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12 páginas, 4 figuras, 4 tablas., We report a European wide assessment of the economic burden of gastrointestinal nematodes, Fasciola hepatica (common liver fluke) and Dictyocaulus viviparus (bovine lungworm) infections to the ruminant livestock industry. The economic impact of these parasitic helminth infections was estimated by a deterministic spreadsheet model as a function of the proportion of the ruminant population exposed to grazing, the infection frequency and intensity, the effect of the infection on animal productivity and mortality and anthelmintic treatment costs. In addition, we estimated the costs of anthelmintic resistant nematode infections and collected information on public research budgets addressing helminth infections in ruminant livestock. The epidemiologic and economic input data were collected from international databases and via expert opinion of the Working Group members of the European Co-operation in Science and Technology (COST) action COMbatting Anthelmintic Resistance in ruminants (COMBAR). In order to reflect the effects of uncertainty in the input data, low and high cost estimates were obtained by varying uncertain input data arbitrarily in both directions by 20 %. The combined annual cost [low estimate-high estimate] of the three helminth infections in 18 participating countries was estimated at € 1.8 billion [€ 1.0–2.7 billion]. Eighty-one percent of this cost was due to lost production and 19 % was attributed to treatment costs. The cost of gastrointestinal nematode infections with resistance against macrocyclic lactones was estimated to be € 38 million [€ 11–87 million] annually. The annual estimated costs of helminth infections per sector were € 941 million [€ 488 – 1442 million] in dairy cattle, € 423 million [€ 205–663 million] in beef cattle, € 151million [€ 90–213 million] in dairy sheep, € 206 million [€ 132–248 million] in meat sheep and € 86 million [€ 67–107 million] in dairy goats. Important data gaps were present in all phases of the calculations which lead to large uncertainties around the estimates. Accessibility of more granular animal population datasets at EU level, deeper knowledge of the effects of infection on production, levels of infection and livestock grazing exposure across Europe would make the largest contribution to improved burden assessments. The known current public investment in research on helminth control was 0.15 % of the estimated annual costs for the considered parasitic diseases. Our data suggest that the costs of enzootic helminth infections which usually occur at high prevalence annually in ruminants, are similar or higher than reported costs of epizootic diseases. Our data can support decision making in research and policy to mitigate the negative impacts of helminth infections and anthelmintic resistance in Europe, and provide a baseline against which to measure future changes., This article is based upon work from COST Action COMBAR CA16230, supported by COST (European Cooperation in Science and Technology) and from the Livestock helminth Research Alliance (LiHRA). HRV and ERM are supported by the BBSRC BUG (Building on the Genome) sLoLa project (grant ref: BB/M003949/1, and BB/ R010250/1). HRV is also supported by the University of Liverpool’s Institute of Infection and Global Health. MMV was funded by the Spanish “Ramón y Cajal” Programme, Ministry of Economy and Competitiveness (Ministerio de Economía y Competitividad; RYC-2015-18368).

In a survey involving 34 sheep flocks spread over the Netherlands anthelmintic resistance (AR), based on a fecal egg count reduction (FECR) test, was determined for six different products. The study was conducted in ewes shortly after lambing during spring 2015. A FECR of less than 90%, indicating presence of AR against one or more nematode genera producing strongylid eggs, was found in 22 of 30 (73.3%) flocks against oxfendazole, 18 of 23 (78.3%) flocks against ivermectin, 15 of 32 (46.9%) flocks against moxidectin, and 2 of 26 (7.7%) flocks against monepantel. No AR was observed against levamisole. If oxfendazole resistance was observed, Haemonchus contortus was involved in 90.5% of the cases. If resistance against ivermectin, moxidectin or monepantel was observed, it invariably involved H. contortus. In the majority of cases resistance was also observed for Teladorsagia circumcincta and/or Trichostrongylus spp, between which no distinction was made in this study. Based on FECR 9 of 15 (60.0%) flocks showed resistance against closantel, which was mainly due to closantel not being effective against most other nematode species than H. contortus. However, in 44.4% of flocks showing reduced FECR it did involve H. contortus as well. Multi-drug resistance (excluding closantel) was found in 16 flocks, of which 8 showed resistance against 2 products, 7 against 3 products and 1 flock showed resistance against 4 products. If resistance against 3 or 4 products was present, there invariably was resistance against both ivermectin and moxidectin. Overall, of the 22 flocks in which both macrocyclic lactones (ML) were tested, 4 (18.2%) showed no resistance against both products, 9 (40.9%) showed resistance against ivermectin only, and 9 (40.9%) showed resistance against both MLs. It is concluded that AR is widespread in sheep in the Netherlands and involves products from all major anthelmintic classes, with possibly the exception of levamisole. It appears that the macrocyclic lactones have lost much of their efficacy against sheep nematodes over the last decade.

