Nematodirus Battus Research Articles

Health Impact of Co-Infestation with Gastrointestinal Helminthes Parasites in Cattle in Bangangté Subdivision, West Cameroon

There is growing interest in the scientific community about co-infestations and the determinism of their synergistic action against their hosts, in a prospect of improving animal survival rates and production. A big number of parasitic associations have been tested, most of which include parasites belonging to radically different systematic groups. This study measures the impact of gastro-intestinal parasitic associations in bovines on two health parameters: the PCV and the body condition score. To this end, we conducted a survey in the district of Bangangte from May to July 2022. Six (06) cattle farms (Bos taurus) were selected for a total of 300 animals. Blood, Fecal matter collection and careful visual observation for Body score condition recording took place on each animal part of the study. Lab analysis of fecal matters revealed eggs of 11 parasitic helminths species and their respective prevalences was calculated. The species whose eggs were discovered are: Haemonchus contortus (from 44,67 % of animals), Fasciola gigantica (38,33%), Trichostrongylus axei (13,33%), Nematodirus battus (8,33%), Ostertagia ostertagi (7,67 %), Cooperia spp. (6,00%), Strongyloïdes papillosus (4,00%), Paramphistomum cervi (3,67%), Moniezia benedeni (1,33%), Toxocara vitulorum (0,67 %) and Trichuris spp (0,33%). We found that 70,6% of animals was infested with at least one parasite, while 42% presented at least two parasites. The combinations of parasites having the most negative effect on the hematocrit level were composed of: O. ostertagi, Cooperia spp and Strongyloides papillosus. The one reducing the body condition score the most was the association of Ostertagia ostertagi and Strongyloides papillosus. More studies in a controlled environment, with artificial infestations, are required to confirm the adverse effects of parasitic associations delighted in this study.

Refugia, climatic conditions and farm management factors as drivers of adaptation in Nematodirus battus populations

Parasites are known for their ability to rapidly adapt to changing conditions. For parasitic helminths, changes in climate, along with farming and management practices associated with the intensification of livestock farming, provide novel challenges which can impact on their epidemiology and control. The sustainability of livestock production partially relies on effective control of helminth infection. Therefore, understanding changes in parasite behaviour, and what drives these, is of great importance. Nematodirus battus is an economically important helminth in the UK and temperate regions. Its infective larvae typically overwinter in eggs on pasture and hatch synchronously in spring, causing acute disease in lambs. Attempts to control disease typically rely on whole-flock benzimidazole (BZ) treatments. In recent years, the emergence of BZ-resistance, alongside the hatching of eggs without the classical over-winter ‘chill stimulus’, have made N. battus more difficult to control. In three previous studies, after collecting a large number of N. battus populations alongside farm management data from commercial farms, we explored the prevalence of genetic mutations associated with BZ-resistance (n = 253 farms), the ability of eggs to hatch with and without a chill stimulus (n = 90 farms) and how farm management practices varied throughout the UK (n = 187 farms). In the present study, we identify factors which may be acting as drivers, or barriers, to either the development of resistance or the variable hatching behaviour of N. battus eggs. Generalised linear mixed effect models were applied to regress experimental hatching and genotyping data on farm management and additional environmental data. Both variable hatching and resistance development appeared associated with the maintenance of parasite refugia as well as grazing management, particularly reseeding of pasture routinely grazed by young lambs each spring and the practice of set-stocked grazing. Effective quarantine measures were identified as the main protective factor for the development of BZ-resistance whereas set stocked grazing and population bottlenecks, resulting from reseeding heavily contaminated pastures, were risk factors. Spring maximum temperature and other climatic factors were associated with ‘typical’ hatching of eggs following a chill stimulus whilst several management factors were linked with hatching without prior chilling. For example, practices which reduce parasite numbers on pasture (e.g. re-seeding) or restrict availability of hosts (e.g. resting fields), were found to increase the odds of non-chill hatching. Retention of the timing of lambing and infection level of the host within the fitted model indicated that requirement for a chill stimulus prior to hatching may be plastic, perhaps subject to change throughout the grazing season, in response to immune development or parasite density-dependence within the host. Further investigation of the influence of the factors retained within the fitted models, particularly the theme of parasite refugia which was highlighted in relation to both the presence of BZ-resistance alleles and alternative hatching, is required to establish robust, sustainable parasite control and farm management strategies.

