant for V4 (p<0.01). Antibody titres measured 14days before slaughter did not correlate statistically with the worm burdens. It was concluded that the vaccination protocol did not result in sufficient protection on pasture, as antibody titres were still low at the time the goats were exposed to larval contamination on pasture after turnout.

Effect of gastro-intestinal nematode infection on sheep performance: a systematic review and meta-analysis.

BACKGROUND: Gastrointestinal nematode (GIN) infections are common in domestic sheep and impact directly and indirectly on the health of infected animals as well as on the associated economic production. In this study, we aim at summarizing the current knowledge on the influence of GIN infections on sheep production by conducting a systematic review. A subsequent meta-analysis of relevant studies was performed to provide an estimate of the effect of GIN infections on weight gain, wool production and milk yield. METHODS: A literature search was performed on the CAB, Pubmed and Web of Science database for the period 1960-2012. Inclusion criteria were: 1) Measurement of at least one production parameter. 2) Comparison between groups of sheep with different nematode burdens. 3) Same conditions regarding all aspects except parasite burden between groups. 4) Quantitative measurements of one or more production traits. RESULTS: Altogether, 88 studies describing 218 trials were included in this review. The majority of studies (86%) reported that GIN infections had a negative effect on production but this was reported to be statistically significant in only 43% of the studies. Meta-analysis indicated that performances of sheep infected with nematodes was 85, 90 and 78% of the performance in uninfected individuals for weight gain, wool production and milk yield respectively. Our results suggest a possible reporting bias or small study effect for the estimation of the impact of GIN infections on weight gain. Finally, a general linear model provided an estimate for the decrease in weight gain in relation to the increase in faecal egg count of nematodes. CONCLUSION: This study underlines the importance of GIN infections for sheep production and highlights the need to improve parasite management in sheep, in particular in face of challenges such as anthelmintic resistance.

Inhibition of Haemonchus contortus larval development by fungal lectins.

BACKGROUND: Lectins are carbohydrate-binding proteins that are involved in fundamental intra- and extracellular biological processes. They occur ubiquitously in nature and are especially abundant in plants and fungi. It has been well established that certain higher fungi produce lectins in their fruiting bodies and/or sclerotia as a part of their natural resistance against free-living fungivorous nematodes and other pests. Despite relatively high diversity of the glycan structures in nature, many of the glycans targeted by fungal lectins are conserved among organisms of the same taxon and sometimes even among different taxa. Such conservation of glycans between free-living and parasitic nematodes is providing us with a useful tool for discovery of novel chemotherapeutic and vaccine targets. In our study, a subset of fungal lectins emanating from toxicity screens on Caenorhabditis elegans was tested for their potential to inhibit larval development of Haemonchus contortus. METHODS: The effect of Coprinopsis cinerea lectins - CCL2, CGL2, CGL3; Aleuria aurantia lectin - AAL; Marasmius oreades agglutinin - MOA; and Laccaria bicolor lectin - Lb-Tec2, on cultivated Haemonchus contortus larval stages was investigated using a larval development test (LDT). To validate the results of the toxicity assay and determine lectin binding capacity to the nematode digestive tract, biotinylated versions of lectins were fed to pre-infective larval stages of H. contortus and visualized by fluorescent microscopy. Lectin histochemistry on fixed adult worms was performed to investigate the presence and localisation of lectin binding sites in the disease-relevant developmental stage. RESULTS: Using an improved larval development test we found that four of the six tested lectins: AAL, CCL2, MOA and CGL2, exhibited a dose-dependent toxicity in LDT, as measured by the number of larvae developing to the L3 stage. In the case of AAL, CGL2 and MOA lectin, doses as low as 5 µg/ml caused >95 % inhibition of larval development while 40 µg/ml were needed to achieve the same inhibition by CCL2 lectin. MOA was the only lectin tested that caused larval death while other toxic lectins had larvistatic effect manifesting as L1 growth arrest. Using lectin histochemistry we demonstrate that of all lectins tested, only the four toxic ones displayed binding to the larvae's gut and likewise were found to interact with glycans localized to the gastrodermal tissue of adults. CONCLUSION: The results of our study suggest a correlation between the presence of target glycans of lectins in the digestive tract and the lectin-mediated toxicity in Haemonchus contortus. We demonstrate that binding to the structurally conserved glycan structures found in H. contortus gastrodermal tissue by the set of fungal lectins has detrimental effect on larval development. Some of these glycan structures might represent antigens which are not exposed to the host immune system (hidden antigens) and thus have a potential for vaccine or drug development. Nematotoxic fungal lectins prove to be a useful tool to identify such targets in parasitic nematodes.