The purpose of the study was to gain knowledge about the prevalence and identity of rumen flukes (RF) in cattle and sheep in the Netherlands. Routine faecal examinations of diagnostic submissions between May 2009 and September 2014 showed a mean annual herd or flock RF prevalence of 15.8% for cattle and 8.0% for sheep. Prevalence in cattle was higher after 2012 than before, which may reflect a change in detection method as well as an increase in true prevalence. During November and December 2014, an abattoir survey was conducted to allow for scoring of rumen fluke burden and to obtain specimens for molecular species characterization. Over 8 visits to 5 abattoirs in areas deemed to pose a high risk for trematode infection, 116 cows and 41 sheep from 27 herds and 10 flocks were examined. Prevalence of RF was higher in beef cattle than in dairy cattle and higher in cattle than in sheep. Median fluke burden was >100 specimens per animal for most positive animals.\ud \ud Using a semi-quantitative RF density score as a gold standard, sensitivity and specificity of a modified quantitative Dorsman egg counting method were estimated at 82.6% and 83.3%, respectively.\ud Of 14 collected adult rumen flukes, twelve (8 bovine and 4 ovine specimens) were identified as Calicophoron daubneyi. The other two, of bovine origin, were identified as Paramphistomum leydeni, which was unexpected as in other European countries all recently collected rumen flukes in both cattle and sheep were identified as C. daubneyi. The findings implicate that multiple rumen fluke species, intermediate host species and transmission cycles may play a role in rumen fluke infections in the Netherlands.

Gastrointestinal (GI) nematode infections are considered among one of the toughest challenges sheep farmers face worldwide. Control still is largely based on the use of anthelmintics, but anthelmintic resistance is becoming rampant. To facilitate implementation of alternative nematode control strategies and to reduce anthelmintic usage, the purpose of this study was twofold: (i) to gain insight in common practices, knowledge gaps and perceptions of farmers regarding nematode control, and (ii) to provide foci of attention for improving parasite control practices and transfer of knowledge within the sheep husbandry. An internet-based questionnaire was made available to all sheep farmers pertaining to the year 2013, resulting in 450 entered questionnaires for analysis.The two most important nematodes mentioned, were Haemonchus contortus and, to a lesser extent, Nematodirus battus. Of all respondents, 25.6% said they did not have any worm problems. Of these, almost a third did notice clinical signs that can be related to worm infections and about three quarters did use anthelmintics. Overall, clinical symptoms mentioned by farmers matched the worm species they identified as the cause of problems.Ewes and lambs were treated up to 6 times in 2013. On average, ewes were treated 1.53 and lambs 2.05 times. Farmers who treated their ewes more often, also treated their lambs more often (P

A study was conducted to evaluate the occurrence of resistance against, in particular, ivermectin in cyathostomins in the Netherlands. Seventy horse farms were visited between October 2007 and November 2009. In initial screening, faecal samples were collected 2 weeks after deworming with either ivermectin, moxidectin or doramectin. Pooled faecal samples from a maximum of 10 horses were examined for worm eggs using a modified McMaster technique and for worm larvae after faecal larval cultures. In total 931 horses were involved. On 15 of 70 farms eggs and/or larvae were found. On 8 of these 15 farms a FECRT with ivermectin was performed on 43 horses. Efficacy of ivermectin against cyathostomins of 93% was found in one animal on one farm. Additionally, the strategies and efforts of the horse owners to control cyathostomins, as well as risk factors for the development of macrocyclic lactone resistance were evaluated with a questionnaire. Strikingly, many responders indicated that the control of cyathostomins in horses is achieved through very frequent deworming. Fourteen percent of these owners deworm seven times per year or more. On 34% of the 70 farms treatment was repeated within the Egg Reappearance Period of a product.

