World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) methods for the detection of anthelmintic resistance in nematodes of veterinary importance

Gastrointestinal nematode parasites of grazing ruminants: a comprehensive literature review of diagnostic methods for quantifying parasitism, larval differentiation and measuring anthelmintic resistance

This review summarises up-to-date research on the diagnosis of gastrointestinal nematode (GIN) infection in livestock and anthelmintic resistance in GIN. It was commissioned to assist funding bodies to prioritise and guide research and extension efforts to improve the health, welfare and productivity of grazing ruminants in the face of challenge with GIN. A comprehensive review of published articles from journals, books and websites was undertaken, with a focus on peer-reviewed articles published between 2000 and 2024 involving genera of GIN in grazing sheep and cattle with economic importance to New Zealand. Suggestions for articles to include were received from 14 experts in GIN diagnostics. This review is a summary of a longer report submitted to the sponsoring organisation. Clinical signs of GIN infection in grazing ruminants in temperate grazing systems are inadequate as triggers for management interventions including anthelmintic treatment as they are visible only after economically significant pathological changes have occurred. Livestock producers benefit from monitoring GIN burdens using faecal egg counts (FEC) or associated signals such as weight gain. In future, they may use remote monitoring devices for activity in animals, as well as estimating pasture larval contamination. Methods of diagnosing GIN infections using automated FEC devices have improved the convenience of monitoring parasite burdens compared with traditional laboratory methods. However, a lack of quality control measures and a gap in training of skilled technicians for larval differentiation may lead to a shortage of diagnostic capability. Current methods of diagnosing anthelmintic resistance, particularly FEC reduction tests, are not likely to be replaced by laboratory assays in the near future and attention should be focused on facilitating application of new FEC technologies for both animal monitoring and resistance diagnosis. Extension and application of currently available methods and technology will improve animal health and productivity in ruminant grazing systems in the short term. Adoption of novel technologies for remote animal monitoring, practical tools for estimating pasture larval contamination and promoting genetic selection for immunity and resilience to GIN in both sheep and cattle will further enhance productivity in the long term.

Emergence of dual drug-resistant strongylids in goats: first phenotypic and genotypic evidence from Ratchaburi Province, central Thailand

BACKGROUND

This study provides crucial insights into the prevalence and drug resistance patterns of strongylid gastrointestinal nematodes (GINs) in goats in Thailand, highlighting resistance to albendazole and levamisole. Strongylids, particularly Haemonchus sp. and Trichostrongylus sp., pose a significant threat to goat health. With the global rise of anthelmintic resistance, the detection of multidrug resistance in Thailand's goat population is concerning, given the frequent import and export of goats. This resistance challenges effective parasite control strategies. This study aimed to identify strongylid species using both morphological and genetic methods and to assess resistance to albendazole and levamisole through phenotypic and molecular approaches.

RESULTS

Fecal samples from 30 goat farms in Ratchaburi Province revealed a high prevalence of strongylid infection (87%), with Haemonchus sp. and Trichostrongylus sp. detected on 100% and 96% of farms, respectively. Phenotypic assays demonstrated significant drug resistance, with 90% and 71% of farms harboring strongylid populations resistant to albendazole and levamisole, respectively. Genotypic analysis of pooled infective larvae showed that 100% of farms had albendazole-resistant strongylid populations, with 31% homozygous and 69% heterozygous resistance, and Trichostrongylus sp. showing 48% homozygous and 52% heterozygous resistance. For levamisole resistance, 92% of farms contained resistant strongylid populations, with Haemonchus sp. exhibiting 11% homozygous and 81% heterozygous resistance.

CONCLUSIONS

This study provides the first comprehensive evaluation of phenotypic and genotypic resistance in strongylid nematodes in Ratchaburi Province, addressing a key geographical gap in Thailand's resistance data. The findings highlight the urgent need to reassess GIN management practices and develop sustainable strategies to mitigate resistance. Furthermore, these results have significant implications for transboundary livestock health, emphasizing the necessity of collaborative efforts to combat the growing challenge to anthelmintic drugs.

Occurrence of Internal Parasites and Anthelmintic Resistance in Goats

Extensive anthelmintic (AH) use for endoparasitism prevention, especially gastrointestinal strongyle (GIS) infections, led to AH resistance (AR). This study assessed the internal parasitic profile and AR occurrence in goat herds. Five herds (H, n = 300) raised in household systems in Romania (2020-2021) were dewormed with eprinomectin in the fall (H1, H2) and albendazole in the spring (H3-H5). Fecal samples (n = 67) were collected pre- and 14 days post-AH administration. Coprological examinations, coprocultures, and polymerase chain reaction (PCR) were performed. Anthelmintic resistance was detected in H1, H2, and H5. Pre-AH administrations, Eimeria spp. was the most common parasite (95.5%), followed by GIS (91.0%), P. rufescens/M. capillaris (77.6%), Dyctiocaulus filaria (56.7%), and Moniezia spp. (43.3%). Teladorsagia circumcincta (4/5), Trichostrongylus colubriformis (4/5), Oesophagostomum venulosum (3/5), Haemonchus placei (3/5), Haemonchus contortus (2/5), and Cooperia oncophora (2/5) were identified by PCR. Mean OPG/EPG values for Eimeria spp. and GIS were <1000 eggs/gram feces, tending to be higher in young versus adult goats and in autumn versus spring. FECR (90%CI) values post-AH administration were 38.42 (23.4; 71.8), 54.71 (-4.1; 75.1) for eprinomectin, and 9.78 (-1.7; 64.8) for albendazole, suggesting AH ineffectiveness and AR presence in H1, H2, and H5, respectively. These findings highlight that specific management measures are needed.

Efficacy of fenbendazole against gastrointestinal nematodes in naturally infected goats in Maputo Province, Mozambique using in vivo, in vitro and molecular assessment

Anthelmintic resistance occurs worldwide in strongyles of ruminants but data from low-income countries are sparse and rarely apply most up to date methods, while effects of management practices in these countries are poorly documented. In Mozambique, benzimidazole resistance has been previously reported; the present study followed this up in detail, applying in vivo faecal egg count (FEC) reduction test (FECRT), in vitro egg hatch test (EHT) and molecular deep amplicon sequencing approaches targeting the internal transcribed spacer 2 (ITS-2, nemabiome) and the isotype 1 β-tubulin gene to determine the resistance status on farms and the strongyle species involved. Adult Landim goats (433) from six semi-intensive and ten extensive farms (22-30 animals/farm) from Maputo Province were visited April 2021 to February 2022. Fenbendazole (5 mg/kg bw, Panacur®) was administered orally and FEC determined using Mini-FLOTAC. The eggCounts package was used to calculate FECRs with 90% confidence intervals from paired day 0 and 14 data. In vivo and in vitro tests detected AR on 5/16 (31%) farms. This included 1/10 extensive and 4/6 semi-intensive farms. The odds of finding resistant strongyles on a semi-intensive commercial farm was 40-fold higher than on an extensive farm (p = 0.016, logistic regression). A strong, negative correlation was observed between FECRT and EHT EC50 values (Pearson's R = -0.83, P = 0.001; Cohen's κ coefficient 1.0). Nemabiome data showed that Haemonchus contortus, Trichostrongylus colubriformis and unclassified Oesophagostomum closely related to Oesophagostomum columbianum were most abundant before treatment and in particular H. contortus frequencies increased after treatment. Benzimidazole resistance associated polymorphisms were detected in H. contortus and T. colubriformis. Moreover, there were hints that resistance alleles were present in Trichostrongylus axei and Teladorsagia circumcincta. Farmers should regularly test the efficacy of anthelmintics used and consider more sustainable worm control approaches to reduce selection for resistance.

Biotransformation of anthelmintics in nematodes in relation to drug resistance

In all organisms, the biotransformation of xenobiotics to less toxic and more hydrophilic compounds represents an effective defense strategy. In pathogens, the biotransformation of drugs (used for their elimination from the host) may provide undesirable protective effects that could potentially compromise the drug's efficacy. Accordingly, increased drug deactivation via accelerated biotransformation is now considered as one of the mechanisms of drug resistance. The present study summarizes the current knowledge regarding the biotransformation of anthelmintics, specifically drugs used to treat mainly nematodes, a group of parasites that are a significant health concern for humans and animals. The main biotransformation enzymes are introduced and their roles in anthelmintics metabolism in nematodes are discussed with a particular focus on their potential participation in drug resistance. Similarly, the inducibility of biotransformation enzymes with sublethal doses of anthelmintics is presented in view of its potential contribution to drug resistance development. In the conclusion, the main tasks awaiting scientists in this area are outlined.

Anthelmintic activity on Haemonchus contortus and toxicity of benzoyl-carvacrol: a study in vitro, in silico and in vivo

Carvacrol is isolated from essential oils and possesses activity against gastrointestinal nematodes of small ruminants. Benzoylation has been proposed to improve its pharmacological and pharmacokinetic properties. The objectives of this study were to evaluate the ovicidal activity of benzoyl-carvacrol (BC) against Haemonchus contortus, the in silico interaction of BC with the β-tubulin protein and the toxicity of this compound. Carvacrol was subjected to benzoylation and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). The activity of BC and carvacrol was evaluated against H. contortus in the egg hatching test. The in silico study was based on molecular docking with the β-tubulin and thiabendazole used as control. The acute toxicity test was performed with BC and carvacrol by up-and-down procedure (limit test: 2,000 mg/kg) in Wistar rats. GC/MS confirmed the benzoylation. BC and carvacrol inhibited egg hatching by 99.70 and 98.89% at concentrations of 3.16 and 1 mg/mL, respectively, and interacted with β-tubulin. No mortality was caused by compounds, but rats treated with carvacrol demonstrated intoxication signs. These findings indicated that BC showed effect on H. contortus and can potentially interact with β-tubulin of nematodes in addition to presenting toxicological safety in laboratory animals.

Insights into the role of bioactive plants for lambs infected with Haemonchus contortus parasite

Bioactive plants provide therapeutic and prophylactic effects to ruminants. We determined the effect of grazing on natural meadow grassland enriched with experimentally sown chicory (Cichorium intybus) on parasitological status, pasture larval infectivity, antioxidant parameters, and the histology of abomasal tissue in lambs experimentally infected with the parasitic gastrointestinal nematode (GIN) Haemonchus contortus. We also qualitatively identified the main polyphenols in the meadow grassland and phenolic metabolites in the feces of the lambs. Sixteen lambs were orally infected with approximately 5,000 infective larvae (L3) of H. contortus. The lambs were divided into two groups: lambs grazing on a plot consisting exclusively of meadow pasture which serves as control group and lambs grazing on a plot where approximately 25% of a meadow grassland was reclaimed with chicory. The experimental period was 144 days. The number of eggs per gram (EPG) of feces was quantified on D21, D34, D48, D62, D76, D89, D103, D118, D131, and D144 post-infection. Pasture contamination with H. contortus L3 was examined. EPG in both groups of lambs was highest at D34. Egg shedding was significantly lower in both groups from D48 onwards, with a reduction of >95% from D103 onwards. Pasture contamination with L3 was highest at D41 but was then significantly lower in both groups. The total antioxidant capacity, the activity of glutathione peroxidase and the concentration of malondialdehyde in the serum changed significantly during the experiment (p < 0.003, < 0.001, and < 0.016, respectively). At least 54 species of meadow plants were identified on both pasture plots; plant bioactive compounds identified were mainly phenolic acids, flavonoids, and glucosides. Phenolic metabolites (e.g., coumaric acid, chicory acid, salvigenin, and esters of gallic acid) were identified in the feces of the lambs. In some lambs, the morphological observation identified small histopathological changes in the abomasal tissues typical of hemonchosis. Both the natural meadow pasture and the pasture enriched with experimentally sown chicory slowed the dynamics of GIN infection and pasture contamination with L3 by mobilizing the antioxidant defensive system and gradually increasing the resistance of the infected lambs, probably due to the beneficial effects of plant bioactive substances.