Parasite Spillover from Domestic Sheep to Wild Reindeer—The Role of Salt Licks

Attraction sites are important for environmental pathogen transmission and spillover. Yet, their role in wildlife disease dynamics is often poorly substantiated. Herein, we study the role of salt licks as potential attraction sites for the spillover of gastrointestinal parasites from domestic sheep to wild reindeer. Eggs from the introduced sheep nematode Nematodirus battus were found in faecal samples of both species, suggestive of spillover. DNA metabarcoding of soil, collected at salt licks, revealed that N. battus, in addition to Teladorsagia circumcincta, were the most frequently occurring parasitic nematodes, with a significantly higher prevalence of nematodal DNA in salt lick soil compared to soil from control sites nearby. The finding of similar DNA haplotypes of N. battus in sheep, reindeer, and salt lick soil supports the hypothesis of spillover to reindeer via salt licks. More detailed investigation of the genetic diversity of N. battus across these hosts is needed to draw firm conclusions. Infection with these sheep nematodes could potentially explain a recently observed decline in the calf recruitment rate of the Knutshø reindeer herd. This study also supports the hypothesized role of artificial salt licks as hot spots for the transmission of environmentally persistent pathogens and illustrates the importance of knowledge about such attraction points in the study of disease in free-roaming animals.

Two Centrifugal Flotation Techniques for Counting Gastrointestinal Parasite Eggs and Oocysts in Alpaca Faeces.

The alpaca (Vicugna pacos) is a camelid native to South America, but the species has wide distribution outside its natural habitat and is found in various countries on other continents, Poland being one in Europe. Parasitic infections affect the productivity and health of alpacas. The aim of the study was to estimate the parasite loads in alpacas kept in Poland with the use of two direct centrifugal flotation methods. A total of 248 faecal samples from alpacas from 12 provinces in Poland were examined for parasite eggs and oocysts with a modified Willis method (WM), and 59 samples were examined simultaneously with WM and a modified Stoll method (SM). The WM detected eggs of Trichostrongylidae, and the SM oocysts of Eimeria spp. as the respective most prevalent parasite material. The eggs of Nematodirus sp., Nematodirus battus, Aonchotheca sp., and Trichuris sp. were detected in lower numbers in both methods. Oocysts of E. macusaniensis and eggs of Moniezia sp. were the rarest in WM, the former also being so in SM; eggs of Moniezia were absent in SM. The prevalence of Eimeria spp. was significantly higher as detected by SM than as detected by WM; however, the prevalence of eggs of Nematodirus spp. and trichostrongyles was significantly higher as detected by WM than as detected by SM. WM is more accurate at detecting heavy gastro-intestinal nematode eggs, including those of trichostrongyles and Nematodirus, whereas SM is more accurate at detecting smaller coccidia from the genus Eimeria.

Changing patterns of Nematodirus battus infection

Nematodirus battus is a gastrointestinal parasite which has a huge impact in UK sheep flocks as a result of lamb mortality and reduction in growth. Farmers and veterinary surgeons conventionally focus their efforts on preventing outbreaks of nematodirosis during the spring, but the incidence of autumn infections is a growing concern. The aim of this article is to highlight the changes in the behaviour of N. battus and provide some guidance on how to approach the challenges that this creates.

Naturally acquired ovine-adapted nematode infections in young cattle and their treatment with eprinomectin 5% w/v extended-release injection.

The objective of this controlled study was to determine the anthelmintic efficacy of eprinomectin 5% w/v extended-release injection (Eprinomectin ERI; LONGRANGE®, Boehringer Ingelheim Animal Health) against primarily ovine-adapted gastrointestinal strongylid nematode (GIN) parasites in naturally infected young cattle. Eighteen calves which grazed on a sheep-dominated mixed sheep-cattle farm were randomly allocated into two equal groups (saline [control] or Eprinomectin ERI, administered each at 1mL/50kg body weight once subcutaneously), treated and euthanized 14days thereafter for a differential GIN count. Ten species of strongylid nematodes were recovered from the control calves (ovine-adapted Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis, Cooperia curticei, Nematodirus battus, Chabertia ovina; bovine-adapted Ostertagia ostertagi, Cooperia oncophora, Nematodirus helvetianus; 'generalist' Trichostrongylus axei). Adult GIN counts ranged from 1,540 to 5,244 for the control calves and from zero to 110 for the Eprinomectin ERI-treated calves. Accepting the International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products anthelmintic guidelines criteria on adequacy of infections to be demonstrated in the control animals, this study showed that Ch. ovina, C. curticei, H. contortus, N. battus, T. axei, and T. colubriformis were reduced significantly (p < 0.0001) by ≥ 98.7% in the animals treated with Eprinomectin ERI. In conclusion, Eprinomectin ERI treatment was efficacious against a range of ovine-adapted nematode parasites in naturally infected young cattle.

