Calicophoron daubneyi (Paramphistomidae) in deer of the Sumava National Park, Czech Republic - Consequence of prevalent rumen fluke infection in cattle.

A substantial parallel increase in prevalence and geographical spread of the rumen fluke, Calicophoron daubneyi, in livestock in western and central Europe has been recognized in the recent past. In the course of the examination of rectum feces of 471 red deer (Cervus elaphus) and one sika deer (Cervus nippon) from the Fascioloides magna endemic Sumava National Park in the years 2021 and 2022, rumen fluke eggs were detected in four red deer (0.8%) and the sika deer and identified as eggs of C. daubneyi by molecular analysis. Subsequent examination of rectal fecal samples of 247 beef cattle from 22 herds of 14 farms located in or nearby the national park revealed rumen fluke eggs in 53 samples (21.5%) originating from 16 herds of 11 farms, molecularly identified as C. daubneyi eggs as well. One C. daubneyi egg positive red deer and three C. daubneyi egg positive cattle samples also contained fasciolid eggs, respectively, which were detected in 9.5% or 3.6% of the total samples from red deer or cattle, respectively. Results of this investigation reveal the first finding of C. daubneyi in sika deer worldwide and in red deer in mainland Europe and add to the growing number of reports on C. daubneyi in livestock in Europe. Considering that the ratio of cattle excreting rumen fluke eggs exceeded that of deer substantially, it can reasonably be assumed that the C. daubneyi infections in deer are a consequence of the prevalent infection in cattle, illustrating a pathogen spillover event from livestock into wildlife.

Phytochemical analysis and anthelmintic activity of Combretum mucronatum leaf extract against infective larvae of soil-transmitted helminths including ruminant gastrointestinal nematodes.

BACKGROUND: Soil-transmitted helminths (STH) infect more than a quarter of the world's human population. In the absence of vaccines for most animal and human gastrointestinal nematodes (GIN), treatment of infections primarily relies on anthelmintic drugs, while resistance is a growing threat. Therefore, there is a need to find alternatives to current anthelmintic drugs, especially those with novel modes of action. The present work aimed to study the composition and anthelmintic activity of Combretum mucronatum leaf extract (CMLE) by phytochemical analysis and larval migration inhibition assays, respectively. METHODS: Combretum mucronatum leaves were defatted with petroleum ether and the residue was extracted by ethanol/water (1/1) followed by freeze-drying. The proanthocyanidins and flavonoids were characterized by thin layer chromatography (TLC) and ultra-high performance liquid chromatography (UPLC). To evaluate the inhibitory activity of this extract, larval migration assays with STH and GIN were performed. For this purpose, infective larvae of the helminths were, if necessary, exsheathed (Ancylostoma caninum, GIN) and incubated with different concentrations of CMLE. RESULTS: CMLE was found to be rich in flavonoids and proanthocyanidins; catechin and epicatechin were therefore quantified for standardization of the extract. Data indicate that CMLE had a significant effect on larval migration. The effect was dose-dependent and higher concentrations (1000 µg/mL) exerted significantly higher larvicidal effect (P < 0.001) compared with the negative control (1% dimethyl sulfoxide, DMSO) and lower concentrations (≤ 100 µg/ml). Infective larvae of Ascaris suum [half-maximal inhibitory concentration (IC50) = 5.5 µg/mL], Trichuris suis (IC50 = 7.4 µg/mL), and A. caninum (IC50 = 18.9 µg/mL) were more sensitive to CMLE than that of Toxocara canis (IC50 = 310.0 µg/mL), while infective larvae of Toxocara cati were largely unaffected (IC50 > 1000 µg/mL). Likewise, CMLE was active against most infective larvae of soil-transmitted ruminant GIN, except for Cooperia punctata. Trichostrongylus colubriformis was most sensitive to CMLE (IC50 = 2.1 µg/mL) followed by Cooperia oncophora (IC50 = 27.6 µg/mL), Ostertagia ostertagi (IC50 = 48.5 µg/mL), Trichostrongylus axei (IC50 = 54.7 µg/mL), Haemonchus contortus (IC50 = 145.6 µg/mL), and Cooperia curticei (IC50 = 156.6 µg/mL). CONCLUSIONS: These results indicate that CMLE exhibits promising anthelmintic properties against infective larvae of a large variety of soil-transmitted nematodes.