Inhibitory effect of dimethyl sulfoxide on the development of gastrointestinal nematode larvae in the larval development test

Introduction

Dimethyl sulfoxide (DMSO) is an amphipathic solvent for molecules in in vitro tests for detection of anthelmintic resistance of gastrointestinal nematodes (GIN). It has been shown to have a concentration-dependent detrimental effect on Caenorhabditis elegans, a free-living nematode. If GIN are likewise affected, using DMSO in egg-hatch test and larval development test (LDT) may confound their results. Therefore, the DMSO concentration was determined at which it exerted an inhibitory effect on GIN larval development to the third stage.

Material and Methods

A standard LDT was performed in 30 replications at DMSO concentrations of 0.0% (control), 0.6%, 1.3%, 2.6%, 5.2%, 10.4%, and 20.8%. The numbers of all developmental stages of Haemonchus contortus, Trichostrongylus spp. and Oesophagostomum spp. (unhatched eggs, larvae of the first, second and third stages (L1-L3) were determined, the proportion of L3 (the percentage of larval development - PD) was calculated and L3 were identified at the species or genus level. A five-parameter logistic curve was fitted to the observed PDs and modelled the DMSO-larval development relationship.

Results

The PD significantly decreased with increasing DMSO concentration and was significantly reduced at the 2.6% concentration. The median inhibitory concentration (IC50) was 3.79%, the concentration for 10% inhibition (IC10) was 1.75% and for 90% inhibition (IC90) was 8.20%. The percentage of L1 and L2 followed an analogical but opposite pattern to that of PD and was complementary to it at each DMSO concentration. The unhatched egg percentage was rarely >1% and showed no pattern.

Conclusion

At ≥2.6% concentration, DMSO significantly inhibited the L3 development of all three GIN species. It had a practically important inhibitory effect (IC10) at as low concentration as 1.75%. At lower concentrations, DMSO did not appear to inhibit larval development. The compound did not seem to exert an in vitro ovicidal effect regardless of the concentration.

Albendazole resistance evidence in Teladorsagia circumcincta in Iranian sheep by allele-specific PCR

Gastrointestinal nematodes (GIN) have a considerable impact on the livestock husbandry and health conditions in Iran as well as worldwide. The infected animals with GIN mostly need chemical therapy which leads to the development of anthelmintic drug resistance. The main objective of the current study was to determine the frequency of β-tubulin isotype 1 gene polymorphism to albendazole (Alb) in Teladorsagia circumcincta isolated from sheep abomasum in Urmia city, Iran. A total number of 140 sheep abomasa were randomly collected and 57(40.7%) were infected with T. circumcincta (157 adult T. circumcincta per sheep). Alb resistance in T. circumcincta determined using Allele-Specific PCR (ASP) technique. Molecularly, the frequency of resistant alleles to Alb in examined T. circumcincta was 48.3%, i.e. 51.7% homozygous susceptible (SS), 6.9% homozygous resistant (rr) and 41.4% heterozygous susceptible (Sr). It was concluded that Alb-resistance alleles were increasingly widespread in examined T. circumcincta, therefore prevention and control program should be lunched in the region.

Epidemiology of caprine gastrointestinal nematodes and associated efficacy of anthelmintic drugs in Punjab districts, India

Gastrointestinal parasites pose a serious threat to sustainable small ruminant farming worldwide including Indian subcontinent and the control primarily relies on administration of anthelmintic drugs. A continuous surveillance regarding their distribution and efficacy of commonly used anthelmintics is essential for their effective control in a region. In the present study, faecal samples (n = 1962) were collected from goats of 17 districts of Punjab state, India and examined by qualitative and quantitative examination methodologies. An overall prevalence of 93.62% was recorded for gastrointestinal parasitism with strongyles being the most prevalent (88.99%), followed by coccidia (65.34%), Moniezia spp. (16.62%), Trichuris spp. (9.38%), Strongyloides spp. (7.65%) and trematodes (Fasciola spp. and amphistomes) being least prevalent (0.02%). The quantitative analysis revealed 48.05, 14.43 and 37.51% goats with low, moderate and heavy gastrointestinal nematode infection (GIN), respectively, while faecal culture examination revealed six genera of GINs as Haemonchus (75.94%) being the predominant, followed by Trichostrongylus (16.44%), Oesophagostomum (4.85%), Bunostomum (1.65%), Ostertagia (0.77%) and Cooperia (0.33%). The logistic regression analysis revealed that risk factors viz. agroclimatic zones, season, sex and deworming status were significantly associated with prevalence of gastrointestinal parasites. The status of efficacy against fenbendazole, levamisole and ivermectin were also analysed by in-vivo faecal egg count reduction test at 17 goat farms. The overall percent efficacy as mean ± SE (range) for fenbendazole, levamisole and ivermectin was estimated at 55.97 ± 4.78% (18.92-92.44%), 51.74 ± 4.77% (11.20-77.86%) and 62.63 ± 4.66% (32.41-98.63%), respectively. The results revealed resistance against fenbendazole, levamisole and ivermectin on 100%, 100% and 94.1% farms, respectively, whereas, in-vitro tests (egg hatch test and larval developmental assay) revealed resistance as 70.6%, 93.8% and 73.3%, respectively. The high prevalence of GINs in Punjab state can be correlated with the resistance recorded against all commonly used anthelmintics and warrants exploration of non-chemical mitigation strategies for effective control. The findings of the present study would be of immense help for the policy-framers/field veterinarians/extension worker etc. in formulation and implementation of effective control measures for worm management through judicious use of the anthelmintics.

Chromosomal genome assembly resolves drug resistance loci in the parasitic nematode Teladorsagia circumcincta

The parasitic nematode Teladorsagia circumcincta is one of the most important pathogens of sheep and goats in temperate climates worldwide and can rapidly evolve resistance to drugs used to control it. To understand the genetics of drug resistance, we have generated a highly contiguous genome assembly for the UK T. circumcincta isolate, MTci2. Assembly using PacBio long-reads and Hi-C long-molecule scaffolding together with manual curation resulted in a 573 Mb assembly (N50 = 84 Mb, total scaffolds = 1,286) with five autosomal and one sex-linked chromosomal-scale scaffolds consistent with its karyotype. The genome resource was further improved via annotation of 22,948 genes, with manual curation of over 3,200 of these, resulting in a robust and near complete resource (96.3% complete protein BUSCOs) to support basic and applied research on this important veterinary pathogen. Genome-wide analyses of drug resistance, combining evidence from three distinct experiments, identified selection around known candidate genes for benzimidazole, levamisole and ivermectin resistance, as well as novel regions associated with ivermectin and moxidectin resistance. These insights into contemporary and historic genetic selection further emphasise the importance of contiguous genome assemblies in interpreting genome-wide genetic variation associated with drug resistance and identifying key loci to prioritise in developing diagnostic markers of anthelmintic resistance to support parasite control.

Assessing the benzimidazole resistance in equine strongyles by in vitro methods

The study aimed to conduct a survey on the occurrence of benzimidazole (BZ) resistance in strongyles by in vitro egg hatch test (EHT) and larval development test (LDT) and to identify the effective indicators of early resistance detection on horse farms with associated risk factors analysis appraisal. In total, 203 horses from 8 farms underwent the fecal sampling of which 77 horses were selected for in vitro testing. Simultaneously, 18 horses were chosen to analyse the results of in vitro tests compared to the in vivo fecal egg count reduction test (FECRT). The EHT indicated the presence of resistant strongyles in all farms with an exceeded threshold of 0.1 μg/ml thiabendazole (TBZ) in 43 horses (55.84 %). The percent egg hatch at 0.1 μg/ml TBZ in "resistant parasites" varies from 39.0 ± 6.0 % to 91.0 ± 1.0 %. The hatching range between 8.5 ± 1.5 % and 50.0 ± 6.0 % at a concentration of 0.1 μg/ml TBZ was detected wherein the recommended threshold was not exceeded. The analysis of the EHT results demonstrated that egg hatching at the 0.1 µg/ml TBZ concentration was identified as the most important predictor of the early detection of BZ resistance. In the LDT, the mean TBZ concentration which interrupted the development of 50 % and 99 % larvae to the infective stage (L3) from all horses was 0.0753 ± 0.0454 and 0.6798 ± 1.9144 μg/ml TBZ, respectively. Only cyathostomin L3 were found at TBZ concentrations ≥ 0.08 μg/ml and only in samples from 81.8 % of horses (36/44). A comparison of LDT results did not show a statistically significant agreement with EHT and FECRT. In conclusion, the in vitro EHT could be implemented as an indicator for early BZ resistance detection and showed that monitoring of hatching at selected concentrations could detect presence and estimate the proportion of the resistant parasite population on the horse farms.

C, Marques MJ, Correia Ribeiro WL. Simarouba berteroana Krug & Urb. Extracts and Fractions Possess Anthelmintic Activity Against Eggs and Larvae of Multidrug-Resistant Haemonchus contortus

Gastrointestinal nematode infections significantly impact small ruminant production, causing substantial economic losses worldwide. The rising resistance to anthelmintics has led to the search for alternative treatments, including phytotherapeutic approaches. This study investigates the chemical composition and anthelmintic activity of crude extracts and fractions from Simarouba berteroana, an endemic plant from Hispaniola, against a multidrug-resistant isolate of Haemonchus contortus. Chemical analyses revealed high contents of phenolic compounds, tannins, and flavonoids and confirmed the presence of 22 quassinoids, 5 phytosterol lipids, 3 terpenoid quinones, 3 alkaloids, and 1 naphthoquinone. The hydroalcoholic and iso-butanol fractions showed the strongest egg hatching inhibition (IC50 = 0.93 and 1.21 mg/mL, respectively), while hexane fractions were less effective (p < 0.05). Fluorescence microscopy showed that the extracts and fractions adhered to eggshells, causing evisceration and cuticle detachment in hatched larvae. All extracts, except for hexane fractions, inhibited larval exsheathment at 0.3 mg/mL, with phenolic compounds being responsible for this effect. These results provide the first evidence of the ovicidal and larval exsheathment inhibition activities of S. berteroana extracts and fractions against H. contortus, highlighting their potential in managing gastrointestinal nematodes in small ruminants. Further in vivo studies are needed to confirm these findings.

