Faecal Egg Count Reduction Test Research Articles

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.

93 Evaluating the efficacy of anthelmintics in an upper Midwest horse herd

Abstract Cyathostomins in the gastrointestinal tract are ubiquitous in horses around the world and remain a target in parasite control programs. Resistance to anthelmintics has risen in recent years with widespread resistance to benzimidazoles and pyrantels and emerging resistance to macrocyclic lactones. Thus, investigating the efficacy of anthelmintics in different locations is important to direct future parasite control programs. This 2-yr study evaluated the efficacy of three anthelmintic drugs in a university-owned equine herd in the upper Midwest using fecal egg count reduction tests (FECRT). Additionally, the effect of age group and body condition score (BCS) on fecal egg shedding was evaluated. We hypothesized that drug resistance is present in the parasite population of this equine herd. Fecal egg counts (FEC) of strongelid eggs were determined using the McMaster method. The efficacy of anthelmintics was determined by calculating the percentage of reduction in FEC between d 0 and d 14 post-treatment. Eighteen horses of various breeds were used in the study. The horses were grouped by age (< 10, 10-16, and > 16 yr; n = 6 in each group) and BCS using the Henneke system (5.0-5.5, n = 9; 6.0-6.5., n = 6; and 7.0-8.0, n = 3). In yr 1, horses within age group were randomly assigned to anthelmintic treatment: pyrantel pamoate, fenbendazole, or ivermectin. In yr 2, all horses received ivermectin. Individual FEC were performed on the day of anthelmintic treatment (d 0) using freshly voided feces. FEC were repeated 14 d after treatment. FEC were log transformed before analysis. Efficacy of the anthelmintics were compared using a mixed model ANOVA with repeated measures (SAS 9.4). Results were considered significant when P < 0.05. The FECRT was greater when treated with ivermectin and pyrantel pamoate (94.8 ± 11.6 % and 96.6 ± 14.3 %, respectively) compared with fenbendazole (54.4 ± 10.8 %; P < 0.05). The FECRT increased from 54.4% when treated with fenbendazole to 100% when the same horses were treated with ivermectin (P < 0.05). Age tended to affect egg shedding in horses (P = 0.0548). Young horses (< 10 yr) had a greater FEC compared with older horses (>16 yr; P < 0.05) but were not different from horses aged 10 to 16 yr (P > 0.05). There was no effect of BCS on strongelid egg shedding in this study (P = 0.9468). These results indicate the efficacy was within the expected range with no signs of resistance to pyrantel pamoate (93.3 to 100% reduction). There was evidence of emerging resistance to ivermectin (70.4 to 100% reduction) and significant resistance to fenbendazole (0 to 71.5% reduction) in the cyathostomin population in this horse herd. The findings of this study agree with previous research demonstrating resistance to anthelmintics. These results highlight the importance of designing improved parasite control programs to limit the spread of drug resistance with the ultimate goal of improving overall health of the horse.

Influence of fasting on the efficacy of anthelminthics in naturally infected sheep

The aim of this study was to verify the effect of fasting on the anti-helminthic efficiency of ivermectin-albendazole-levamisole (IAL) combination (first stage) and the closantel and albendazole (second stage) in sheep naturally infected with gastrointestinal nematodes. To this end, fecal samples from young (4 to 6 months), male and female sheep were evaluated seven and 14 days after the treatments, using the Egg count Per Gram of feces (EPG) and the Fecal Egg Count Reduction Test (FECRT). In the first stage of the experiment, the mean EPG of the animals treated and fasted beforehand was lower than the mean EPG of the animals treated, but not fasted 14 days after treatment. Moreover, the group of fasted animals exhibited a better reduction in fecal egg count rate. In the second stage, there was no significant decrease in the mean EPG of the animals in any group (closantel and albendazole) and the efficiency calculated by FECRT was low for the closantel group and zero for the albendazole group. However, the decrease in EPG in animals treated with closantel after fasting was 326.8% greater than the decrease in EPG in animals treated without prior fasting. It was evident that fasting had a positive influence on the reduction of the genera Haemonchus, Cooperia, Trichostrongylus and Oesophagostomum in the animals treated with closantel. The anthelminthic effect of closantel, albendazole and ivermectin-albendazole-levamisole (IAL) combination in sheep was significantly enhanced by previous fasting. Therefore, it is strongly recommended to withhold solid food for a minimum of 12 hours before administering these treatments.