Efficacy of eprinomectin 5 mg/mL topical solution administered pour on at 1 mg per kg body weight against Oestrus ovis myiasis in sheep and goats.

The larvae of the nasal bot, Oestrus ovis, mainly parasitize sheep and goats and some species of wild Caprinae but other mammals and humans are also vulnerable to infestation. Eprinomectin 5 mg/mL topical solution (EPRINEX® Multi, Boehringer Ingelheim) administered at 1 mg eprinomectin per kg body weight pour on was recently authorized as an anthelmintic for sheep and goats with zero hours milk withdrawal in several countries in Europe. As the product in cattle has claims against a broad range of parasites including insect parasites and activity against O. ovis has previously been reported following extra-label use in sheep, its therapeutic efficacy against ovine and caprine O. ovis myiasis was evaluated in three regulatory compliant, masked clinical studies. Pre-study recovery of O. ovis larvae from five or six of six randomly selected animals per study site (Bulgaria, one site, sheep; Greece, two sites, sheep or goats) supported the inclusion of the animals from those sites into the studies. The study animals (34 animals per study) were ranked based on bodyweight and allocated randomly to remain untreated (control) or to be treated with eprinomectin 5 mg/mL topical solution at 1 mL per 5 kg body weight pour on. Treatment efficacy was determined based on O. ovis larval counts of eprinomectin 5 mg/mL topical solution-treated vs. untreated animals three weeks after treatment administration. Live O. ovis larvae, including all three instars in each study, were recovered from 13 or 16 of the 17 control animals in the sheep studies (range, 1 to 14 or 5 to 18 larvae, respectively) and from all 17 controls in the goat study (range, 7 to 18 larvae). In each study, eprinomectin 5 mg/mL topical solution-treated animals had significantly (p < 0.001) fewer live O. ovis larvae than the controls. Efficacy of the treatment was 100% and 91.3% against the combined parasitic O. ovis larval stages in sheep and in goats, respectively. The treatment was well accepted by all animals and no health problems were observed throughout the studies. The results of these studies demonstrated eprinomectin 5 mg/mL topical solution administered pour on at 1 mL per 5 kg body weight to be an efficacious and safe treatment of ovine and caprine oestrosis.

Protostrongylus caprae Zdzitowiecki et Boev, 1971 (Nematoda: Protostrongylidae) - First record in Alpine ibex (Capra ibex Linnaeus, 1758) from Europe.

In the course of a survey of the endoparasites of Alpine ibex (Capra ibex) from Austria, examination of the lungs revealed male Protostrongylus nematodes presenting morphological characters which differed from those of the three Protostrongylus species previously reported from this host. Fragments of 16 adult male and 4 adult female nematodes extracted from the lung tissue of two female ibex following peptic digestion were subjected to close microscopic examination. Based on their morphology, the lungworms were identified as Protostrongylus caprae Zdzitowiecki et Boev, 1971. This species was originally described from Siberian ibex (Capra sibirica) in Asia and previously only reported from this host from Kazakhstan and Mongolia. The identification of P. caprae in Alpine ibex represents a new host and geographical record and reinforces the interest to further study the parasite diversity of wild ungulates for a better understanding of complex host-parasite associations and biogeography.

Plasma pharmacokinetics of clorsulon following administration of a single subcutaneous or intravenous injection to cattle.