The heritability of Nematodirus battus fecal egg counts.

Although Nematodirus battus is a serious threat to the health and survival of young lambs, there are few options to control this parasite. Bayesian Monte Carlo Markov Chain modelling with a zero-inflated Poisson distribution was used to estimate the heritability of egg counts in both June and July for each of five consecutive cohorts of 200 Scottish Blackface lambs. In one of the 10 analyses, the results failed the diagnostic tests. In seven of the analyses, there was no convincing evidence that the variation in egg counts was heritable. In the 2 years of high infection, the heritability was approximately 0.4 in June but the estimates lacked precision and the 95% highest posterior density credible intervals ranged from just above zero to 0.7. Selective breeding for resistance to N. battus will be difficult because genetically resistant or susceptible lambs cannot be consistently identified by phenotypic markers.

Pour-on administration of eprinomectin to lactating dairy goats: Pharmacokinetics and anthelmintic efficacy.

Lactation is discussed as a physiological covariate which may influence the exposure characteristics of systemically acting drugs including macrocyclic lactones and potentially alter their pharmacological response. This study characterizes for the first time in the same study, the plasma profile and therapeutic anthelmintic efficacy of eprinomectin 5mg/ml solution (EPRINEX® Multi, Boehringer Ingelheim) administered as a pour-on at 1mg per kg body weight to lactating dairy goats. The study was conducted in compliance with VICH GCP and anthelmintic efficacy evaluation guidelines and included 20goats harboring induced adult gastrointestinal and pulmonary nematode infections. The goats were blocked on pre-treatment body weight and randomly allocated either to remain untreated (control) or to be eprinomectin-treated. Plasma samples to determine the plasma disposition kinetics of eprinomectin (B1a component) were obtained at intervals up to 14days following treatment when the animals were necropsied for parasite enumeration and identification. Basic pharmacokinetic parameters of eprinomectin determined in the ten eprinomectin-treated goats were as follows: AUClast , 23.8±9.7day*ng/ml and Cmax , 5.35±2.27ng/ml; individual maximum plasma concentrations were observed from 8 to 48h after treatment (median Tmax , 0.5days). Topical eprinomectin treatment efficacy, based on significant (p<.01) worm burden reductions in eprinomectin-treated animals relative to untreated controls, was ≥97% to 100% against adult Dictyocaulus filaria, Haemonchus contortus, Teladorsagia circumcincta(pinnata/trifurcata), Trichostrongylus axei, T.colubriformis, Cooperia curticei, Nematodirus battus, and Oesophagostomum venulosum. Both pharmacokinetic parameters and anthelmintic activity in lactating dairy goats were similar to those observed in parasitized young growing and adult female non-lactating dairy goats treated with eprinomectin administered as a pour-on.

Descriptive analysis of nematode management practices and Nematodirus battus control strategies on UK sheep farms.

Farm management practices have a major impact on nematode population dynamics. The presented study aimed to understand current nematode management practices on UK sheep farms; with a particular focus on Nematodirus battus because of the changing epidemiology, and emerging anthelmintic resistance observed in this species. A 42 question online survey covering grazing management, farm demographics and parasite control strategies was developed and distributed to the farming community in 2016. Analysis of the 187 completed questionnaires explored regional variations in practices. Uptake of recommendations was variable, particularly quarantine practices and monitoring tools. Results also highlighted variation in the epidemiology of N. battus; respondents in the north (Scotland, north-west and north-east England) typically reported N. battus in spring with a perception of more severe clinical symptoms than those from the south (Midlands, Wales, south-east and south-west England; p=0.03). Farms in the south observed greater changes in the timing of disease (p=0.006) with N. battus being reported throughout the year on some holdings and more frequent use of faecal egg count monitoring (p=0.006). Control of N. battus infection is challenging and 'one-size-fits-all' advice is not applicable; however, the information gathered will enable the development of effective, adaptable control strategies.