Cyathostomins are considered to be the primary helminth pathogen of horses and macrocyclic lactones (ML) are the most frequently used anthelmintics. Therefore, ML resistance is a serious threat for the control of these parasites. In the present study ivermectin resistant cyathostomin L3 were in vitro selected, using a reiterative larval migration inhibition assay (rLMIA) and differentiated by reverse line blot (RLB). Larvae were obtained from two populations, one from a never treated, free-roaming horse population in the nature reserve Oostvaardersplassen (OVP) and the other from regularly ivermectin-treated ponies of Utrecht University (UU). In the rLMIA the proportion of larvae that migrated increased with each passage, demonstrating that the applied procedure indeed selects for larvae the least susceptible for ivermectin. This was further supported by the fact that glutamate addition to this procedure reversed the selection effect, which also suggests that glutamate-gated chloride channels (GluCls) play a role in the ivermectin resistance of the selected L3. In both populations the predominant species were Cyathostomum catinatum, Cylicostephanus longibursatus and Cylicocyclus nassatus. After in vitro selection in the rLMIA in the presence of ivermectin the predominant species became C. catinatum in both larval populations, while C. nassatus disappeared in the never treated OVP larval population but not in the regularly ivermectin-exposed UU population. It is concluded that the rLMIA and RLB can be used to study anthelmintic resistance in cyathostomin populations and to study differences and changes in species composition between populations with different anthelmintic exposure histories.

The normal time interval between treatment of horses with a macrocyclic lactone (ML) and reappearance of strongyle eggs in the feces, or 'Egg Reappearance Period (ERP)', is at its shortest 8 weeks for ivermectin (IVM) and 12 weeks for moxidectin (MOX). Nowadays, it is not uncommon to find shorter ERPs, potentially indicating the beginning of the development of drug resistance. Whether all cyathostomin species contribute equally to a shortened ERP is not known. In the present study a Reverse Line Blot (RLB) on individual infective larvae was used to compare species composition before and after ML-treatment in horses with either a normal or a shortened ERP. Species composition was determined for a total of 21 horses on 4 farms and was based on differentiation of approximately 40 larvae per horse per sampling day. After IVM treatment the shortest ERP was found to be 28-42 days. After MOX treatment the shortest ERP was found to be 42-56 days. The RLB showed that early egg shedding was dominated by species of the genus Cylicocyclus (Cyc.) (Cyc. ashworthi, Cyc. insigne, Cyc. leptostomum and Cyc. nassatus). Before treatment, species composition was generally more diverse with species from several other genera also present. Interestingly, on the farm with the overall shortest ERP and where all horses showed a shortened ERP, more species/genera were present during early egg excretion than on other farms. Results suggest that cyathostomin species within the genus Cylicocyclus contribute to a shortened ERP more than species from other genera. However, if shortening of ERP overall becomes more pronounced and widespread within a farm, species from other genera will also be present during early egg shedding.

In two experiments groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including a normal or a delayed midsummer increase, under conditions of set-stocking. The purpose of the experiments was to investigate the accuracy of egg counts, pepsinogen and gastrin values and antibody titres as estimators of the level of exposure to infection. Faecal egg counts significantly reflected levels of exposure during the first half of the simulated grazing season. Antibody titres and pepsinogen values reflected levels of exposure best during August and September, partly depending on the pattern and range of levels of exposure. Antibody titres against Cooperia spp. were particularly useful when levels of exposure to gastrointestinal nematode infection were low. Gastrin values were elevated only at high levels of exposure, which caused large weight gain reductions, in the later part of the simulated first grazing season. It is suggested that antibody titres and pepsinogen values can be used for prognostic diagnosis, indicating whether or not control measures should be taken. Both estimators of infection correlated significantly with the realised weight gain at the end of the simulated grazing season. Egg counts in the second month after the initial infection (turnout) also may be of significant value to support decisions concerning control measures. Comparisons with data from field trials and experiments conducted by others under various conditions suggested that the conclusions of the present experiments are also valid under field conditions. Furthermore, the results supported the conclusions drawn from previous field work, that levels to exposure are often very low on commercial farms in the Netherlands.