The benzenedisulfonamide derivative clorsulon is a potent fasciolicide which is marketed in fixed combination injectables, typically combined with the macrocyclic lactone ivermectin. In the presented pharmacokinetic study, the plasma profile of clorsulon in 32 healthy, young Brown Swiss cattle was administered a single intravenous dose at 3 mg/kg body weight or subcutaneously at 3, 6 or 12 mg/kg body weight (4 intact male and 4 female animals per treatment) as a 30% w/v clorsulon injection formulation. Serial blood samples were collected up to 24 days after administration to establish the pharmacokinetics, bioavailability and dose proportionality of clorsulon. Following a single intravenous injection of clorsulon at 3 mg/kg body weight, the area under the concentration versus time curve from the start of dose administration to the time of the last quantifiable concentration (AUClast ) was 4830 ± 941 day*ng/mL, and half-live was 2.37 ± 0.98 days. The back extrapolated concentration at time 0 was 38,500 ± 6070 ng/mL. The volume of distribution at steady state and clearance were 685 ± 107 mL/kg and 664 ± 127 mL/day/kg, respectively. In the groups dosed at 3, 6 or 12 mg/kg body weight by subcutaneous injection, clorsulon plasma concentrations rose to maximum within 0.5 day and decreased to the last sample point. For these groups, the maximum plasma clorsulon concentrations were 3100 ± 838, 5250 ± 1220 and 10,800 ± 1730 ng/mL, respectively, and the AUClast was 5330 ± 925, 9630 ± 1300 and 21,500 ± 3320 day*ng/mL, respectively. Half-lives, 2.01 ± 0.62, 3.84 ± 1.42 and 5.36 ± 0.60 days, respectively, increased significantly with dose, likely related to increasing dose volume. Clorsulon was well absorbed and fully bioavailable (103%-114%) after subcutaneous injection. No gender-related difference in systemic exposure was observed. Assessment of Cmax and AUClast demonstrated a proportional increase in systemic exposure to the clorsulon subcutaneous doses over the range of 3-12 mg/kg body weight.

Host-pathogen associations revealed by genotyping of European strains of Anaplasma phagocytophilum to describe natural endemic cycles.

BACKGROUND: The zoonotic intracellular alpha-proteobacterium Anaplasma phagocytophilum is a tick-transmitted pathogen. The associations between vertebrate reservoirs and vectors are described as wide-ranging, and it was previously shown that the pathogenicity of A. phagocytophilum differs depending on the combination of pathogen variant and infected host species. This leads to the question of whether there are variations in particular gene loci associated with different virulence. Therefore, this study aims at clarifying existing host-variant combinations and detecting possible reservoir hosts. To understand these interactions, a complex toolset for molecular epidemiology, phylogeny and network theory was applied. METHODS: Sequences of up to four gene loci (msp4, msp2, groEL and 16S rRNA) were evaluated for different isolates from variable host species, including, for example, dogs, cattle and deer. Variant typing was conducted for each gene locus individually, and combinations of different gene loci were analysed to gain more detailed information about the genetic plasticity of A. phagocytophilum. Results were displayed as minimum spanning nets and correlation nets. RESULTS: The highest diversity of variants for all gene loci was observed in roe deer. In cattle, a reduced number of variants for 16S rRNA [only 16S-20(W) and 16S-22(Y)] but multiple variants of msp4 and groEL were found. For dogs, two msp4 variants [m4-20 and m4-2(B/C)] were found to be linked to different variants of the other three gene loci, creating two main combinations of gene loci variants. Cattle are placed centrally in the minimum spanning net analyses, indicating a crucial role in the transmission cycles by possibly bridging the vector-wildlife cycle to infections of humans and domestic animals. The minimum spanning nets confirmed previously described epidemiological cycles of the bacterium in Europe, showing separation of variants originating from wildlife animals only and a set of variants shared by wild and domestic animals. CONCLUSIONS: In this comprehensive study of 1280 sequences, we found a high number of gene variants only occurring in specific hosts. Additionally, different hosts show unique but also shared variant combinations. The use of our four gene loci expand the knowledge of host-pathogen interactions and may be a starting point to predict future spread and infection risks of A. phagocytophilum in Europe.

Molecular pathogen screening of louse flies (Diptera: Hippoboscidae) from domestic and wild ruminants in Austria.