The identification and semi-quantitative assessment of gastrointestinal nematodes in faecal samples using multiplex real-time PCR assays

BackgroundThe diagnosis of gastrointestinal nematode (GIN) infections in ruminants is routinely based on morphological/morphometric analysis of parasite specimens recovered by coprological methods, followed by larval culture (LC) techniques. Such an approach is laborious, time-consuming, requires a skilled expert, and moreover suffers from certain limitations. Molecular tools are able to overcome the majority of these issues, providing accurate identification of nematode species and, therefore, may be valuable in sustainable parasite control strategies.MethodsTwo multiplex real-time polymerase chain reaction (PCR) assays for specific detection of five main and one invasive GIN species, including an internal amplification control to avoid false-negative results, were designed targeting SSU rRNA and COI genetic markers, as well as established ITS1/2 sequences. The assays were optimized for analysis of DNA extracted directly from sheep faeces and verified for Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis, Nematodirus battus, Chabertia ovina, and Ashworthius sidemi. Semi-quantitative evaluation of infection intensity was enabled using a plasmid construct and a dilution series of sheep faeces with a known number of nematode eggs. Assays were tested on 44 individually collected faecal samples from three farms, and results were compared to those from faecal egg counts (FEC) using the concentration McMaster technique and LC.ResultsMultiplex real-time PCR assays showed great specificity to target nematodes. During the analysis of faecal samples, the assays proved to have higher sensitivity in strongylid-type egg detection over FEC by revealing three false-negative samples, while showing moderate agreement in evaluation of infection intensity. The multiplex assays further clarified GIN species identification compared to LC, which had confused determination of Teladorsagia spp. for Trichostrongylus spp.ConclusionsOur multiplex assays proved to be a rapid and accurate approach enabling simultaneous and reliable GIN species identification from faeces and semi-quantitative estimation of the number of eggs present. This approach increases diagnostic value and may add a high degree of precision to evaluation of anthelmintic efficacy, where it is important to identify species surviving after treatment.Graphical

Comparing two predictive risk models for nematodirosis in Great Britain

Nematodirus battus infection is a major health concern in lambs. Development and hatch of infective larvae on pastures is temperature dependent, making model-based risk forecasting a useful tool for disease control. Air and 30 cm soil temperature-based risk models were used to predict hatch dates using meteorological data from 2019 and compared to infection dates, estimated from the first appearance of N. battus eggs, on 18 sheep farms distributed across Great Britain. The air temperature model was more accurate in its predictions than the soil temperature model on 12 of the 18 farms, but tended to predict late hatch dates in the early part of the season. Overall, the air temperature model appears the more appropriate choice for predicting N. battus peak hatch in the UK in terms of accuracy and practicality, but some adjustment might be needed to account for microclimatic variations at the soil-air interface.

Variation in hatching responses of Nematodirus battus eggs to temperature experiences

BackgroundNematodirus battus, unlike most other gastrointestinal nematodes, undergoes maturation to an infective larva within the egg. Historically, eggs were considered to require a period of chilling over winter followed by a period of temperature above 10 °C for synchronous hatching to occur (generally in spring). Anecdotal reports of Nematodirus infection out-with spring in veterinary journals and the farming press suggest that the concentrated pasture abundance of N. battus infective larvae may be changing. In order for control practices to be adapted, and unexpected disease outbreaks to be avoided, it is important to quantify how parasite epidemiology is changing and research the drivers behind it.MethodThe present study investigated the in vitro hatching response to temperature experiences (with and without a period of chilling) for egg samples of 90 N. battus populations obtained from 73 commercial sheep farms. Six aliquots of larvated eggs were prepared per population, three aliquots were placed at 4 °C for 6 weeks to provide a chill stimulus then incubated at the optimal hatching temperature for the species. The remaining three aliquots of eggs were incubated at the hatching temperature without a prior chill stimulus and the number of hatched larvae was compared between treatments.ResultsMedian hatch rate across all populations with chilling was 45% (95% CI: 42–48%) and without chilling was 4% (95% CI: 2–6%). Inter-population variation in hatching ranged from 0 to 87% of eggs able to hatch in the absence of a chill stimulus, mean non-chill hatching was 13 ± 2% of eggs (mean ± SE). Non-chill hatching rates were greater than chilled hatching rates in seven of the 90 populations tested.ConclusionsClearly, the variation in hatching responses to temperature experience is very large and therefore the seasonality of the parasite may vary not only between regions but also at farm level. In contrast to what previous work has suggested, there was a geographical trend towards higher non-chill hatching in the Northern parts of the UK.