Gastrointestinal parasitic worm burdens and efficacy of deworming practices in growing beef cattle grazing California pastures

Treatment for enteric parasites is a common practice in beef cattle, yet little data is known about the prevalence of nematode and trematode parasite infections in beef cattle in the western United States. Likewise, the data on the efficacy of deworming practices and the presence of anthelmintic resistance (AR) of these parasites in this region is sparse. The current study collected evidence for the presence of nematode and trematode parasites in 18 herds of young beef cattle grazing either dryland or irrigated pasture in northern California as well as on efficacy and evidence of AR in a subgroup of herds. We found variable levels of fecal egg counts (FEC) ranging from 6 to 322 for the arithmetic mean eggs per gram (EPG) in the tested cattle groups. There was no difference in the number of EPG between herds grazing dryland or irrigated pasture (P = 0.54). We did not find any evidence for liver flukes or lungworms in the tested cattle. There was evidence of AR to macrocyclic lactones in all eight herds where fecal egg count reduction tests (FECRT) were performed, however due to types and execution of treatment applications and sample sizes, these results need to be interpreted with caution. The most common genus of third stage larvae in coproculture testing before treatment was Cooperia (between 55% and 98% of larvae) as well as post treatment for those herds undergoing FECRT (between 50% and 96%). Ostertagia was the second most frequent genus of larvae found in coproculture testing making up between 0% and 27% of larvae before treatment and between 5% and 50% of larvae after treatment. Anthelmintic practices in beef herds in northern California and likely in a larger geographic area in the western United States need to be updated in order to continue effective use of the currently available drugs.

In vitro evaluation of anthelmintic activity of biocompatibile carbon quantum dot nanocomposite against egg and larval stages of equine strongyles

BACKGROUND

Strongyle nematodes pose a major challenge in veterinary parasitology, causing significant economic losses in livestock due to resistance to conventional treatments. Current anthelmintics, like Ivermectin, often encounter resistance issues. This study aims to address these gaps by synthesizing Carbon Quantum Dots (CQDs) and Copper-Doped CQDs (Cu@CQDs) using glucose extract, and evaluating their nematicidal properties against strongyles in vitro. We assessed the nematicidal effects of CQDs and Cu@CQDs through larval feeding inhibition of first-stage larvae (L1), egg hatch inhibition (EHI), and the mobility and mortality of infectious larvae (L3s). Additionally, we conducted ultrastructural examinations of eggs and larvae and evaluated oxidative/nitrosative stress indicators, including total antioxidant status (TAS), protein carbonylation (PCO), lipid peroxidation (MDA), and oxidative DNA damage in homogenized samples of L3s.

RESULTS

The synthesized CQDs displayed semi-spherical morphology with diameters under 30 nm. Cu@CQDs at 12.5 µg/ml achieved over 90% EHI and larval motility inhibition. Fluorescence microscopy confirmed over 90% larval feeding inhibition at the same concentration. Both CQDs and Cu@CQDs induced oxidative stress, indicated by decreased TAS and increased MDA, PCO, and oxidative DNA damage. Scanning Electron Microscopy showed that CQDs and Cu@CQDs penetrated the larvae cuticle, altered the tegument, caused larval mortality, and resulted in egg deformities.

CONCLUSIONS

Given the potential for resistance to Ivermectin, seeking suitable alternatives is essential. Cu@CQDs exhibit effects similar to Ivermectin, indicating their potential as novel antiparasitic agents against strongyles. These findings emphasize the importance of exploring alternative treatments to address resistance and enhance nematode control efficacy.

The Anthelmintic Activity of Nepeta racemosa Lam. Against Gastrointestinal Nematodes of Sheep: Rosmarinic Acid Quantification and In Silico Tubulin-Binding Studies

Gastrointestinal nematodes (GINs) inflict significant economic losses on sheep and goat farming globally due to reduced productivity and the development of anthelmintic resistance. Sustainable control strategies are urgently needed including the exploration of medicinal plants as safer alternatives to chemical anthelmintics. This genus of plants is used for anti-inflammatory, antioxidant, and antimicrobial activities. In this study, we aimed to evaluate the anthelmintic activities of Nepeta racemosa Lam. MeOH extract, n-hexane, dichloromethane (DCM), ethyl acetate (EtOAc), n-buthanol (n-BuOH) and aqueous (H2O) subextracts, and quantify rosmarinic acid in the active extract by the HPLC method, and perform in silico molecular docking studies of rosmarinic acid to examine its binding interactions with tubulin. The anthelmintic activity of the plant extracts on gastrointestinal nematode eggs and larvae (L3) of the sheep was assessed using in vitro test methods such as the egg hatch assay and larval motility assay, conducted over a 24 h period (1, 2, 3, 4, 6, 8, 24). All extracts exhibited 100% effectiveness in the egg hatch inhibition assay, regardless of concentration (50-1.5625 mg/mL). The EtOAc subextract shows the highest effectiveness at 79.66%, followed by the MeOH extract at 74.00%, water at 64.00%, n-hexane at 67.00%, and DCM at 61.00%, and the lowest effectiveness is observed with n-BuOH at 51.66% in the larval motility assay. The major compound of EtOAc extract, the most active extract of N. racemosa, was determined as rosmarinic acid and its amount in the extract was determined as 14.50 mg/100 mg dry extract. The amount of rosmarinic acid in the MeOH extract was found to be 0.21 mg/100 mg dry extract. n-Hexane, DCM, n-BuOH, and H2O extracts' rosmarinic acid content was lower than the LOQ value. As tubulin plays an important role in the mechanism of anthelmintics, the major compound of the most active extract (NR-EtOAc) rosmarinic acid was docked onto the colchicine-binding site of the tubulin (5OV7) protein. Rosmarinic acid showed a similar activity spectrum to the anthelmintic drug albendazole. The discovery of low-cost and low-toxicity anthelmintic compounds is very important.

First report of anthelmintic resistance among sheep in six farms from three governorates in Jordan

This study aimed to identify the presence of gastrointestinal nematode populations resistant to albendazole, levamisole, and ivermectin in six farms located in three regions of Jordan (Irbid, Mafraq, and Ma'an). Infected sheep (40 per farm) with at least 100 eggs per gram were randomly divided into four groups (10 animals per group). Three groups were treated with ivermectin, albendazole, or levamisole while the fourth group was used as a negative control group. The standard faecal egg count reduction test (FECRT) was used to assess the drugs' efficacy. Resistance to ivermectin and albendazole was detected in all studied farms while resistance to levamisole was detected in four of the sampled farms. FECRT ranged from 55.6 % (90 % Confidence Intervals (CI): 29.6 % - 79.6 %) to 80.3 % (CI: 48.3 % - 92.1 %) for ivermectin, 77.4 % (CI: 53.2-86.7 %) to 95 % (CI: 85.8-97.6 %) for albendazole, and 86 % (CI: 46.1-95.6 %) to 99.4 % (CI: 97.6-99.7 %) for levamisole. Post-treatment copro-cultures, faecal floatation and/or Baermann technique indicated the presence of larvae of Haemonchus spp. in all of the sampled farms, followed by Nematodirus spp. in four farms, Trichostrongylus spp. in three farms, then Marshallagia spp. in one farm. This is the first study of its kind in Jordan that shows widespread anthelmintic resistance for gastrointestinal nematodes in geographically distant sheep farms in Jordan. Such widespread resistance to anthelmintics imposes a risk of failure to the present control programs and urges for changing the methodology of selecting effective anthelmintic treatments in local farms.

In vivo anthelmintic activity of hydroethanolic extract of Piper cubeba fruits in sheep naturally infected with gastrointestinal nematodes

Parasitic infections caused by gastrointestinal nematodes (GINs) are the main cause of production losses in small ruminants, especially sheep. Haemonchus contortus is the most common nematode in tropical regions. The indiscriminate use of synthetic anthelmintics to control helminthosis has led to the development of resistant parasites. As a result, there has been growing interest in using plant extracts and natural products to control gastrointestinal nematodes in sheep. Therefore, this study aimed to evaluate the in vivo anthelmintic activity of the hydroethanolic extract of Piper cubeba fruit in sheep naturally infected with gastrointestinal nematodes. Initially, an experiment was conducted where the Piper cubeba extract was administered at a dose of 2.5 mg/kg body weight three times at 7-day intervals. For this, 18 animals were divided into three groups: a control group, a group treated with levamisole phosphate at 4.7 mg/kg body weight subcutaneously, and a group treated with Piper cubeba extract, which was administered in pure form orally to the animals through a cannula. Based on the results of this experiment, a second experiment was conducted using the same experimental design and same extract, but the effectiveness of the extract was evaluated at a single dose of 5.0 mg/kg body weight administered on day 0. The determination of biochemical parameters for the group treated with extract and the identification of nematode species for all groups were performed on different days of this experiment. The results of the first experiment showed that the extract reduced the FEC by 84 % on day 7 and 83 % on day 35 compared to the control group. These results prompted a second experiment, using the same experimental design, but with the extract administered to the animals in a single dose of 5 mg/kg body weight. The result for the reduction in FEC in the levamisole-treated group was similar to that obtained in the first experiment, whereas in the group treated with a single dose of the extract, the reduction was significant from day 7, reaching 97 % by day 35 compared to the control group, with no significant difference from the levamisole-treated group. Regarding nematode species, on day 0, all treatments in the experiment showed a predominance of Haemonchus contortus, but other species such as Cooperia, and Oesophagostomum were also identified. On day 35, only Haemonchus contortus was identified in the extract-treated group and the levamisole-treated group, whereas Cooperia and Oesophagostomum species were also found in the control group. Toxicity tests for liver and kidney functions showed no alterations after administration of the single dose extract. These results demonstrate the in vivo anthelmintic activity of the hydroethanolic extract of Piper cubeba fruits and suggest its potential use as an alternative to synthetic chemicals in controlling parasites in sheep.

Discriminatory dose of nitroxynil and albendazole sulfoxide using a modified egg hatch test of Fasciola hepatica

Fasciolosis is a food-borne anthropozoonotic disease caused by Fasciola spp. that affects multiple hosts, including ruminants and humans. In vitro testing of anthelmintics is of interest to establish the drug's activity without the need for time-consuming and expensive in vivo assays. This study was set to establish a discriminatory dose (DD) by running a dose-titration in vitro experiment (egg hatch test, EHT) of albendazole sulfoxide (ABZ.SO) and nitroxynil (NTX) on eggs of a field strain of Fasciola hepatica. Eggs were recovered from adult parasites isolated from intact bovine livers obtained from a single farm in Paraná, Brazil (FhPar2022 strain) with no ABZ or NTX treatment history. Two hundred eggs were exposed to 18 and 14 concentrations of ABZ.SO and NTX, respectively, for 12h and incubated for 16 days. Egg development and integrity were determined every other day, establishing an index of morphological modification of the different phases. A concentration-dependent effect was observed for egg development in both compounds. ABZ.SO solutions prevent egg hatch, except for the two lowest concentrations. We observed no egg hatch at 6.250-100.0 μmol L-1 for NTX. NTX had an inhibition concentration of 50% (IC50) of 0.043 μmol L-1 with a correlation coefficient of (R2) 0.961. ABZ.SO had an IC50 of 0.00099 μmol L-1 with a low R2 of 0.417. Morphological damage was also associated with the increasing concentration of both drugs. Moreover, it was noted that most eggs that reached the eye spot type could hatch, except at 0.39 and 3.12 μmol L-1 of NTX. In ABZ.SO, hatching occurred only at 0.00038, 0.0007, and 0.0015 μmol L-1 concentrations. The obtained DDs of 0.043 μmol L-1 for NTX and 0.00099 μmol L-1 for ABZ.SO can be used to monitor efficacy in field isolates.