BACKGROUND: Hippoboscid flies (Diptera: Hippoboscidae), also known as louse flies or keds, are obligate blood-sucking ectoparasites of animals, and accidentally of humans. The potential role of hippoboscids as vectors of human and veterinary pathogens is being increasingly investigated, but the presence and distribution of infectious agents in louse flies is still unknown in parts of Europe. Here, we report the use of molecular genetics to detect and characterize vector-borne pathogens in hippoboscid flies infesting domestic and wild animals in Austria. METHODS: Louse flies were collected from naturally infested cattle (n = 25), sheep (n = 3), and red deer (n = 12) across Austria between 2015 and 2019. Individual insects were morphologically identified to species level and subjected to DNA extraction for molecular pathogen screening and barcoding. Genomic DNA from each louse fly was screened for Borrelia spp., Bartonella spp., Trypanosomatida, Anaplasmataceae, Filarioidea and Piroplasmida. Obtained sequences of Trypanosomatida and Bartonella spp. were further characterized by phylogenetic and haplotype networking analyses. RESULTS: A total of 282 hippoboscid flies corresponding to three species were identified: Hippobosca equina (n = 62) collected from cattle, Melophagus ovinus (n = 100) from sheep and Lipoptena cervi (n = 120) from red deer (Cervus elaphus). Molecular screening revealed pathogen DNA in 54.3% of hippoboscids, including infections with single (63.39%), two (30.71%) and up to three (5.90%) distinct pathogens in the same individual. Bartonella DNA was detected in 36.9% of the louse flies. Lipoptena cervi were infected with 10 distinct and previously unreported Bartonella sp. haplotypes, some closely associated with strains of zoonotic potential. DNA of trypanosomatids was identified in 34% of hippoboscids, including the first description of Trypanosoma sp. in H. equina. Anaplasmataceae DNA (Wolbachia spp.) was detected only in M. ovinus (16%), while < 1% of the louse flies were positive for Borrelia spp. and Filarioidea. All hippoboscids were negative for Piroplasmida. CONCLUSIONS: Molecular genetic screening confirmed the presence of several pathogens in hippoboscids infesting domestic and wild ruminants in Austria, including novel pathogen haplotypes of zoonotic potential (e.g. Bartonella spp.) and the first report of Trypanosoma sp. in H. equina, suggesting a potential role of this louse fly as vector of animal trypanosomatids. Experimental transmission studies and expanded monitoring of hippoboscid flies and hippoboscid-associated pathogens are warranted to clarify the competence of these ectoparasites as vectors of infectious agents in a One-Health context.

Multispecies helminth parasitism of grazing dairy cows in Germany and Austria, examined in the housing period.

Helminth composition and burden data for dairy cows have not been reported for >40 years for Germany and even less information is available for Austria. In the context of two recent studies, helminth parasitism was studied in 32 cows (23 from six farms in Bavaria and Tyrol; 9 from one farm in Saxony) from pasture-based dairy farms necropsied during the housing period. Helminths were enumerated and identified based on morphological characters (all helminths but rumen flukes) or molecular techniques (rumen flukes). Thirteen species of gastrointestinal nematodes and two species each of liver flukes (Fasciola hepatica, Dicrocoelium dendriticum) and rumen flukes (Calicophoron daubneyi, Paramphistomum leydeni) were recorded; no lungworms were recovered from any cow. Early fourth-stage (inhibited) larval Ostertagia species nematodes (210 to 140,600) were recovered from all cows, 31 each had adult Ostertagia ostertagi/Ostertagia lyrata (40 to 2020) and Trichostrongylus axei (10 to 53,400), 23 Oesophagostomum radiatum (1 to 242) and 20 Cooperia punctata (10 to 3330). Other nematodes present in descending order of prevalence were: Cooperia oncophora/Cooperia surnabada, Ostertagia leptospicularis/Ostertagia kolchida, Oesophagostomum venulosum, Bunostomum phlebotomum, Chabertia ovina, Nematodirus helvetianus, Trichostrongylus longispicularis, Haemonchus contortus and Aonchotheca bilobata. The cows from Bavaria and Tyrol harbored more total gastrointestinal nematodes than that from Saxony (geometric mean adult plus inhibited larval nematodes, 6510 vs. 2051, respectively). However, in both cohorts of cows abomasal nematodes accounted for ∼97% of the total nematode burden with inhibited larval Ostertagia species nematodes contributing over 70% of the total gastrointestinal nematode burden and âˆ¼ 96% of the Ostertagia species burden. Approximately 44%, 37% and 19% of the cows harbored <5000, 5000 to 10,000 or > 10,000 total gastrointestinal nematodes, respectively. Fecal nematode egg and coproculture nematode larval counts significantly correlated with the cows' total adult nematode burden (rs = 0.354, p < 0.05, and rs = 0.608, p < 0.001, respectively). Although the magnitude of nematode burden to exert production effects on dairy cows is not well defined and may vary relative to several factors including nutritional supplementation, the level of mixed parasitism found in this investigation supports consideration of grazing dairy cows in helminth control measures, especially at the time of housing in autumn.