Large scale screening for benzimidazole resistance mutations in Nematodirus battus, using both pyrosequence genotyping and deep amplicon sequencing, indicates the early emergence of resistance on UK sheep farms

Benzimidazoles (BZ) have been the anthelmintic of choice for controlling Nematodirus battus infections since their release in the 1950s. Despite heavy reliance on this single anthelmintic drug class, resistance was not identified in this nematode until 2010 (Mitchell et al., 2011). The study aimed to explore the prevalence of BZ-resistance mutations in N. battus from UK sheep flocks using deep amplicon sequencing and pyrosequencing platforms. Based on evidence from other gastrointestinal nematodes, resistance in N. battus is likely to be conferred by single nucleotide polymorphisms (SNP) within the β-tubulin isotype 1 locus at codons 167, 198 and 200. Pyrosequencing and deep amplicon sequencing assays were designed to identify the F167Y (TTC to TAC), E198A (GAA to GCA) and F200Y (TTC to TAC) SNPs. Nematodirus battus populations from 253 independent farms were analysed by pyrosequencing; 174 farm populations were included in deep amplicon sequencing and 170 were analysed using both technologies. F200Y was the most prevalent SNP identified throughout the UK, in 12–27% of the populations tested depending on assay, at a low overall individual frequency of 2.2 ± 0.6% (mean ± SEM, based on pyrosequencing results). Four out of the five populations with high frequencies (>20%) of the F200Y mutation were located in NW England. The F167Y SNP was identified, for the first time in this species, in four of the populations tested at a low frequency (1.2% ± 0.01), indicating the early emergence of the mutation. E198A or E198L were not identified in any of the isolates. Results obtained were comparable between both techniques for F200Y (Lins’ CCC, rc = 0.96) with discrepancies being limited to populations with low frequencies. The recent emergence of resistance in this species will provide a unique opportunity to study the early stages of anthelmintic resistance within a natural setting and track its progress in the future.

Planning anthelmintic treatments to control gastrointestinal nematode infections in sheep

A planned approach to anthelmintic treatments against gastrointestinal nematodes in sheep is vital given their clinical and economic importance, and the prevalence of anthelmintic resistance. The key nematode species in the UK are Nematodirus battus, Teladorsagia circumcincta, Trichostrongylus species and Haemonchus contortus. Knowledge of the biology of these species and the annual production cycle on UK sheep farms can guide when treatments may be necessary. The timings of these treatments can be further refined using grazing history, weather conditions and faecal egg counting. This information can then be combined with knowledge of anthelmintic resistance to make a rational treatment decision, and reduce the selection for anthelmintic resistance; for example, by using strategies that maintain populations of parasites in refugia, using multiple active treatments or improving drug bioavailability.

Eprinomectin pour-on: Prevention of gastrointestinal and pulmonary nematode infections in sheep

The present study was conducted to further characterize the anthelmintic activity of the 0.5% w/v topical formulation of eprinomectin (EPRINEX® Pour-on, Merial) when administered at 1 mg/kg body weight to sheep in preventing the establishment of induced gastrointestinal and pulmonary nematode infections.Thirty-six female Merino sheep (∼4 months of age, weighing 27.0–36.0 kg) were blocked by pre-treatment body weight to form blocks of four animals. Within blocks, the animals were randomly allocated to either remain untreated (control) or be treated once with EPRINEX® either on Day 0, Day 7 or Day 14. Starting on Day 15, the sheep were given trickle infections with infective larvae of seven species of gastrointestinal nematodes and Dictyocaulus filaria lungworms daily for seven consecutive days. Five weeks after completion of the daily challenge (Day 56), the animals were necropsied for parasite recovery and count.Treatment with EPRINEX® prevented the establishment (>90%, p ≤ 0.027) of D. filaria, Teladorsagia circumcincta (pinnata/trifurcata), Cooperia curticei, Nematodirus battus, Trichostrongylus colubriformis and Oesophagostomum venulosum for at least 21 days, and of Haemonchus contortus and Trichostrongylus axei for at least 14 days. Sheep in the groups treated with EPRINEX® at Days 7 and 14 had significantly (p ≤ 0.018) higher Day -1 to Day 56 wt gains than the untreated controls.No treatment-related health problems or any other health problems were observed throughout the study.