Prevalence, risk factors, and species diversity of strongylid nematodes in domesticated Thai horses: insights from ITS-2 rDNA metabarcoding

Strongylid nematodes represent a major health and performance concern for equids globally. However, the epidemiology of strongylid infections in horse populations remains largely unexplored in Thailand. This study investigated the prevalence of strongylid parasites and the associated risk factors in domesticated horses in Thailand. Additionally, the study utilized ITS-2 rDNA metabarcoding to characterize the diversity and co-occurrence patterns of strongylid species. Of the 408 horses examined, 50.98% tested positive for strongyle infection, with an average intensity of 445.67 ± 639.58 eggs. Notably, only 25.74% exhibited fecal egg counts of ≥ 200 eggs per gram (EPG), highlighting the need for targeted deworming protocols. Significantly higher EPG values were observed in yearling horses (p = 0.001) and those kept in outdoor pastures (p = 0.0001). Metabarcoding identified 15 strongylid species, with Cylicostephanus longibursatus being the most abundant (mean relative abundance: 37.30%, SD = 31.16%). No Strongylus species were detected. Alpha diversity analysis revealed no significant differences in species richness and evenness across horse groups, while beta diversity analysis showed significant dissimilarities (p = 0.004), primarily driven by Cylicostephanus longibursatus, Cyathostomum pateratum, and Cylicostephanus calicatus, which contributed to over 60% of the variation. Species co-occurrence patterns were largely random, with a limited number of positive (n = 5) and negative (n = 2) species pair associations. These findings provide essential insights into the current state of strongylid infections in Thai horses and offer a foundation for future research and management strategies.

Effectiveness of benzimidazole treatments against Haemonchus contortus in sheep and goats - Do they produce similar responses?

The primary aim of this study was to compare the in vivo responses to orally administered doses of albendazole (5 mg/kg body weight) between experimentally infected sheep and goats. Fifty-four Improved Valachian lambs and 54 Saanen goat kids were split into six groups of nine animals. The sheep and goats were infected with larvae of the gastrointestinal nematode parasite Haemonchus contortus containing 10, 20, 30, 40, 60, and 80 % of the isotype-1 β-tubulin gene codon 200 alleles previously shown to be associated with benzimidazole (BZ)-resistance. All groups of goats generally had higher mean eggs per gram (EPG) before treatment, which was significant (p<0.05) only for the group with 80 % resistance alleles. An in vivo faecal egg reduction test (FECRT) was used to determine the efficacy of albendazole (ABZ) eight days after treatment. Anthelmintic treatment significantly reduced the EPGs in the groups with 10, 20, and 80 % resistance alleles in sheep and with 10, 20, 30, and 40 % resistance alleles in goats. Differences in efficacy between the sheep and goats after the application of doses of ABZ recommended for sheep mostly ranged from 2 % to 10 %. The largest variation was in the group infected with worms containing 60 % resistance alleles, where the efficacy was 13 % higher in goats. Our secondary aims were to evaluate the data obtained from an in vitro egg hatch test (EHT) in sheep and goats and to compare these data with the results from the isotype-1 β-tubulin gene codon 200 pyrosequencing and the FECRT. The percentages of the BZ-resistance alleles were comparable with the mean hatching obtained in the EHT and were also supported by the FECRT data for all groups. The results of the in vivo tests should be verified in the future using in vivo surveys conducted in mixed breeds and infections in multiple species.

Treatment ineffectiveness towards Haemonchus contortus is highly prevalent in sheep and goat farms of North-Eastern Italy

BACKGROUND

Anthelmintic resistance (AR) is a global threat to grazing livestock farming. In Italy, anthelmintic efficacy remains high compared to other European countries, but many parts of the country haven't been investigated yet. Local veterinary practitioners from Trentino and Veneto regions reported suspected inefficacy towards anthelmintic drugs in some of their farms, prompting a study on AR in sheep and goat farms of northern Italy. The study aimed to assess anthelmintic effectiveness using genus-specific faecal egg count reduction tests (FECRT), to detect differences in treatment response among nematode genera involved in the infection.

RESULTS

Twelve farms (6 sheep and 6 goat farms) were included based on clinical suspicion of AR. Treatments were carried out with either benzimidazoles (BZ) or macrocyclic lactones (ML) Treatment was effective in 3/6 goat trials, with reduced effectiveness to BZ in two farms and to ML the last one. In sheep farms (6/6), effectiveness was consistently and more severely insufficient. Ineffectiveness was particularly high towards Haemonchus contortus, while Oesophagostomum/Chabertia maintained susceptibility in nearly all trials. Trichostrongylus/Teladorsagia exhibited intermediate results.

CONCLUSIONS

This study reveals diminished efficacy of both BZ and ML in small ruminant farms in north-eastern Italy, an area previously lacking data on the topic, except for goats in South Tyrol. Variability in treatment responses among nematode genera support suspicions of AR, and further concerns are raised by the prevalence of treatment ineffectiveness against the highly pathogenic Haemonchus contortus. This finding underscores the urgent need for comprehensive AR monitoring in the area and improved management practices to prevent further resistance development and protect livestock health.

In vitro anthelmintic activity and colocalization analysis of hydroxycinnamic acids obtained from Chamaecrista nictitans against two Haemonchus contortus isolates

This study assessed the in vitro anthelmintic activity of ethyl acetate extract (Cn-EtOAc) and its bioactive fractions (CnR3 and CnR5) obtained from Chamaecrista nictitans aerial parts against two Haemonchus contortus (Hc) isolates, one resistant (strain HcIVM-R) and another susceptible (strain HcIVM-S) to ivermectin. Ferulic acid and p-coumaric acid were identified in the bioactive fractions; therefore, their commercial standards were also assessed. A colocalization analysis between the ferulic acid commercial standard and eggs of the HcIVM-R strain was performed using confocal laser scanning microscopy and the ImageJ program. The ovicidal effects of the Cn-EtOAc extract, bioactive fractions and commercial compounds were tested through the egg hatching inhibition (EHI) assay on H. contortus isolates HcIVM-R and HcIVM-S. The Cn-EtOAc caused 88 % and 92 % EHI at 5000 µg/mL on HcIVM-R and HcIVM-S, respectively. Fractions CnR3 and CnR5 displayed the highest ovicidal activity against HcIVM-S, with effective concentrations (EC90) of 2134 and 601 µg/mL, respectively. Meanwhile, the commercial standards ferulic acid and p-coumaric acid also resulted in higher effectiveness on the same strain, with EC90 of 57.5 and 51.1 µg/mL. A colocalization analysis of ferulic acid and eggs of HcIVM-R revealed that this compound is localized to the cuticle surface of the embryo inside the egg parasite. The results demonstrated that both ferulic and p-coumaric acids interrupt the egg-hatching processes of the two Hc isolates. Both phenolic acids isolated from C. nictitans and commercial standards exhibited the best anthelmintic effect on HcIVM-S. These findings indicate that the phenolic acids were less effective in egg hatch inhibiting on the HcIVM-R strain compared to the HcIVM-S strain.

Occurrence of fenbendazole resistance in Parascaris spp. on breeding farms in Sweden

Anthelmintic resistance is an increasing problem in many gastrointestinal parasites of grazing animals. Among these, the equine roundworm, Parascaris spp., has developed wide-spread resistance to macrocyclic lactones over the past decades. Additionally, there are recent observations of emerging treatment failure of both tetrahydropyrimidine and fenbendazole. Therefore, the aims of this study were to further investigate the occurrence of fenbendazole resistance on breeding farms and to explore potential management-related risk factors associated with resistance in Parascaris spp. in Sweden. Eleven farms with 92 foals positive for Parascaris spp. were included in a faecal egg count reduction test during the years 2021-2023. According to the clinical protocol of the guidelines of the World Association for the Advancement of Veterinary Parasitology, fenbendazole resistance was present on four farms with efficacies varying from 45 % to 96 %. Having previously reported reduced efficacy on one of these farms, we can now confirm that fenbendazole resistance in Parascaris spp. has established. Farms with more than 40 yearly born foals had a significantly higher probability of having resistant Parascaris spp. Populations compared with smaller farms, (generalized linear model (GLM), t = 70.39, p < 0.001). In addition, there was a correlation between the number of foals on the farm and the frequency of yearly treatments showing that farms with < 20 foals were notably inclined to administer treatments twice during the first year (GLM, t=2.76, p < 0.05) in contrast to larger farms with > 40 foals that were using more frequent treatment intervals. In conclusion, this study confirms the establishment of fenbendazole resistance in Parascaris spp. populations on Swedish stud farms with the number of foals on the farm identified as a risk factor for development of anthelmintic resistance.

An Insight into Practices Associated with the Control of Internal Parasites in the Dairy Goat Herds of Romania: A Questionnaire Survey

The widespread and uncontrolled use of anthelmintic products has contributed to the emergence of anthelmintic resistance (AR). This phenomenon globally threatens the productivity and welfare of small ruminants. A questionnaire consisting of 34 questions was handed to 234 goat farmers across Romania to gain insight into control practices against internal parasites and the farmers' perception of the parasitic infections present in their herds and the efficacy of anthelmintic treatments. The majority of farmers (88.5%) admitted they had never submitted fecal samples for parasitological laboratory analysis, and 77.4% had treated the animals on their own. In general, the farmers dewormed their goats based on visual body weight estimation. Prophylactic anthelmintic treatment was practiced by more than 85% of the farmers. A traditional control approach based on treating the entire herd at fixed time intervals is widespread among Romanian goat and sheep farmers. The most commonly used anthelmintic drugs in the previous 3 years (2021-2023) were benzimidazoles (85.5%) and macrocyclic lactones (81.6%). Poor anthelmintic efficacy was suspected by 14.5% of farmers, and the minority (18.0%) considered internal parasites as a problem in their herds. Regarding the farmers' perception of the presence of parasites, there was a significant level of uncertainty. This is the first survey carried out in Romanian goat herds, and it provides up-to-date information on practices aimed at controlling internal parasites.