Sheep and Fasciola hepatica in Europe: the GLOWORM experience.

Fasciola hepatica infection challenges health, welfare and productivity of small ruminants throughout the world. The distribution of F. hepatica in sheep in Europe is usually scattered and studies are generally concerned with a single area making it difficult to compare results from different environments, climates and management regimes. In order to elucidate the current scenario in terms of prevalence and intensity of F. hepatica infection in sheep farms across Europe, a standardized cross-sectional survey was conducted in three pilot areas in Ireland, Switzerland and Italy, all part of the EU funded GLOWORM project. Two consecutive field surveys (in 2012 and 2013) were conducted in the three countries in the same period (August-October) in 361 sheep farms in total. Harmonized procedures (from farm to laboratory) based on pooled samples and the highly sensitive and accurate, diagnostic FLOTAC technique were used. The georeferenced parasitological results were modelled (at the pilot area level) following a Bayesian geostatistical approach with correction for preferential sampling and accounting for climatic and environmental covariates. The observed F. hepatica prevalence rates did not differ between the two study years in any of the three pilot areas, but they did vary between the countries showing high values in Ireland (61.6%) compared to Italy (7.9%) and Switzerland (4.0%). Spatial patterns of F. hepatica distribution were detected by the Bayesian geostatistical approach in Ireland with a high risk of infection in the south-western part of the pilot area there. The latent factor analysis highlighted the importance of year-to-year variation of mean temperature, rainfall and seasonality within a country, while long-term trends of temperature and rainfall dominated between countries with respect to prevalence of infection.

Haemonchus contortus: spatial risk distribution for infection in sheep in Europe.

Haemonchus contortus is a species of gastrointestinal strongyles of primary concern for sheep. This highly pathogenic, blood-feeding helminth negatively influences animal health, welfare and productivity. In order to elucidate the current scenario in terms of prevalence and intensity of H. contortus infection in sheep farms across Europe, a standardized crosssectional survey was conducted in three pilot areas in Ireland, Switzerland and Italy, all part of the EU funded GLOWORM project. Two consecutive field surveys (in 2012 and 2013) were conducted in the three countries in the same period (August-October) in 259 sheep farms in total. Harmonized, diagnostic procedures (from farm to laboratory) based on pooled samples, the FLOTAC technique and coproculture were used. The georeferenced parasitological results were modelled (at the pilot area level) following a Bayesian geostatistical approach with correction for preferential sampling and accounting for climatic and environmental covariates. The observed H. contortus prevalence rates did vary between the countries showing high values in Switzerland (77%) and Italy (73%) compared to Ireland (4%). Spatial patterns of H. contortus distribution were detected in Switzerland and Italy with a north-south gradient. The latent factor analysis highlighted the importance of seasonality and annual cyclicity within country (particularly in southern Italy), while mean temperature and rainfall dominated between country variations in the prevalence of H. contortus infection.

Frequency of eprinomectin resistance in gastrointestinal nematodes of goats in canton Berne, Switzerland.

Eprinomectin (EPN) is a member of the avermectin class of compounds and the only anthelmintic registered for goats in Switzerland with a zero milk withdrawal period. The aim of the present study was to identify the actual efficacy of EPN in an area with a higher density of goat enterprises. Forty-three randomly chosen farms from canton Berne were investigated. At least eight goats were investigated on every farm. Conditions for inclusion in the study were the absence of anthelmintic treatment during the previous six weeks and a pooled faecal sample showing a mean faecal egg count (FEC) higher than 600 epg faeces. Pre- and 14-16 days post-treatment samples were individually collected directly from the rectum. Animals were treated with the recommended dose of EPN (1 mg/kg body weight) after taking the pre-treatment samples. Efficacy of EPN was tested with the faecal egg count reduction test (FECRT) and faecal cultures were performed on every farm from pooled faeces samples before and after treatment. Additionally the farmers completed a questionnaire. None of the gastrointestinal nematode populations of the 43 investigated farms were susceptible to EPN at the required level. The mean egg count reduction was 40%. None of the typical risk factors, such as production type, stocking rate, animal traffic and quarantine measures showed an association with the level of eprinomectin resistance. It can be concluded with 80% certainty that the prevalence of EPN resistance on goat farms is at least 95% in canton Berne.

Genetics, chromatin diminution, and sex chromosome evolution in the parasitic nematode genus Strongyloides.