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 EPG 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.

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

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. 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: 500mgkg-1 body weight (bw), 1000mgkg-1 bw, and 2000mgkg-1 bw. In vitro, all the tested concentrations of S.costus (25mg/ml, 50mg/ml, and 100mg/ml) showeda 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 24h 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 500mgkg-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 2000mgkg-1bw showed the highest anthelmintic activity by inducing 83.10% FECR and 76.47% WCR. 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.

Resistance of Gastrointestinal Nematodes to Anthelmintics in Sheep Production in Zimbabwe

Introduction: Sheep play a crucial role in enhancing the socio-economic welfare of individuals in numerous nations. Within sub-Saharan Africa, productivity levels are hindered by various factors, such as prevalent diseases, inadequate nutrition, climate variations, predators, severe weather, as well as infestations of both external and internal parasites. The purpose of the present study was to assess the extent of anthelmintic resistance (AR) observed on a sheep farm operating for commercial purposes in Zimbabwe. Materials and methods: Forty female weaner Dorper sheep, averaging 43 kg in body weight, were selected from Ballineety commercial sheep farm in Mashonaland Central, Zimbabwe. These sheep were then divided into four groups of ten each, receiving different treatments including ivermectin, albendazole, levamisole, and no treatment as a control. Each treatment was administered according to the manufacturer’s recommendations. Pre-treatment faecal samples (day zero) and post-treatment (day 14) were collected and subjected to the Faecal Egg Count Reduction Test (FECRT). Anthelminthic resistance was suggested (AR) by the presence of faecal eggs after treatment. Results: All the drugs indicated a decrease in egg counts by less than 90%. The effectiveness of ivermectin, albendazole, and levamisole was measured at 58.5%, 70.1%, and 85.8% respectively. These findings indicate that nematodes have developed resistance to all treatments. The larval cultures of the samples before and after treatment indicated a significant presence of Haemonchus spp. in the pooled samples. In contrast, the quantities of Trichostrongylus spp. and Oesophagostomum spp. were low but present in all treatments. Cooperia spp. was recovered in post-treatment larval cultures of groups that received anthelmintic. The present study reports lower-than-expected efficacy for ivermectin, albendazole, and levamisole based on the reduction of egg excreted post-treatment. Conclusion: A common worms population in sheep are AR in the current study area. Therefore, comprehensive nematode management programs along with complementary eradication strategies are essential for sustainable sheep production.

A SURVEY OF ANTHELMINTIC EFFICACY IN DAIRY GOAT FARMS IN SOUTH-EAST FRANCE

Goat’s milk production is an important activity in France. Gastrointestinal nematodes (GIN) remain a main threat for grazing goats, usually controlled using anthelmintic drugs (AH). However, 1) eprinomectin (EPN) is the sole molecule yet available without withdrawal time for milk in France; 2) nematodes AH resistances increase dramatically. First, a survey was performed on 13 farms in the Auvergne-Rhône-Alpes (AURA) region to evaluate the efficacy of 2 AH authorized for dairy goats: a benzimidazole (BZ) and a macrocyclic lactone (EPN pour-on). Fecal Egg Count Reduction Tests (FECRT) were carried out using 3 groups of 10 goats per farm: a control group, one treated with BZ (oxfendazole) and one treated with EPN. The results indicate a resistance to BZ in 11 out of 13 farms (84.6%) and a lack of efficacy for EPN pour-on in at least 10 farms (76.9%). Secondly, EPN was given orally or subcutaneously in 4 farms of the previous trial showing a lack of efficacy to EPN pour-on. A resistance to EPN was confirmed in 3 out of 4 farms. Although based on a few farms, these results confirm the high prevalence of resistance of GIN to BZ in dairy goat farms. They also highlight a high level of resistance to EPN and the lack of efficacy of EPN when used pour-on. Given the level of resistance to marketed drugs, there is an urgent need to explore alternative options to AH to prepare integrated, sustainable control of GIN.