Reduction of egg reappearance period of cyathostomins in naturally infected horses after increasing doses of ivermectin in Brazil: a grim picture for sustainable parasite control

Cyathostomins are the largest group of parasites in horses that can be controlled by ivermectin (IVM). This study aimed to run a four-dose titration trial of IVM in 28 naturally infected Thoroughbred yearlings. The local Strongyle population had been recorded to be resistant to IVM (200 µg/kg). The parasite fecal egg count (FEC) was performed to investigate the egg reappearance period (ERP) of two and five weeks (w2pt and w5pt) after IVM treatment. FEC was > 1000 on day zero for all groups. Although 100% FEC reduction was reported at w2pt for all concentrations, the FEC at w5pt revealed < 83% efficacy. This study reports the reduction of ERP using the label dose as well as 300, and 400 µg/kg (double dose) of IVM. The protocol allowed IVM to significantly suppress FEC w2pt although not eliminating adult worms, failing to guarantee an extension of its protection period over 8 weeks. Moreover, the FEC at w5pt possibly means the infection was not cleared, and worms reestablished egg laying. We raised the possibility of withdrawing IVM of control programs when the drug has less than 80% FEC reduction at w5pt.

Green synthesis and anthelmintic activity of silver nanoparticles using Morus Alba Fruit extract against different stages of equine strongyles

The current study was designed to green synthesize silver nanoparticles (GRAgNPs) using Morus alba fruit extract and evaluate their nematicidal effects against strongyle nematodes compared to commercial silver nanoparticles (CAgNPs) in vitro. The nanoparticles were characterized by Ultraviolet-visual absorption spectrography, transmission electron microscopy, and X-ray diffraction. Next, uptake of AgNPs by the first stage larvae (L1), egg hatch inhibition (EHI) and the motility of infectious larvae (L3s), and the ultrastructural analysis of the eggs and worms were conducted. Moreover, some of oxidative/nitrosative stress indicators, including total antioxidant status content (TAC), protein carbonylation (PCO), lipid peroxidation (MDA), and DNA damage were assessed in the homogenized samples of strongyle L3s. We found that the GRAgNPs had spherical shape, 20-30 nm in diameter with rough surface. Following incubation with GRAgNPs at concentrations of 43.40, 21.70 and 10.85 ppm and CAgNPs at concentrations of 43.40 and 21.70, EHI was more than 90%. In addition, concentrations of 43.40 and 21.70 ppm of GRAgNPs led to inhibition of larval motility by more than 90%. The LC50 at 24 h of treatment for GRAgNPs and CAgNPs was determined to be 8.62 and 10.34 ppm, respectively. GRAgNPs and CAgNPs, in a concentration-dependent manner, resulted in the induction of oxidative/nitrosative stress evidenced by decreased TAC levels, and increased levels of MDA and PCO, together with increased DNA damage. The uptake of AgNPs by the L1 larvae revealed that FITC labeled GRAgNPs fluoresced with high intensity largely in the intestinal area. Scanning Electron Microscopy analysis of eggs and larvae revealed that GRAgNPs penetrated the cuticle of larvae, changed the tegmentum, and ultimately killed the worm. In conclusion, GRAgNPs had more robust anthelminthic effects than the standard antiparasitic and CAgNPs. They could be considered as a promising antiparasitic agent.

Faecal egg count reduction tests and nemabiome analysis reveal high frequency of multi-resistant parasites on sheep farms in north-east Germany involving multiple strongyle parasite species

Anthelmintic resistance in sheep parasitic gastrointestinal nematodes is widespread and a severe health and economic issue but prevalence of resistance and involved parasite species are unknown in Germany. Here, the faecal egg count reduction test (FECRT) was performed on eight farms using fenbendazole, ivermectin and moxidectin and on four farms using only moxidectin. A questionnaire was used to obtain data on management practices to potentially identify risk factors for presence of resistance. All requirements of the recently revised WAAVP guideline for diagnosing anthelmintic resistance using the FECRT were applied. Nematode species composition in pre- and post-treatment samples was analysed with the nemabiome approach. Using the eggCounts statistic package, resistance against fenbendazole, ivermectin and moxidectin was found on 7/8, 8/8 and 8/12 farms, respectively. No formal risk factor analysis was conducted since resistance was present on most farms. Comparison with the bayescount R package results revealed substantial agreement between methods (Cohen's κ = 0.774). In contrast, interpretation of data comparing revised and original WAAVP guidelines resulted in moderate agreement (Cohen's κ = 0.444). The FECR for moxidectin was significantly higher than for ivermectin and fenbendazole. Nemabiome data identified 4 to 12 species in pre-treatment samples and treatments caused a small but significant decrease in species diversity (inverse Simpson index). Non-metric multidimensional scaling and k-means clustering were used to identify common patterns in pre- and post-treatment samples. However, post-treatment samples were scattered among the pre-treatment samples. Resistant parasite species differed between farms. In conclusion, the revised FECRT guideline allows robust detection of anthelmintic resistance. Resistance was widespread and involved multiple parasite species. Resistance against both drug classes on the same farm was common. Further studies including additional drugs (levamisole, monepantel, closantel) should combine sensitive FECRTs with nemabiome data to comprehensively characterise the anthelmintic susceptibility status of sheep nematodes in Germany.

Lack of Efficacy of Albendazole against Dicrocoelium dendriticum Infection in a Sheep Farm in France

Dicrocoeliosis is a common parasitic disease in European sheep farming. The prevalence of infection by this parasite can reach almost 70% in areas where the environment is favorable to intermediate hosts. In France, only one drug is currently available for the treatment of dicrocoeliosis: albendazole at a dose of 15 mg/kg in a single administration. However, a control coproscopy following a routine treatment led us to suspect that the efficacy of albendazole against Dicrocoelium dendriticum had diminished. Therefore, we carried out an efficacy test on 15 animals by treating them with albendazole at a dose of 15 mg/kg and performing a coproscopy on D0 and a control coproscopy 14 days later. We obtained a 39% reduction in the excretion of D. dendriticum eggs. This shows a reduction in the expected efficacy of albendazole, which is normally more than 90% in other studies involving this molecule at a dosage of 15 mg/kg. These results are of major concern as albendazole is currently the only drug available in France to treat dicrocoeliosis.

Unravelling the Effectiveness of Anthelmintic Treatments on Equine Strongyles on Irish Farms

Over the preceding decades, the widespread dependence on anthelmintic drugs for managing nematodes in grazing equids has given rise to resistance against commonly used anthelmintics in various countries. This study explores the prevalence of anthelmintic resistance across 44 horse farms in Ireland. Anthelmintic efficacy was evaluated through fecal egg count reduction (FECR) tests employing the mini-FLOTAC technique. Resistance to benzimidazoles was identified in 12 out of 14 farms (FECR range: 0.00% to 86.2%). Ivermectin resistance was observed on two farms, one with an FECR of 80.70% and another with an FECR of 96.10% (lower 95% high probability density interval (HPD) <90%, 11.70%). On the remaining six farms, the reduction with ivermectin still exceeded 95%. The reduced efficacy of moxidectin was noted on two farms (FECR = 86.90% and 93.50%) and on a third farm with an FECR of 99.50 and a lower HPD interval < 90% at 24.00%. In summary, these findings emphasize the urgent need for alternative strategies in equine strongyle control that reduce reliance on anthelmintics and prioritize effective management practices on Irish equine farms to hinder the impending development of drug-resistant parasite populations.

Effect of cattle and horse feces storage methods on Nematode egg viability and sensitivity for egg hatch test

The aim of the present study was to validate methods of stool sample conservation for the egg hatch test (EHT). This study involved the use of a bovine naturally infected predominantly by Cooperia spp. and one equine naturally infected predominantly by cyathostomins characterized as susceptible to benzimidazoles in the EHT. Fecal samples were submitted to three treatments: aerobic methods (anaerobic storage in plastic bottles, anaerobic storage in vacuum-sealed bags or aerobic storage in plastic bags), under two temperature conditions (room temperature and refrigeration) analyzed at four different assessment times (48, 72, 96 and 120 h). As the standard test, an assay was also performed within 3 h. The tests were performed in triplicate for each drug concentration and with three experimental repetitions at one-week intervals. Two criteria were used for the storage methods: hatchability in the negative control group and sensitivity of the eggs to thiabendazole, comparing the EC50 and 95% confidence interval for each treatment to those of the standard test and the other repetitions. Bovine samples can be stored for up to 96 h and refrigerated vacuum storage can be used, ensuring hatchability of the negative control and sensitivity of the eggs to thiabendazole. For equine samples, no forms of storage were indicated due to the variation among the repetitions and the reduction in the sensitivity of the eggs to thiabendazole, which could result in a false positive detection of resistance.

Comparison of P-glycoprotein gene expression of two Haemonchus contortus isolates from Yucatan, Mexico, with resistant or susceptible phenotype to ivermectin in relation to a susceptible reference strain

The variability in the expression of different P-glycoprotein (P-gp) genes in parasitic nematodes of ruminants such as Haemonchus contortus (Hco-pgp) may be caused by different factors including nematode biology, geographical region and anthelmintic pressure. This study analysed the relative expression level of 10 P-gp genes in two H. contortus (Hco-pgp) field isolates from Yucatan, Mexico: 1) PARAISO (IVM-resistant) and 2) FMVZ-UADY (IVM-susceptible). These isolates were compared with a susceptible reference isolate from Puebla, Mexico, namely "CENID-SAI". In all cases H. contortus adult males were used. The Hco-pgp genes (1, 2, 3, 4, 9, 10, 11, 12, 14 and 16) were analysed for each isolate using the RT-qPCR technique. The Hco-pgp expressions were pairwise compared using the 2-ΔΔCt method and a t-test. The PARAISO isolate showed upregulation compared to the CENID-SAI isolate for Hco-pgp 1, 3, 9, 10 and 16 (P < 0.05), and the PARAISO isolate showed upregulation vs. FMVZ-UADY isolate for Hco-pgp 2 and 9 (P < 0.05), displaying 6.58- and 5.93-fold differences (P < 0.05), respectively. In contrast, similar Hco-pgp gene expression levels were recorded for FMVZ-UADY and CENID-SAI isolates except for Hco-pgp1 (P <0.1), which presented a significant upregulation (6.08-fold). The relative expression of Hco-pgp allowed confirming the IVM-resistant status of the PARAISO isolate and the IVM-susceptible status of the FMVZ-UADY isolate when compared to the CENID-SAI reference isolate. Therefore, understanding the association between the Hco-pgp genes expression of H. contortus and its IVM resistance status could help identifying the genes that could be used as molecular markers in the diagnosis of IVM resistance. However, it is important to consider the geographic origin of the nematode isolate and the deworming history at the farm of origin.