Molecular identification of Sarcocystis species in sika deer (Cervus nippon) of free-ranging populations in Germany and Austria.

In this study, for the first time, Sarcocystis species were identified molecularly in sika deer (Cervus nippon) that form free-ranging populations in several countries of Europe. Diaphragm muscle samples from 151 deer from 10 populations in Germany and Austria were examined for sarcocysts. By one-gram methylene-blue staining, sarcocysts were recorded in samples of 114 animals (75.5%) which originated from all populations. Sarcocysts were more often (p < 0.0001) recorded in yearling and adult deer than in calves. Infection intensity was generally low with ~ 70% of the sarcocyst positive deer harbouring ≤ 10 sarcocysts per 1-gram diaphragm muscle. Based on cox1 sequence comparison, 10 species of Sarcocystis, all previously reported parasitizing cervids, were identified: S. elongata, S. entzerothi, S. hjorti, S. iberica, S. japonica, S. linearis, S. morae, S. pilosa, S. silva and S. truncata. The prevailing S. hjorti was detected in sika deer of all 10 populations. The identification in sika deer of S. hjorti, S. iberica, S. elongata, S. linearis, S. morae and S. silva constitutes new host records. With the additional species records of this study, the highest number of Sarcocystis species, at least 16, was identified in this host.

Efficacy of eprinomectin topical solution and eprinomectin extended-release injection treatments against developing larval and adult Chabertia ovina and Oesophagostomum venulosum - two less common cattle nematode parasites.

The efficacy of the topical and injection formulations of eprinomectin (0.5 % w/v topical solution, EPRINEX®; 5 % w/v extended-release injection, LONGRANGE®; Boehringer Ingelheim) against larval and adult stages of the rare bovine large intestine nematodes Chabertia ovina and Oesophagostomum venulosum was evaluated in one Good Clinical Practice study compliant to World Association for the Advancement of Veterinary Parasitology and International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products anthelmintic guidelines. Forty nematode naïve induced infected Brown Swiss calves were allocated into five groups of eight completely at random. Inoculation with isolates obtained in Germany was staggered so that the parasites of the two species were, when the treatments were administered, concurrently fourth-stage larval or adult nematodes, respectively. One group served as untreated control, two groups each received eprinomectin 0.5 % w/v topical solution or eprinomectin 5 % w/v extended-release injection per product label. Animals were necropsied at one and the same day (corresponding to six weeks or two weeks after administration of treatments against fourth-stage larval or adult nematodes) for parasite recovery and count. Both C. ovina (range, 39-604) and O. venulosum (range, 3-23) were recovered from all eight controls while among the 32 calves which were administered topical solution or extended-release injection eprinomectin, only a single C. ovina specimen was isolated from one animal which received the injection product when the nematodes were adult. Eprinomectin treatments were > 99.9 % effective against fourth-stage larval or adult C. ovina and O. venulosum nematodes (p 0.001 at α = 0.05). All animals accepted the treatments well. No adverse events or other health problems were observed in the study animals.