58 United States Department of Agriculture National Animal Health Monitoring System Goat 2019 study: Distribution of gastrointestinal nematodes

Abstract One objective of the United States Department of Agriculture National Animal Health Monitoring System Goat 2019 study was to describe practices producers use to control gastrointestinal nematodes (GIN) and reduce anthelmintic resistance through the examination of anthelmintic treatment efficacy via fecal egg count reduction tests and fecal cultures. The fecal cultures were used to determine what GIN were present across the areas of the US included in the study (September 2019-April 2020). Bulk cultures were processed from 318 operations in 24 states and results were consolidated into 4 regions: Northwest (3 states, 34 operations), Northeast (9 states, 89 operations), Southeast (9 states, 132 operations) and Southwest (3 states, 63 operations). GIN identification included Haemonchus, Trichostrongylus, Teladorsagia, Oesophagostomumand Nematodirus. In addition to GIN, lungworm presence was also noted. Haemonchus were found on 18.6% of the operations (Northwest, 27.0%; Northeast, 13.1%; Southeast, 15.9% and Southwest, 29.2%). Trichostrongylus were found on 97.2% of the operations (Northwest, 100%; Northeast, 98%; Southeast, 97.0% and Southwest, 95.7%). Teladorsagia were found on 80.3% of the operations (Northwest, 97.1%; Northeast, 71.6%; Southeast, 88.6% and Southwest (75.7%). Oesophagostomum were found on 38.2% of the operations (Northwest, 73.1%; Northeast, 39.6%, Southeast, 46.4% and Southwest, 15.5%). Nematodiruswere found on 7% of the operations (Northwest, 7%; Northeast, 5.2%, Southeast, 20.8% and Southwest, 0%). Lungworms were found on 35.4% of the operations (Northwest, 69.1%; Northeast, 52.2%, Southeast, 33.4% and Southwest, 8.3%). Due to sampling logistics, fecal collection was conducted during autumn through early spring which may have influenced number of more pathogenic GIN. This study provided valuable insight into regional prevalence of GIN in goats. In depth analyses continues and will be forthcoming.

109 Effectiveness of Fenbendazole in growing Quarter Horses using the Quantitative Modified Wisconsin Technique

Abstract Anthelmintics are commonly used in the equine industry to reduce parasite load, but there is a growing concern about anthelmintic resistance, especially in young horses where there is limited information available. Twenty-four, 2-yr-old Quarter Horses (825 ± 21 d of age, initial BW 409 ± 6 kg, 12 fillies and 12 geldings) originating from a single herd were used in a 42-d study to investigate the effectiveness of a commercial anthelmintic (fenbendazole) on fecal egg counts (FEC), hypothesizing that there would be a decrease in FEC following anthelmintic administration. Horses were housed individually (3.7m × 11m) and offered ad libitum Coastal Bermudagrass hay and water and fed a pelleted concentrate offered at 0.75% (as-fed) of their BW. During the 42-d study, BW was obtained and BCS were assigned in 21-d intervals. Fenbendazole was administered orally on d 0 and 14 dosed on BW per manufacturer label. Fresh fecal samples were collected on d 0 and 14, before anthelmintic administration, and on d 28 and 42. Fecal egg floats were conducted using the Modified Wisconsin Method, and eggs per gram (EPG) were determined in duplicate. A fecal egg count reduction test (FECRT) was calculated, beginning on d 14. Outliers were determined as values ± 2 standard deviations of the mean, and data were analyzed using PROC MIXED of SAS (v9.4) with the main effect of time. Horses increased in BW (P ≤ 0.01) over time, but BCS did not change (P = 0.25). Mean FEC increased over time (P ≤ 0.01), beginning on d 14, and remained increased to d 42 compared to baseline. However, there was a trend (P = 0.07) for mean FEC to be less on d 42 (189.70 ± 29 EPG) when compared with d 14 (251 ± 28 EPG). The calculated reduction of FEC were below the targeted 95% or greater and included d 14 (1.04%), d 28 (35%), and d 42 (41%). The increased shedding of eggs did not negatively impact BW or BCS. However, we reject the hypothesis since FEC increased following anthelmintic treatment, indicating the need for consistent monitoring of anthelmintic efficacy in young horses.

Relative egg extraction efficiencies of manual and automated fecal egg count methods in equines.