In vitro ovicidal and larvicidal activity of a hydroalcoholic extract and its fractions from Cyrtocarpa procera fruits on Haemonchus contortus

This study describes the in vitro anthelmintic effect of a hydroalcoholic extract (HA-E) and its fractions from Cyrtocarpa procera fruits against Haemonchus contortus eggs and infective larvae. The HA-E was subjected to bipartition using ethyl acetate, which resulted in an aqueous fraction (Aq-F) and an organic fraction (EtOAc-F). The HA-E and both fractions were tested using the egg hatching inhibition assay (EHIA) and the larval mortality test (LMT). Fractionation of the EtOAc-F was achieved using different chromatographic processes, i.e., open glass column and HPLC analysis. Fractionation of the EtOAc-F gave 18 subfractions (C1R1-C1R18), and those that showed the highest yields (C1R15, C1R16, C1R17 and C1R18) were subjected to anthelmintic assays. The HA-E and the EtOAc-F displayed 100% egg hatching inhibition at 3 and 1 mg/mL, respectively, whereas Aq-F exhibited 92.57% EHI at 3 mg/mL. All subfractions tested showed ovicidal effect. Regarding the larval mortality test, HA-E and EtOAc-F exhibited a larvicidal effect higher than 50% at 50 and 30 mg/mL, respectively. The subfractions that showed the highest larval mortality against H. contortus were C1R15 and C1R17, with larval mortalities of 53.57% and 60.23% at 10 mg/mL, respectively. Chemical analysis of these bioactive subfractions (C1R15 and C1R17) revealed the presence of gallic acid, protocatechuic acid, and ellagic acid. This study shows evidence about the ovicidal and larvicidal properties of C. procera fruits that could make these plant products to be considered as a natural potential anthelmintic agents for controlling haemonchosis in goats and sheep.

In vitro and in vivo anthelmintic effect of essential oil obtained from Thymus capitatus flowers against Haemonchus contortus and Heligmosomoides polygyrus

Sheep haemonchosis is a disease that causes serious losses in livestock production, particularly with the increase of cases of anthelmintic resistance around the world. This justifies the urgent need of alternative solutions. The aim of this study was to determine the chemical profile, in vitro, and, in vivo, anthelmintic properties of Thymus capitatus essential oil. To evaluate the, in vitro, anthelmintic activity of the T. capitatus EO on Haemonchus contortus, two tests were used: egg hatch assay (EHA) and adult worm motility (AWM) assay. The nematicidal effect of this oil was evaluated, in vivo, in mice infected artificially with Heligmosomoides polygyrus using faecal egg count reduction (FECR) and total worm count reduction (TWCR). Chromatographic characterization of T.capitatus composition using gas chromatography coupled to mass spectrometry (GC-MS) demonstrated the presence of carvacrol (81.16%), as the major constituents. The IC50 values obtained was 1.9 mg/mL in the EHT. In the AWM assay; T. capitatus essential oil achieved 70.8% inhibition at 1 mg/mL after 8 h incubation. The in vivo, evaluation on H. polygyrus revealed a significant nematicidal effect 7 days post-treatment by inducing 49.5% FECR and 64.5% TWCR, using the highest dose (1600 mg/kg). The results of present study, demonstrate that T.capitatus EO possess a significant anthelmintic properties. Furthermore, it could be an alternative source of anthelmintic agents against gastrointestinal infections caused by H. contortus.

Surveillance of Ancylostoma caninum in naturally infected dogs in Quebec, Canada, and assessment of benzimidazole anthelmintics reveal a variable efficacy with the presence of a resistant isolate in imported dogs

Ancylostoma caninum is a widely prevalent parasitic nematode in dogs across the world. There has been a notable increase in reports of anthelmintic resistance in A. caninum within the United States of America in recent years, which has led us to investigate the potential of this scenario in Canada. The study objectives were to assess the prevalence of A. caninum in two different groups, including a colony of rescued dogs in Canada and three imported Greyhound dogs from USA, and to evaluate the efficacy of two benzimidazole (BZ) anthelmintics against A. caninum, complemented with a molecular genetic analysis adapted to low prevalence. Fecal samples were collected at pre- and post-treatment with fenbendazole for the native shelters-origin group, and a combination of anthelmintic formulations, including the pro-BZ febantel for the USA-origin group. The coprology analyses found several genera of internal parasites. Canine ancylostomiasis was the most prevalent parasitosis with 30.77% in the native group and 100% in the USA group, but with overall low average of A. caninum eggs per gram. Through the fecal egg count reduction test (FECRT), applying a cut-off at 90% as baseline of egg reduction for successful efficacy, BZ showed variable efficacy. Furthermore, molecular analysis confirmed the presence of A. caninum in both groups of dogs and found differences in the genetics linked to BZ resistance on the A. caninum β-tubulin isotype 1 gene. In the isolate from the native group, both codons 167 and 200 were homozygous without the presence of single nucleotide polymorphism (SNP). In contrast, the selected isolate from the USA group, showed a homozygous allele at position 200 and a heterozygous SNP at position 167. The latter was congruent with the low efficacy in FECRT and agrees with the recent findings of USA A. caninum isolate resistant phenotype to the BZ anthelmintics. The limitations of the study include an overall low eggs-per-gram in both canine groups, and the shortage of additional fecal samples from the USA group, restraining the molecular analysis only to one out of the three Greyhounds. This study provided some insights on the efficacy of BZs against A. caninum and revealed the presence of BZ resistant isolates in imported dogs in Quebec, Canada. All this information should be considered, for choosing the best strategy in the control of A. caninum using anthelmintic drugs.

Interaction between bacterial microbiota and nematode parasite communities in sheep's gastrointestinal tract

The economic impact of gastrointestinal (GI) nematode infections on livestock production is well documented worldwide. Increasing evidence supports the hypothesis that parasite colonization induces significant changes in the GI tract environment and, therefore, in the landscape where the microbiota and parasites occur. Understanding the interactions between bacterial and parasite populations in the digestive tract of livestock may be useful to design parasite control strategies based on microbiota modification. The aims of this work were to investigate the impact of the oxytetracycline-mediated manipulation of the gut microbial community on the composition of GI nematode populations in naturally infected sheep and to explore changes in the GI microbial communities after nematode population treatment with the anthelmintic compound monepantel. Extensive manipulation of the GI microbiota with a therapeutic dose of the long-acting oxytetracycline formulation did not induce significant changes in the GI nematode burden. The gut microbiota of treated animals returned to control levels 17 days after treatment, suggesting strong resilience of the sheep microbial community to antibiotic-mediated microbiota perturbation. A significant decrease of the bacterial Mycoplasmataceae family (Log2FC = -4, Padj = 0.001) and a marked increase of the Methanobacteriaceae family (Log2FC = 2.9, Padj = 0.018) were observed in the abomasum of sheep receiving the monepantel treatment. While a comprehensive evaluation of the interactions among GI mycoplasma, methanobacteria and nematode populations deserves further assessment, the bacteria-nematode population interactions should be included in future control programs in livestock production. Understanding how bacteria and parasites may influence each other in the GI tract environment may substantially contribute to the knowledge of the role of microbiota composition in nematode parasite establishment and the role of the parasites in the microbiota composition.

First evaluation and detection of ivermectin resistance in gastrointestinal nematodes of sheep and goats in South Darfur, Sudan

In Sudan, resistance to benzimidazoles has been reported recently in cattle and goats from South Darfur. Herein, ivermectin efficacy against gastrointestinal nematodes (GINs) was evaluated in sheep and goats in three study areas in South Darfur. The faecal egg count reduction test (FECRT) was used to evaluate the efficacy of ivermectin in sheep and goats naturally infected with GINs in the region of Bulbul (goats: n = 106), Kass (goats: n = 40) and Nyala (Domaia (sheep: n = 47, goats: n = 77) and the University farm (goats: n = 52)), using different treatment plans, and the efficacy was evaluated 12 days after treatment. Ivermectin efficacy was also evaluated in goats experimentally infected using local Haemonchus contortus isolates from Kass and Nyala. Nematodes surviving ivermectin treatment in goats in Bulbul and Nyala were harvested and larvae used to infect worm-free male sheep (n = 6, ≤6 months old). Infected sheep were dosed subcutaneously with ivermectin every eight days with increasing doses from 0.2 mg/kg to 1.6 mg/kg bodyweight (bw). Reduced ivermectin efficacy was identified in sheep and goats in the four study locations. Using a paired statistic, the efficacy of a therapeutic dose in sheep was 75.6% (90% upper credible limit (UCrL): 77.5%), while twice the recommended dose led to a reduction of 92.6% (90% UCrL: 93.3%). In goats, the FECRs of a therapeutic dose were 72.9-95.3% (90% UCrL range: 73.6-95.7%) in Bulbul, Nyala Domaia, Nyala University farm and Kass. Twice the dose recommended for goats in Bulbul revealed a 90% UCrL of 87.6%. All post-treatment faecal cultures contained only Haemonchus spp. larvae. The experimental infection trials in sheep and goats supported our findings from field trials and calculated upper 90% CrL of below 98.9%. For the first time highly ivermectin resistant H. contortus populations have been identified in sheep and goats in Sudan, and resistance was experimentally confirmed.

Strongylids of Domestic Horses in Eastern Slovakia: Species Diversity and Evaluation of Particular Factors Affecting Strongylid Communities

PURPOSE

This study aimed to examine the species diversity and structure of the strongylid community in domestic horses in Eastern Slovakia. Also, an analysis of the impact of age, sex, and collection location factors on the strongyid communities was performed.

METHODS

Twenty-seven horses 1.5-21 years old from two farms in eastern Slovakia with different horse-management conditions were studied. Strongylids were collected after horse treatments with Noromectin (0.2 mg ivermectin); 66,170 specimens were collected and identified. Faecal egg count reduction test (FECRT) was performed following fenbendazole (FBZ) and ivermectin (IVM) treatments.

RESULTS

Twenty-four strongylid species were found; horses were infected with 6 to 16 (average = 11.7) species. Six cyathostomin species (Cylicocyclus nassatus, Cyathostomum catinatum, C. pateratum, Cylicostephanus longibursatus, C. goldi, C. calicatus) were the most prevalent; C. catinatum was the dominant species in both farms (Berger-Parker index 0.34 and 0.42). The structure of the strongylid community was multimodal with dominant, subdominant, background, and rare species. The Mantel test showed that horse age and sex did not significantly affect the nematode infracommunity composition (p > 0.05), while the impact of the collection location (farm) was significant (p = 0.03). Additionally, C. longibursatus was identified as the species contributing significantly to the observed farm differences. Strong resistance to FBZ was documented on both farms (FECRT was 36.4% and 22.7%); IVM resistance was not observed (FECRT = 100%).

CONCLUSION

This study presents the first report on the strongylids parasitizing domestic horses in Eastern Slovakia and gives basic information for further studies of horse parasites and their control in the region.

Anthelmintic Activity of Saussurea costus (Falc.) Lipsch. Against Ascaridia galli, a Pathogenic Nematode in Poultry: In Vitro and In Vivo Studies

AIM OF THE STUDY

The growing resistance of helminth parasites to currently available commercial anthelmintic drugs, combined with apprehensions regarding detrimental chemical residues in livestock products, has sparked an interest in exploring medicinal plants as an alternative strategy for treating helminthiasis. As a result, this study was designed to investigate the anthelmintic activity of crude methanolic extracts (CME) of Saussurea costus root on Ascaridia.galli, a pathogenic nematode of poultry.