BACKGROUND: When chromatin diminution occurs during a cell division a portion of the chromatin is eliminated, resulting in daughter cells with a smaller amount of genetic material. In the parasitic roundworms Ascaris and Parascaris, chromatin diminution creates a genetic difference between the soma and the germline. However, the function of chromatin diminution remains a mystery, because the vast majority of the eliminated DNA is noncoding. Within the parasitic roundworm genus Strongyloides, S. stercoralis (in man) and S. ratti (in rat) employ XX/XO sex determination, but the situation in S. papillosus (in sheep) is different but controversial. RESULTS: We demonstrate genetically that S. papillosus employs sex-specific chromatin diminution to eliminate an internal portion of one of the two homologs of one chromosome pair in males. Contrary to ascarids, the eliminated DNA in S. papillosus contains a large number of genes. We demonstrate that the region undergoing diminution is homologous to the X chromosome of the closely related S. ratti. The flanking regions, which are not diminished, are homologous to the S. ratti autosome number I. Furthermore, we found that the diminished chromosome is not incorporated into sperm, resulting in a male-specific transmission ratio distortion. CONCLUSIONS: Our data indicate that on the evolutionary path to S. papillosus, the X chromosome fused with an autosome. Chromatin diminution serves to functionally restore an XX/XO sex-determining system. A consequence of the fusion and the process that copes with it is a transmission ratio distortion in males for certain loci.

Individual administration of three tanniferous forage plants to lambs artificially infected with Haemonchus contortus and Cooperia curticei.

We investigated direct anthelmintic effects associated with the feeding of fresh tanniferous forages against established populations of Haemonchus contortus and Cooperia curticei in lambs. Twenty-four parasite naive lambs were inoculated with a single dose of infective larvae of these two parasites 27 days prior to the start of the feeding experiment. Lambs were individually fed with either chicory (Cichorium intybus), birdsfoot trefoil (Lotus corniculatus), sainfoin (Onobrychis viciifolia) or a ryegrass/lucerne mixture (control) for 17 days. Animals where then united to one flock and subjected to control feeding for another 11 days to test the sustainability of potentially lowered egg excretion generated by tanniferous forage feeding. When compared to the control, administration of all tanniferous forages was associated with significant reductions of total daily faecal egg output specific to H. contortus (chicory: 89%; birdsfoot trefoil: 63%; sainfoin: 63%; all tests P<0.05) and a tendency of reduced H. contortus worm burden (chicory: 15%; birdsfoot trefoil: 49% and sainfoin: 35% reduction). Irrespective of the condensed tannin (CT) containing fodder, no anthelmintic effects were found against C. curticei. Cessation of CT-feeding followed by non-CT control feeding did not result in a re-emergence of faecal egg counts based on faecal dry matter (FECDM) in any group, suggesting that egg output reductions are sustainable. The moderate to high concentrations of CTs in birdsfoot trefoil (15.2 g CTs kg(-1) dry matter (DM)) and sainfoin (26.1 g CTs kg(-1) DM) were compatible with the hypothesis that the antiparasitic effect of these forages is caused by their content of CTs. For chicory (3 g CTs kg(-1) DM), however, other secondary metabolites need to be considered. Overall, birdsfoot trefoil and in particular sainfoin seem promising candidates in contributing to an integrated control strategy against H. contortus not only by mitigating parasite related health disturbances of the host but also by a sustained reduction of pasture contamination.

Prevalence and significance of gastrointestinal helminths and protozoa in South American Camelids in Switzerland.

A cross sectional study was conducted to determine the prevalence and significance of endoparasitic infections in South American Camelids (SAC) in Switzerland. Qualitative and quantitative coproscopic examinations were performed in 38 farms during the grazing period. Management practices with possible interference with parasitic infections were analyzed. On the farm level prevalences of endoparasitic infections were: trichostrongyles 87%; Trichuris sp. 74%; Capillaria sp. 68%; Nematodirus battus 63%; Nematodirus sp. 53%; Dicrocoelium dendriticum 34%; Moniezia sp. 8%; Fasciola hepatica 5%; protostrongylids 5%; Eimeria macusaniensis 68%. The level of helminth egg excretion was generally low. The highest values were recorded for trichostrongyles with an average of all investigated farms of 53 eggs per gram of faeces. The mean trichostrongyle egg output was approximately three-fold in SAC on farms that also kept sheep and/or goats, although this difference was not significant (P = 0.11). Clinical trichostrongylidosis was not reported from any of the farms. The low infection level with gastrointestinal nematodes is attributed to the defaecation behaviour of the SAC depositing their faeces focally on small spots on pasture. As a consequence, pasture infectivity is largely restricted to the area adjacent to the dung piles. Dicrocoeliosis is regarded as the most relevant parasitic infection of llamas and alpacas in Switzerland causing severe clinical symptoms and death in untreated animals. Sixteen per cent of the owners regularily treated their herds against dicrocoeliosis using praziquantel at a dose of 50 mg/kg body weight orally.