Helminths parasites of digestive trackt of sheep and goats in Macedonian region

During two periods (December 1985-October 1986 and October 1990-April 1991), the digestive tracts of 102 sheep and 29 goats were examined, with the purpose to find out and identify the helminthes parasites of these animals. The 96,1% of sheep and 93,1% of goats were found to be infected with 26 and 20 different helminths, respectively. The nematodes which were found out of the different parts of the digestive tract of these animals were: Sheep: oesophagus: Gongylonema pulchrum, abomasum: Haemonchus contortus, Teladorsagia circumcincta, T. trifurcata, Trichostrongylus axei and Cooperia oncophora, small intestine: Teladorsagia circumcincta, Trichostrongylus colubriformis} T. vitrinus, T. capricola, Cooperia oncophora, C. curticei, Nematodirus filicollis, N. helvetianus, N. spathiger, N. battus, Bunostomum trigonocephalum and Strongyloides papillosus, large intestine: Oesophagostomum venulosum, Oe. columbianum, Chabertia ovina, Trichuris globulosa, T. ovis and Skrjabinema ovis. Goats: all the previous findings except T. vitrinus, Nematodirus helvetianus, N. battus and Trichuris ovis. The cestodes parasites, Moniezia expansa, Moniezia benedni, Avitellina centripunctata and Stilesia globipunctata were found into the small intestine of sheep and, Moniezia expansa and Avitellina centripunctata, in goats only. All animals were infected with more than one different parasites. The sheep nematodes Cooperia curticei, Nematodirus helvetianus, and N. spathiger, were identified for the first time in Greece, more over, Nematodirus battus were found out and identified for the first time in Greece.

An investigation into the effects of maternal supplementation with excess iodine on the mechanisms and impacts of reduced IgG absorption in the lamb postpartum.

An experiment was conducted to determine: (1) the effect of excess maternal I supplementation on the thyroid hormone status of the ewe and her progeny; (2) potential mechanisms underpinning the failure of passive transfer associated with excess I and (3) the growing lambs' response to natural gastrointestinal infection. Twin-bearing ewes received one of two treatments (n 32/treatment group): basal diet (C) or C plus 26·6 mg of iodine/ewe per d (I), supplied as calcium iodate. Ewes were individually fed from day 119 of gestation to parturition. Progeny of I ewes had lower (P<0·01) serum IgG concentrations from 24 h to 28 d postpartum but higher serum IgG concentrations at day 70 postpartum (P<0·05). I supplementation increased the relative expression of Fc receptor, IgA, IgM high affinity and polymeric Ig receptor in the ileum of the lamb at 24 h postpartum; however, thyroid hormone receptor-β (THRB) and β-2-microglobulin (B2M) expression declined (P<0·05). Progeny of I ewes had higher growth rates to weaning (P<0·05) and lower faecal egg count (FEC) for Nematodirus battus (P<0·05) between weeks 6 and 10 postpartum. In conclusion, excess maternal I supplementation negatively affected the thyroid hormone status, serum IgG concentration, ileal morphology and the gene expression of THRB and B2M in the ileum and ras-related protein (RAB) RAB25 and the mucin gene (MUC) MUC1 in the duodenum of the lamb postpartum. These effects were followed by an enhancement of average daily gain and lower N. battus FEC in the pre-weaning period of I-supplemented lambs.