MATERIALS AND METHODS

In vitro, the anthelmintic effect of Saussurea costus root was evaluated in comparison to commercial anthelmintic, levamisole on the adult nematode parasites, A.galli using worm motility inhibition (WMI) test. The CME of S.costus was also evaluated for in vivo anthelmintic activity in chickens experimentally infected with Ascaridia galli. For the in vivo study, one hundred-day-old chickens were orally infected with embryonated eggs of A. galli worms. The efficacy of the plant extract as an anthelmintic was assessed through two tests: faecal egg count reduction (FECR) test and worm count reduction (WCR) test. The study investigated three distinct doses of plant extract under in vivo setup: 500 mg kg-1 body weight (bw), 1000 mg kg-1 bw, and 2000 mg kg-1 bw.

RESULTS

In vitro, all the tested concentrations of S.costus (25 mg/ml, 50 mg/ml, and 100 mg/ml) showed a significant (P < 0.001) anthelmintic effects on live adult A. galli worms in terms of inhibition of worm motility at different hours post-treatment. At the highest concentration of the extract, we observed worm motility inhibition of 100% at 24 h post-exposure. On day 14 post-treatment, all birds were slaughtered, and adult A. galli worms were subsequently retrieved from their small intestines. Birds treated with CME extract of S. costus root exhibited a significant (P < 0.001) reduction in faecal egg count. However, the administration of the extract at the dosage of 500 mg kg-1bw to the birds did not reveal any significant (P > 0.05) differences in the worm count compared to the negative control group. The CME of S. costus at a dose of 2000 mg kg-1bw showed the highest anthelmintic activity by inducing 83.10% FECR and 76.47% WCR.

CONCLUSION

In conclusion, the root extract of S. costus has a promising anthelmintic activity on A. galli as demonstrated by the results of the present experiment.

Phytochemicals, antioxidant ability and in vitro anthelmintic activity of crude extracts from Vitexnegundo leaves against Haemonchus contortus

The aim of this study was to evaluate the in vitro anthelmintic effect of crude aqueous, methanol, ethanol, hydro alcohol and acetone extracts of Vitex negundo leaves against Haemonchus contortus eggs and larvae. Phytochemical analysis to identify the number of compounds in extracts was done by chemical tests and gas chromatography coupled to a mass spectrophotometer detector (GC-MS). First off all the effectiveness of dried plant materials was evaluated on larval development by mixing powdered material (no nano particles) to faecal cultures from donor sheep. Adding powder to the faecal culture resulted into 100% inhibition in larval development at 200 and 300 mg/g of faeces. The anthelmintic activity was assessed using the egg hatch assay (EHA) and the larval mortality assay (LMA). Comparison of mean inhibition percentage of egg embryonation, mean inhibition percentage of egg hatching and mean percentage of larval mortality at different concentrations with control was performed by one-way ANOVA. The means were compared for statistical significance using DMRT at P < 0.05. For both the assays, 50% inhibitory concentration (IC50) and lethal concentration (LC50) were calculated by probit analysis. Chemical test revealed presence of high concentration of saponin and flavoinoids and moderate concentration of total phenols in leaves. The antioxidant activity (radical scavenging activity, RSA %) measured was 35.47%. On GC-MS, the methanolic leaves extract revealed 30 phyto-compounds. On EHA, there was marked effect on inhibition of egg hatching by aqueous, hydro alcohol and acetone extracts. On LMA all the five extracts showed excellent larvicidal activity. V. negundo leaves methanol extract mediated silver nanoparticles were found very effective at much lower concentrations as compared to crude methanol extract. The results indicated that the V. negundo leaves crude extracts possessed excellent in vitro ovicidal and larvicidal properties against H. contortus which needs more investigation, especially in vivo trials for the control of parasite.

Exploiting fly ash as an ecofriendly pesticide/nematicide on Abesmoschus esculuntus: Insights into soil amendment-induced antioxidant fight against nematode mediated ROS

Conventional pest control measures, such as chemical pesticides and nematicides, have limited efficacy and raise environmental concerns, necessitating sustainable and eco-friendly alternatives for pest management. Therefore, to find a complementary eco-friendly pesticide/nematicide, this study investigated the role of fly ash (FA) in managing a notorious pest, Meloidogyne javanica and its impact on the growth and physiology of Abelmoschus esculentus. Molecular characterization using SSU and LSU rDNA gene markers confirmed the identity of Indian M. javanica as belonging to the same species. Biotic stress induced by nematode infection was significantly alleviated (P < 0.05) by FA application at a 20% w/v, regulating of ROS accumulation (44.1% reduction in superoxide anions and 39.7% reduction in hydrogen peroxide content) in the host plant. Moreover, FA enhanced antioxidant defence enzymes like superoxide dismutase (46.6%) and catalase (112%) to combat nematode induced ROS. Furthermore, the application of FA at a 20% concentration significantly improved the biomass and biochemical attributes of okra. Fly ash also upregulated the activity of the important osmo-protectant proline (11.5 μmol/g FW) to mitigate nematode stress in host cells. Suppression of disease indices like gall index and reproduction factor, combined with in-vitro experiments, revealed that FA exhibits strong nematode mortality capacity and thus can be used as a sustainable and eco-friendly control agent against root-knot nematodes.

Occurrence of gastrointestinal nematodes in lambs in Norway, as assessed by copromicroscopy and droplet digital polymerase chain reaction

BACKGROUND

Gastrointestinal nematodes (GINs) have a major impact on sheep production, health, and welfare worldwide. Norway is no exception, but there are only a few studies on the prevalence of GINs in Norwegian sheep. The aim of this study was to investigate the current occurrence of the most important nematodes in sheep flocks in Norway. Faecal samples were collected from flocks in 2021/2022, mainly from three geographical regions in Norway, i.e., northern, eastern, and western. In each of 134 flocks included, individual samples from 10 lambs (autumn) were pooled. Third stage larvae (L3) were cultivated and harvested (Baermann method) from the pooled samples. The DNA was then extracted and further analysed using droplet digital PCR (ddPCR). This enables assessment of the proportions of the three most important nematode species/genera, i.e., H. contortus, T. circumcincta, and Trichostrongylus. The fractional abundance/relative proportion of each species/genus was assessed by performing duplex assays with universal strongyle and species/genus-specific primers and probe sets. In addition, the occurrence of Nematodirus eggs was assessed by standard faecal egg counts (i.e., McMaster method).

RESULTS

Of the 134 flocks sampled, 24 were from the northern region, 31 from eastern, and 71 from western Norway. In addition, some flocks from central (n = 7), and southern (n = 1) Norway were included. Among the sampled flocks, T. circumcincta occurred most commonly (94%), followed by H. contortus (60%) and Trichostrongylus (55%), and Nematodirus (51%). In general, mixed infections were observed, with 38% and 18% of flocks infected with three or all four genera, respectively.

CONCLUSIONS

The results of this study indicate that GINs are widespread in Norway. Teladorsagia circumcincta seems to be present in most flocks based on this screening. Moreover, the results show that Nematodirus spp. infect lambs throughout the country, predominantly N. battus, and indicate that this nematode has become more abundant, which could lead to an increase in nematodirosis.

BEVA primary care clinical guidelines: Equine parasite control

BACKGROUND

There is a lack of consensus on how best to balance our need to minimise the risk of parasite-associated disease in the individual horse, with the need to limit the use of anthelmintics in the population to preserve their efficacy through delaying further development of resistance.

OBJECTIVES

To develop evidence-based guidelines utilising a modified GRADE framework.

METHODS

A panel of veterinary scientists with relevant expertise and experience was convened. Relevant research questions were identified and developed with associated search terms being defined. Evidence in the veterinary literature was evaluated using the GRADE evidence-to-decision framework. Literature searches were performed utilising CAB abstracts and PubMed. Where there was insufficient evidence to answer the research question the panel developed practical guidance based on their collective knowledge and experience.

RESULTS

Search results are presented, and recommendation or practical guidance were made in response to 37 clinically relevant questions relating to the use of anthelmintics in horses.

MAIN LIMITATIONS

There was insufficient evidence to answer many of the questions with any degree of certainty and practical guidance frequently had to be based upon extrapolation of relevant information and the panel members' collective experience and opinions.

CONCLUSIONS

Equine parasite control practices and current recommendations have a weak evidence base. These guidelines highlight changes in equine parasite control that should be considered to reduce the threat of parasite-associated disease and delay the development of further anthelmintic resistance.

A national survey of anthelmintic resistance in ascarid and strongylid nematodes in Australian Thoroughbred horses

This study quantified the extent of anthelmintic resistance (AR) in ascarid and strongylid nematodes against commonly used anthelmintics in Australian Thoroughbred horses. Faecal egg count reduction tests (FECRTs, n = 86) and egg reappearance period (ERP) tests were conducted on 22 farms across Australia. Faecal egg counts (FECs) were determined using the modified McMaster technique, and percent faecal egg count reduction (%FECR) was calculated using the Bayesian hierarchical model and hybrid Frequentist/Bayesian analysis method. The results were interpreted using old (published in 1992) and new (2023) research guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP). The species composition of strongylid nematodes was detected utilising a DNA-metabarcoding method using pre- and post-treatment samples. Resistance was observed in strongylid nematodes to commonly used single-active and combination anthelmintics, including ivermectin (IVM %FECR range: 82%-92%; 95% lower credible interval (LCI) range: 80%-90%), abamectin (ABM: 73%-92%; 65%-88%), moxidectin (MOX: 89%-91%; 84%-89%), oxfendazole (OFZ: 0%-56%; 0%-31%) and its combination with pyrantel (OFZ + PYR: 0%-82%; 0%-78%). Resistance in Parascaris spp. was observed to IVM (10%-43%; 0%-36%), ABM (0%; 0%) and MOX (0%; 0%). When the new thresholds recommended by the WAAVP were used, AR was detected in six additional FECRTs for strongylids and three more tests for Parascaris spp., introducing resistance to OFZ and OFZ + PYR in the latter. Shortened ERPs (4-6 weeks) of strongylids were observed in 31 FECRTs in which AR was not detected at 2 weeks post-treatment for all the anthelmintics tested. Among cyathostomins, Cylicocyclus nassatus, Cylicostephanus longibursatus and Coronocyclus coronatus were the most prevalent species at 2 weeks post-treatment, whereas the main species appearing at five weeks following treatments with macrocyclic lactones were Cylicocyclus nassatus, Cylicostephanus longibursatus and Cylicocyclus ashworthi. After treatment with OFZ + PYR, the latter three, plus Coronocyclus coronatus and Cyathostomum catinatum, were detected at 5 weeks post-treatment. Overall, the study highlights the prevalence of AR in both ascarids and strongylid nematodes against commonly used anthelmintic products to control worms in Australian horses. The results indicate that ML combination products provided acceptable efficacy at 2 weeks. However, ERP calculations suggest that products work less effectively than previously measured. It is suggested to regularly monitor the efficacy of the anthelmintics and consider changing the worm control practices to better manage worms and AR in Australian horses.