Effect of sainfoin (Onobrychis viciifolia) silage and hay on established populations of Haemonchus contortus and Cooperia curticei in lambs.

The objective of the study was to examine the effect of dried and ensiled sainfoin (Onobrychis viciifolia) on established populations of Haemonchus contortus (abomasum) and Cooperia curticei (small intestine) in lambs under controlled conditions. Twenty-four parasite naïve lambs were inoculated with a single dose of infective larvae of these parasites 28 days prior to the start of the feeding experiment. Twenty-four days post-infection, 4 days prior to the start of the feeding experiment, animals were allocated to four groups according to egg excretion, live weight and sex. Groups A and B received sainfoin hay and control hay, respectively, for 16 days. Groups C and D were fed on sainfoin silage or control silage for the same period. Feeds were offered ad libitum and on the basis of daily refusals were supplemented with concentrate in order to make them isoproteic and isoenergetic. Individual faecal egg counts on a dry matter basis (FECDM) were performed every 3-4 days and faecal cultures and packed cell volume (PCV) measurements were done weekly. After 16 days of experimental feeding, all animals were slaughtered and adult worm populations were determined. The consumption of conserved sainfoin was associated with a reduction of adult H. contortus (47% in the case of hay, P<0.05; 49% in the case of silage, P=0.075) but had little effect on adult C. curticei. Compared to the controls, H. contortus specific FECDM was reduced by 58% (P<0.01) in the sainfoin hay group and by 48% (P=0.075) in the sainfoin silage group. For both sainfoin feeds FECDM specific to C. curticei were significantly decreased when compared to the control feeds (hay 81% and silage 74%, both tests P<0.001). Our data suggest that different mechanisms were responsible for the reduction in FECDM in response to feeding tanniferous fodder. For H. contortus, the decrease seemed to be due to a nematocidal effect towards adult H. contortus. In contrast for C. curticei, the reduction in FECDM appeared to be a result of a reduced per capita fecundity. For both, hay and silage, an antiparasitic effect could be shown, offering promising perspectives for the use of conserved tanniferous fodder as a complementary control approach against GIN.

[Biological control of helminths in grazing animals using nematophagous fungi]. / Biologische Helminthenkontrolle bei Weidetieren mit nematophagen Pilzen.

For the last 50 years the control of gastro-intestinal nematodes (GIN) in grazing animals has almost entirely been alleviated by the use of anthelmintics. Due to development of resistance against the drugs, especially in the GIN of sheep and goats it has become necessary to develop new, innovative strategies such as the use of nematode destroying fungi. Despite experiments to employ various species against plant and animal parasitic nematodes were already attempted in the 1930's, it was not until the 1990's when selection by simulating passage through the gastro-intestinal tract of cattle led to isolation of the fungus Duddingtonia flagrans that a major breakthrough was achieved. This fungus, producing sticky three-dimensional network and now isolated world-wide, is special due to its capacity to prolifically produce high numbers of thick-walled resting spores, chlamydospores. These spores survive passage through the gastro-intestinal tract of grazing livestock and are capable of growing and subsequently trap nematodes, including larval stages of parasitic nematodes. The great potential of this fungus as a biological control agent has been demonstrated through numerous trials with cattle, sheep, horses, and pigs. But these trials have also pointed towards some potential limitations in the activity spectrum of the fungus (Dictyocaulus, Nematodirus) beside the whole group of parasites spreading through infective stages protected inside resistant eggs (e.g. Ascaris, Trichuris). So far, in the few reported studies conducted, no negative environmental impact has been found, but it is important that further studies are conducted on this important issue. Although the potential use of D. flagrans chlamydospores has been verified through numerous trials it is necessary to develop practical delivery systems such as slow release devices, feed-blocks or similar to be able to implement this tool in future integrated control strategies. Such control strategies could include the use of biological control, grazing management, smart use of existing drugs, parasite resistant animal breeds, bioactive forages, and possibly vaccines.