Perceptions and actions of Dutch sheep farmers concerning worm infections

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<0.001). Both ewes and lambs were frequently treated based on fixed moments such as around lambing, at weaning and before mating, rather than based on faecal egg counts. Treatments based on faecal egg counts were practiced, but on a minority of the farms (32.7%). The majority of the farms (75.6%) did not leave 2–5% of the sheep within a flock untreated. About 74% of farmers keep newly purchased animals quarantined for at least 10days, but some (13.4%) leave quarantined animals untreated nor check faecal egg counts. Of farmers who do treat their quarantined animals, just 12.6% check the efficacy of the treatment.Slightly over 40% of the respondents said they did not experience bottlenecks in parasite control. Yet, over half of these said having problems with worm infections, over half did see clinical signs related to worm infections and over three quarters used anthelmintics. Within the group of farmers experiencing difficulties in parasite control, the most often mentioned bottleneck concerned pasture management (75.8%). When asking farmers for solutions, 90% of all respondents indicated they are willing to adjust their pasture management. Farmers are also interested in other methods to reduce the risk of worm infections, such as possibilities to enhance the immune system of sheep in general (71%), to increase specific genetic resistance to worms and to apply anti-parasite forages, both about 40%.Results of this study gave the following potential foci of attention: (1) making complex scientific knowledge more accessible to farmers through simple tools and applicable in the daily farming process; (2) changing the mindset of farmers about their current worm control practices, i.e. breaking long-standing habits such as treating ewes and lambs at fixed moments rather than based on actual worm infection monitoring data; (3) demonstrating effective pasture rotation schemes on specific farms and using these in extension work; (4) making farmers more aware that checking anthelmintic efficacy is important; (5) improving quarantine procedures; (6) creating a wider array of applicable alternative control measures from which individual farmers can choose what fits them most; and finally, (7) improving mutual understanding among farmers, veterinary practitioners and parasitologists alike.

Asynchrony in host and parasite phenology may decrease disease risk in livestock under climate warming: Nematodirus battus in lambs as a case study.

Mismatch in the phenology of trophically linked species as a result of climate warming has been shown to have far-reaching effects on animal communities, but implications for disease have so far received limited attention. This paper presents evidence suggestive of phenological asynchrony in a host-parasite system arising from climate change, with impacts on transmission. Diagnostic laboratory data on outbreaks of infection with the pathogenic nematode Nematodirus battus in sheep flocks in the UK were used to validate region-specific models of the effect of spring temperature on parasite transmission. The hatching of parasite eggs to produce infective larvae is driven by temperature, while the availability of susceptible hosts depends on lambing date, which is relatively insensitive to inter-annual variation in spring temperature. In southern areas and in warmer years, earlier emergence of infective larvae in spring was predicted, with decline through mortality before peak availability of susceptible lambs. Data confirmed model predictions, with fewer outbreaks recorded in those years and regions. Overlap between larval peaks and lamb availability was not reduced in northern areas, which experienced no decreases in the number of reported outbreaks. Results suggest that phenological asynchrony arising from climate warming may affect parasite transmission, with non-linear but predictable impacts on disease burden. Improved understanding of complex responses of host-parasite systems to climate change can contribute to effective adaptation of parasite control strategies.

Anthelmintic efficacy and pharmacokinetics of pour-on eprinomectin (1 mg/kg bodyweight) against gastrointestinal and pulmonary nematode infections in goats

Two controlled studies were performed to assess the efficacy and pharmacokinetics of topical 0.5% w/v eprinomectin (EPRINEX® Pour-on, Merial) against nematode infections of goats. Each study included 16 male castrated goats, less than one year old, harboring induced infections of adult gastrointestinal and pulmonary nematodes. Following blocking on pre-treatment bodyweight and random allocation to one of two groups, half the goats in each study were treated once with eprinomectin (1mg/kg bodyweight, administered topically), and half remained untreated and served as controls. Plasma concentrations of eprinomectin were determined in blood samples collected prior to and at multiple time points up to necropsy. Efficacy was determined based on the nematode counts of the animals following necropsy 14 days after treatment.Efficacy of treatment was 100% against adult Haemonchus contortus, Nematodirus battus, Nematodirus spathiger, Oesophagostomum venulosum, Teladorsagia circumcincta and Dictyocaulus filaria was >94% against adult Cooperia curticei, Trichostrongylus axei and Trichostrongylus colubriformis, and was 89.4% against adult Strongyloides papillosus (p<0.01). Basic pharmacokinetic parameters of eprinomectin (B1a component) for the goats in the two studies were: AUClast, 23.5±5.19/36.0±8.74 day*ng/mL; and Cmax, 3.65±1.12/5.25±1.39ng/mL, respectively; individual maximum plasma concentrations were observed 1 or 2 days after treatment. Results of the studies consistently demonstrated a high therapeutic efficacy of topical eprinomectin at 1mg/kg bodyweight against a broad range of gastrointestinal and pulmonary nematode parasites of goats.