Faecal egg count reduction test in goats: Zooming in on the genus level

The faecal egg count reduction test (FECRT) is the most widely used method to assess treatment efficacy against gastrointestinal nematodes (GIN). Information on genera composition of the GIN community is not available with this test and it is commonly obtained by identifying cultured third-stage larvae (L3) or through molecular assays in the post-treatment survey, but results provided are usually only qualitative or semi-quantitative. The updated WAAVP guidelines now recommend assessing anthelmintic efficacy for each GIN genus/species separately (genus-specific FECRT), but this approach is poorly employed in Europe and in goats especially. For this reason, four FECRT trials were conducted using oxfendazole and eprinomectin in two Italian goat farms. Samples were processed individually using the McMaster technique and then pooled to create two samples from faeces of 5 animals each. Pooled samples were analysed using the McMaster and cultured for seven days at 26°C to obtain L3s. The genus-specific FECRT was based on larval identification, integrating coproculture and FEC results. Larvae were identified as Haemonchus, Trichostrongylus, Teladorsagia, Oesophagostomum / Chabertia and Bunostomum. Molecular assays (a multiplex real-time PCR and two end-point PCRs) were also implemented on pooled samples to support the morphological identification. The Spearmann Rho test confirmed a high correlation between the two approaches (Rho = 0.941 and Rho = 0.914 respectively for Haemonchus and Trichostrongylus, the two most common genera). Both oxfendazole and eprinomectin were effective in one farm, while none in the other farm (FECR = 75.9% and 73.3% respectively). In the second farm, the genus-specific FECRT highlighted a different response to treatment among genera: oxfendazole lacked efficacy against both Haemonchus and Trichostrongylus spp., eprinomectin only against Haemonchus, while all other genera were susceptible to both drugs. This study brings new attention on the importance of adopting a genus-specific approach to identify and quantify differences in susceptibility to anthelmintics among genera in goats, providing support for FECRT interpretation, anthelmintic resistance evaluation and evidence-based GIN control.

In Vitro anthelmintic efficacy of medicinal plant essential oils against Marshallagia marshalli: Evidence on oxidative/nitrosative stress biomarkers, DNA damage, and egg hatchability

One of the major public health problems is drug resistance in parasitic diseases. It is therefore important to find new active ingredients to combat parasites. Herbal products such as essential oils (EOs) may show promise in treating infections caused by gastrointestinal nematodes (GINs). This study investigated the in vitro anthelmintic activity of the EOs of Lavandula angustifolia and Quercus infectoria against Marshallagia marshalli. The in vitro study was based on an egg hatch test (EHT), adult and larval motility inhibition tests, DNA damage, and several biomarkers of oxidative/nitrosative stress, including superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GSH -Px], protein carbonylation [PCO], malondialdehyde [MDA], total antioxidant status [TAS], and nitric oxide levels [NO]. Different concentrations of Lavandula angustifolia and Quercus infectoria EOs (1, 5, 10, 25 and 50 mg/ml) were used to determine the anthelmintic effect on three stages of the life cycle of M. marshalli, i.e. eggs, larvae and adult parasites, for 24 hr. The results showed that EOs of L. angustifolia and Q. infectoria play an important role as anthelmintics. These essential oils significantly reduced the egg hatching and motility of larval and adult worms. This anthelmintic effect is dependent on concentration and time. Furthermore, the EOs of L. angustifolia and Q. infectoria caused oxidative/nitrosative stress (reduced SOD, GSH-Px and CAT and increased MDA, PCO and NO) and DNA damage, thereby providing significant antihelminthic effects. Based on the results, it seems that the EOs extracted from L. angustifolia and Q. infectoria may be effective in the control and treatment of M. marshalli infections. Further research is needed to investigate their potential for in vivo use in the treatment of parasitic infections.

Periodicity of Ascaridia galli egg excretion in experimentally infected chicken in the Philippines

The periodicity of parasite egg excretion refers to variations in the number of eggs produced across time, with significant implications in optimizing diagnostic procedures and conducting the Fecal Egg Count Reduction Test (FECRT). Here, we explore whether Ascaridia galli egg excretion varies across time under Philippine conditions, thus informing the best time to collect fecal samples during flock health examination. A time-course analysis was performed in chickens (N = 12) experimentally infected with A. galli, isolated from a naturally infected Philippine native chicken. We examined the fecal egg per gram (EPG) count at 3-h intervals for 3 days, starting from 5:00-6:00 h AM to the following day at 1:00-2:00 h AM. Our results showed a consistent daily egg excretion pattern with a peak EPG count in the morning that abruptly declined in the afternoon and lowest in the evening. The EPG counts correlated with the amount of excreta produced, suggesting that A. galli fecundity corresponds to the timing of host defecation. Our results imply that the best time to collect fecal samples for A. galli diagnosis and FECRT in Philippine conditions should be from sunrise until late morning when parasite EPG count and host excreta production are at their highest.

Exploring AMH levels, homeostasis parameters, and ovarian primordial follicle activation in pubertal infected sheep on a high-protein diet

"Exploring AMH Levels, Homeostasis and Primordial Follicle Activation in Pubertal Infected Sheep on a High Protein Diet ". The first activation wave of ovarian primordial follicles is part of the onset of puberty and fertility. Abomasal helminth infection may cause an undesirable delay in puberty manifestation. Helminth-infected animals demand a higher amount of protein in their diet to repair the damage caused by the parasite in sheep's tissues, replenish the blood losses, and build the host's immune response. Helminths become resistant to drug therapy shortly after being exposed to a new treatment. Besides, there is the possibility of contamination by anthelmintic drugs in ovine products, possibly affecting human health and the environment. This study's objective was to evaluate if ovarian and clinical parameters can be improved by supplementing their diet with protein, offering a more sustainable management approach than relying on anthelmintic usage. We used a 2 × 2 factorial model where eighteen ewe lambs (Ovis aries) between 6 and 7 months old - born to the same ram - were fed one of two diet protein levels (12% or 19%). After 35 days on this diet, they were infected or left uninfected with 10,000 Haemonchus contortus L3 larvae. We evaluated Anti-Mullerian Hormone serum levels, blood cells and biochemical parameters at four different time points. Following 42 days of infection and 77 days on the diet, the lambs had their left ovaries removed, and we examined ovarian morphometrics through histological analysis. The groups Supplemented Protein-Infected(n = 5), Control Protein- Infected(n = 5), Supplemented Protein-Not Infected (n = 4) and Control Protein-Not Infected (n = 4) did not differ in their bodyweight gain. In the factorial ANOVA analysis examining the relationship between plasma protein, diet, and infection, the protein level of the diet showed significance (p = 0.02). Primordial follicle size varied with the interaction between diet and infection (p < 0.05), and oocyte size was affected by the level of protein in the diet (p = 0.047). Additionally, to understand how all homeostasis parameters relate to the primordial follicle and oocyte size, we applied an explanatory linear mixed model. In conclusion, serum AMH levels remained stable despite the infection and variations in diet protein levels, indicating its reliability as a marker for ovarian reserve in pubertal sheep. The number of blood cells, biochemical parameters, and primordial follicle activation were affected by both diet and infection.

Transcriptome reveals the roles and potential mechanisms of lncRNAs in the regulation of albendazole resistance in Haemonchus contortus

BACKGROUND

Haemonchus contortus (H. contortus) is the most common parasitic nematode in ruminants and is prevalent worldwide. H. contortus resistance to albendazole (ABZ) hinders the efficacy of anthelmintic drugs, but little is known about the molecular mechanisms that regulate this of drug resistance. Recent research has demonstrated that long noncoding RNAs (lncRNAs) can exert significant influence as pivotal regulators of the emergence of drug resistance.

RESULTS

In this study, transcriptome sequencing was conducted on both albendazole-sensitive (ABZ-sensitive) and albendazole-resistant (ABZ-resistant) H. contortus strains, with three biological replicates for each group. The analysis of lncRNA in the transcriptomic data revealed that there were 276 differentially expressed lncRNA (DElncRNA) between strains with ABZ-sensitive and ABZ-resistant according to the criteria of |log2Foldchange|≥ 1 and FDR < 0.05. Notably, MSTRG.12969.2 and MSTRG.9827.1 exhibited the most significant upregulation and downregulation, respectively, in the resistant strains. The potential roles of the DElncRNAs included catalytic activity, stimulus response, regulation of drug metabolism, and modulation of the immune response. Moreover, we investigated the interactions between DElncRNAs and other RNAs, specifically MSTRG.12741.1, MSTRG.11848.1, MSTRG.5895.1, and MSTRG.14070.1, involved in regulating drug stimulation through cis/trans/antisense/lncRNA‒miRNA-mRNA interaction networks. This regulation leads to a decrease (or increase) in the expression of relevant genes, consequently enhancing the resistance of H. contortus to albendazole. Furthermore, through comprehensive analysis of competitive endogenous RNAs (ceRNAs) involved in drug resistance-related pathways, such as the mTOR signalling pathway and ABC transporter signalling pathway, the relevance of the MSTRG.2499.1-novel-m0062-3p-HCON_00099610 interaction was identified to mainly involve the regulation of catalytic activity, metabolism, ubiquitination and transcriptional regulation of gene promoters. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) validation indicated that the transcription profiles of six DElncRNAs and six DEmRNAs were consistent with those obtained by RNA-seq.

CONCLUSIONS

The results of the present study allowed us to better understand the changes in the lncRNA expression profile of ABZ-resistant H. contortus. In total, these results suggest that the lncRNAs MSTRG.963.1, MSTRG.12741.1, MSTRG.11848.1 and MSTRG.2499.1 play important roles in the development of ABZ resistance and can serve as promising biomarkers for further study.

Patterns of Equine Small Strongyle Species Infection after Ivermectin Intervention in Thailand: Egg Reappearance Period and Nemabiome Metabarcoding Approach

The indiscriminate use of anthelmintics to control parasitic nematodes in horses has led to the emergence of anthelmintic resistance worldwide. However, there are no data available on using ivermectin for treating strongyle infections within domesticated horses in Thailand. Therefore, this study aimed to use the fecal egg count reduction (FECR) test to determine the strongylid egg reappearance period (ERP). Additionally, the nemabiome metabarcoding approach is incorporated to study patterns of strongyle species infection following ivermectin treatment. The study results indicate that, although ivermectin effectively eliminated adult strongyle parasites within two weeks post-treatment, the ERP was shortened to 6 weeks post-treatment with a mean FECR of 70.4% (95% CI 46.1-84.0). This potentially indicates a recent change in drug performance. In addition, nemabiome metabarcoding revealed that strongyle species have different levels of susceptibility in response to anthelmintic drugs. The reduction in ERP was associated with the early reappearance of specific species, dominated by Cylicostephanus longibursatus and Cylicocyclus nassatus, indicating the lower susceptibility of these species. In contrast, Poteriostomum imparidentatum, Triodontophorus nipponicus, and Triodontophorus serratus were not found post-treatment, indicating the high level of susceptibility of these species. This information is vital for comprehending the factors contributing to the emergence of resistance and for devising strategies to manage and control strongyle infections in horses.