Morphological and ontogenetic characteristics of Miridex putorii (Acariformes: Demodecidae), a new genus and species of skin mite specific to the European polecat Mustela putorius.

Among carnivorans, mites of the family Demodecidae are mainly represented by the eight species of the genus Demodex known to cause demodecosis in domestic dog Canis lupus familiaris Linnaeus, 1758 and domestic cat Felis catus Linnaeus, 1758. However, nine other Demodex species from wild carnivorans are also known; in addition they are only known from few records. Previously unknown demodecid mites have been isolated from European polecats, Mustela putorius Linnaeus, 1758, originating from Germany. The specimens are characterized of by an aedeagus with a posterior end located between the opisthosoma and podosoma and an anterior end in the gnathosoma area, with a genital opening in the epistome area; aedeagus length corresponds to 53% (45-59%) of male body length. The mites were isolated from the head skin in 16 of 21 polecats examined (76.2%), mainly in the mystacial vibrissae area (84.8%) and less often in adjacent areas. However, the mite infestation did not appear to cause skin abnormality. Based on the morphological analysis of the adult mites and their morphological ontogenesis, including significant characteristics in demodecid taxonomy, the mite specimens have been classified as representatives of a new species and genus, described as Miridex putorii gen. nov., sp. nov.

Reflections and future directions for continued development and refinement of guidelines for anthelmintic efficacy studies.

This reflection paper complements the WAAVP (World Association for the Advancement of Veterinary Parasitology) general anthelmintic efficacy guideline, which outlines the general principles of anthelmintic efficacy evaluation across all animal host species. It provides background to the recommendations made in the WAAVP general anthelmintic efficacy guideline, with insights into the discussions leading to specific recommendations in the general guideline or the absence thereof. Furthermore, this paper discusses recent technological advancements with potential value to the evaluation of anthelmintic efficacy that may be considered for future versions of the general or species-specific guidelines if supported by sufficient levels of evidence. Finally, it also identifies potential research questions, such as the statistical approach for comparing worm counts between groups of animals.

Eprinomectin 5% w/v extended-release injection for the treatment of larval and/or adult Bunostomum phlebotomum, Haemonchus contortus, H. placei, Nematodirus helvetianus, Oesophagostomum radiatum, and Trichostrongylus colubriformis infections in cattle.

In an effort to generate data for regulatory purposes on the therapeutic efficacy of eprinomectin 5% w/v extended-release injection (Eprinomectin ERI) (LongRange®, Boehringer Ingelheim) against infections of immature and adult stages of some nematode species (or stages) which are generally less common or predominantly seen in younger cattle, nine studies (minimum two per parasite and stage) were conducted in the USA and Germany. A total of 218 young cattle were included in seven experimentally induced infection studies (180 animals) and two studies with naturally acquired nematode infections (38 animals), which were compliant with WAAVP and VICH guidelines. In each study, cattle were randomly assigned into groups which received 1 mL per 50 kg body weight of either saline (controls) or Eprinomectin ERI (equivalent to 1 mg eprinomectin per kg body weight) via subcutaneous injection when the parasites were developing fourth-stage larval (L4) or adult nematodes. Following necropsy and parasite recovery, percentage efficacy was calculated based on the comparison of geometric mean nematode counts of the Eprinomectin ERI- vs. the saline-treated animals. Eprinomectin ERI-treated cattle had significantly (p < 0.05) lower counts of each species and stage of nematodes than the controls. Eprinomectin ERI treatment was demonstrated to be efficacious (> 90%) against L4 and adult Bunostomum phlebotomum and Nematodirus helvetianus; against L4 Haemonchus placei, Oesophagostomum radiatum, and Trichostrongylus colubriformis; and against adult H. contortus. Percentage efficacy against L4 H. contortus was variable (69.6 to 100%). All treatments were well accepted, and no treatment-related health problems were observed in any study.

Distribution, prevalence, and intensity of Sarcocystis infections in sika deer (Cervus nippon) of free-ranging populations in Germany and Austria.

Sika deer (Cervus nippon), which are native to the Japanese islands and the adjacent mainland of eastern Asia, have been introduced into Europe and established free-ranging populations in several countries. Various Sarcocystis species have been identified recently from farmed "mainland sika" deer in Lithuania and native "Japanese sika" deer in Japan. To study the distribution, prevalence and intensity of Sarcocystis infection in free-ranging sika deer outside of their natural range heart and/or diaphragm samples of 311 animals from nine populations in Germany and Austria were examined by histology.Overall, sarcocysts were detected in either heart or diaphragm of 107/311 deer (34.4%) with prevalence ranging roughly from 5 to 50% among the populations. Considering the 263 animals with both heart and diaphragm available, prevalence varied significantly (p < 0.0001) among calves (20.2%), yearlings (40.3%), and adult deer (49.1%) but did not differ between male and female deer (48.3% vs. 43.7%; p = 0.6483). Occurrence of sarcocysts in heart vs. diaphragm indicated a marginal difference (27.8% vs. 20.9%; p = 0.0839). Intensity of infection in all but one heart positive and all diaphragm positive animals was low (< 10 sarcocysts per square centimeter muscle cut). While heart sarcocyst counts of yearlings and adult deer were higher than those of calves and were higher in male compared to female sika deer, diaphragm sarcocyst counts did not differ significantly between age groups and sexes. Sarcocystis infection was demonstrated at variable prevalence in sika deer in all populations but intensity is apparently low. Further studies are needed to identify the species of Sarcocystis infecting sika deer naturalized outside their natural range.

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 1 mL/50 kg body weight once subcutaneously), treated and euthanized 14 days 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.

A note on the relationship between fecal larval excretion and Protostrongylus rufescens lungworm burden in sheep.

The examination of feces for stages of parasitic helminths is the most widely used methodology for the intravital diagnosis in domestic animals of patent endoparasitism including pulmonary nematode infections. Although there is only little information on the relationship of lungworm larval excretion and corresponding parasite burdens, fecal larval counts are used as indirect measure ("biomarker") for the intensity of infection, for instance in anthelmintic efficacy studies. To assess the relationship between fecal larval and Protostrongylus rufescens parasite counts in sheep, log-transformed data of 14 naturally infected animals were analyzed. The larval excretion of the sheep was monitored in approximately weekly intervals over 6 weeks before lungworm recovery. Analyses were performed on the larval counts (at a single time point or counts averaged over several consecutive time points) relating to parasite counts. Fecal larval counts and the P. rufescens nematode burden (range, 17 to 406) were significantly and strongly correlated (p < 0.05 for all analyses; Spearman's r > 0.6) with the number of larvae excreted increasing with increasing lungworm burden. Subsequently performed regression analysis demonstrated a statistically significant strong linear relationship between P. rufescens worm and fecal larval counts (p < 0.01 for all analyses; R2, range 0.5094 to 0.8150). Analyses based on larval counts averaged over two or more consecutive time points resulted in higher Spearman's r and R2 compared with analyses based on single time point larval counts. Despite of some variability, the analyses indicate that fecal larval counts can be regarded as a useful measure of the P. rufescens burden in sheep.

Pharmacokinetic-pharmacodynamic relationships of pour-on administered eprinomectin in nematode-infected lactating female and male castrated dairy breed goats.

Eprinomectin (EPM), a macrocyclic lactone with low excretion in milk and high efficacy against endoparasites and ectoparasites, is widely used in veterinary medicine. In this paper, EPM pharmacokinetics and anthelmintic efficacy previously established in one study with lactating female goats and three studies with male castrated growing dairy breed goats (all with induced mixed adult gastrointestinal nematode parasitism and treated with a single 1-mg/kg pour-on administration of EPM) were retrospectively evaluated using pharmacokinetic-pharmacodynamic (PK-PD) modeling. The PK-PD analyses between EPM exposure (Cmax and AUClast) and anthelmintic response (percent efficacy) were performed for lactating female goats only and pooled lactating female and male castrated goats. The Cmax and AUClast showed no significant difference between lactating female goats and combined male castrated goats. PK-PD modeling demonstrated Trichostrongylus colubriformis, a small-intestine nematode, as a suitable indicator of the EPM nematocidal efficacy. The EC90 values obtained by modeling Cmax vs T. colubriformis were 3.50 and 2.43 ng/mL for lactating female goats only and pooled lactating female and male castrated goats, respectively. The values of AUClast needed for 90% efficacy of T. colubriformis were 25.4 and 21.1 day*ng/mL for lactating female goats only and pooled lactating female and male castrated goats, respectively. Overall, the predicted pharmacological response against T. colubriformis is similar for lactating goats only and pooled lactating female and male castrated goats and correlates with observed efficacy. In conclusion, a dosage of 1-mg/kg EPM as a pour-on is sufficient to ensure efficacy against common nematodes in both lactating female and male castrated goats.

World association for the advancement of veterinary parasitology (WAAVP): Third edition of guideline for evaluating the efficacy of equine anthelmintics.

This guideline have been developed to assist in the design, execution, and interpretation of studies to assess the efficacy of anthelmintic drugs against internal parasites of equines, including nematodes, cestodes, and larval instars of Gasterophilus spp. The design and execution of critical and controlled studies are outlined, and their advantages and disadvantages are discussed. Unique considerations for specific target parasites are included. Information is also provided on selection of animals, procedures for randomization, housing, feeding, dosage titration, dosage confirmation and field studies, record keeping and necropsy procedures. Finally, this document includes guidance for group size determination and statistical analysis of study results. This guideline should assist investigators in the evaluation of anthelmintic drugs in horses by using comparable and standardized procedures in studies with appropriate numbers of animals.

World Association for the Advancement of Veterinary Parasitology (WAAVP) second edition: Guideline for evaluating the efficacy of parasiticides against ectoparasites of ruminants.

This second edition guideline was prepared to assist in the planning, conduct and interpretation of studies to assess the efficacy of parasiticides against ectoparasites of ruminants. It provides updated information on the selection of animals, dosage determination, dosage confirmation and field studies, record keeping and result interpretation. This guideline is intended to assist investigators on how to conduct specific studies, to provide specific information for registration authorities involved in the decision-making process, to assist in the approval and registration of new ectoparasiticides, and to facilitate the worldwide adoption of standard procedures.

Treatment of natural Protostrongylus rufescens lungworm infection in sheep with eprinomectin 5 mg/mL topical solution.

Parasitic respiratory infections in domestic sheep and goats are caused by Dictyocaulus filaria and various species belonging to the Protostrongylidae family of nematodes which frequently occur in mixed infections. Although the parasitism with protostrongylid lungworms is generally considered to be of low pathogenicity, there are reports of clinical disease including cases associated with Protostrongylus rufescens infection. The efficacy against P. rufescens of eprinomectin 5 mg/mL topical solution (EPRINEX® Multi, Boehringer Ingelheim) was thus evaluated in a clinical study compliant with GCP and VICH anthelmintic efficacy testing guidelines in adult sheep with naturally acquired infection. Following ranking on pre-treatment Protostrongylus fecal larval counts and forming into blocks of two animals, the sheep were randomly allocated to either remain untreated (control) or to be administered eprinomectin 5 mg/mL topical solution at 1 mL/5 kg body weight (equivalent to 1 mg eprinomectin per kg body weight) once as a pour-on. Fecal samples of the sheep were examined to monitor the larval excretion weekly for five weeks after treatment; then the animals were necropsied for lungworm recovery and count to determine the efficacy of the treatment. After treatment, Protostrongylus larval excretion decreased to zero within three weeks. Nematode counts demonstrated that the efficacy of the treatment with eprinomectin 5 mg/mL topical solution was 100 % against P. rufescens: no lungworms were recovered from any treated sheep while all controls harbored P. rufescens (range, 17-406) (p < 0.001). The treatment was well accepted; no treatment-related health problems were observed.