The World Association for the Advancement of Veterinary Parasitology recently released new recommendations for the design of fecal egg count (FEC) reduction tests for livestock. These provide suggestions as to the number of animals to be sampled and the minimum number of eggs that must be counted to produce statistically meaningful results. One of the considerations for study design is the multiplication factor of the FEC method to be used; methods with lower multiplication factors require fewer animals to be sampled because they are presumed to count more eggs per test. However, multiplication factor is not the sole determinant of the number of eggs counted by any given method, since different techniques use very different sample extraction methodologies that could affect the number of eggs detected beyond just the amount of feces examined. In this light, we compared three commonly used manual FEC methods (mini-FLOTAC, McMaster and Wisconsin) and two automated methods (Imagyst and Parasight All-in-One) with respect to how many equine strongylid and ascarid eggs they counted in the same samples. McMaster and mini-FLOTAC (multiplication factors of 25x and 5x, respectively) produced the most accurate results of the methods tested but mini-FLOTAC counted approximately 5-times more eggs than McMaster. However, Wisconsin and Parasight (multiplication factor = 1x) counted 3-times more ova than mini-FLOTAC, which was less than the 5-fold difference in their multiplication factors. As a result, these tests perform with multiplication factors more akin to 1.6x relative to mini-FLOTAC. Imagyst, due to its unique sample preparation methodology, does not have a traditional multiplication factor but performed similarly to McMaster with respect to egg recovery.

The first report of triple anthelmintic resistance on a French Thoroughbred stud farm

This study assessed the anthelmintic resistance in strongylid nematodes against commonly used anthelmintic (AH) drugs in a French galloping racehorse stud farm from March to December 2023. Faecal egg count reduction tests (FECRTs) were conducted in three different groups of Thoroughbred yearlings (a group of 6 males, a group of 13 females and a group of 8 females and 3 males) following the new World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines. The efficacy of fenbendazole was tested in two groups once during the monitoring period (in March), the efficacy of ivermectin in 3 groups twice (in March–April and in November–December) and the efficacy of pyrantel in one group once (in May–June). For each FECRT, the 90% confidence interval of the percentage faecal egg count reduction was calculated using the hybrid Frequentist/Bayesian analysis method. The resistance in strongylids was observed to fenbendazole, pyrantel and ivermectin in all the groups in which these drugs were tested. The number of animals in each group was sufficient to reach ≥80% power for the resistance test. The results highlight the first case of triple AH resistance in strongylids in France. Further studies involving more farms and equids are required to assess the prevalence of AH resistance in France and refine recommendations for owners.

The proof is in the poo-ding: Benefits of the longitudinal molecular surveillance of drug resistance demonstrated in a New South Wales cattle herd

Our understanding of anthelmintic resistance in the gastrointestinal nematodes of Australian cattle relies exclusively on small-scale phenotypic reports utilising traditional faecal egg count reduction tests. This approach is not readily scalable to establish the national prevalence of resistance, nor is it conducive of routine longitudinal surveillance for the emergence of resistance in its early stages. This study introduces the benefits of applying mixed amplicon metabarcoding longitudinally for timely and cost-efficient molecular surveillance of multiple anthelmintic resistance mutations, as they emerge on farms. Using opportunistically collected faecal samples from a cattle herd in central west New South Wales (2019–2023), we detected the early emergence of Haemonchus spp. levamisole-resistant S168T shortly after levamisole introduction, while benzimidazole-resistant allele frequencies remained constant. Additionally, we observed the possible spill-over of resistant Haemonchus contortus from sheep, along with variations in faecal burdens and species diversity influenced by climate stochasticity and host immunity. This study emphasises the power of molecular diagnostics for farm-level anthelmintic resistance management, providing essential evidence to support its integration into routine surveillance programmes.

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.

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.

Pyrantel resistance in canine hookworms in Queensland, Australia

Hookworms are the most common intestinal nematode parasites of dogs in Australia. The control of these parasites relies mostly on regular deworming with anthelmintics, with pyrantel-based dewormers being a relatively low cost and readily-available option for dog owners. Pyrantel resistance in canine hookworms in Australia was first reported in 2007, however pyrantel-based dewormers are still used against hookworm infection in dogs across Australia. The present study was conducted to evaluate the efficacy of pyrantel against hookworms infecting dogs housed in a shelter facility in Southeast Queensland which receives rescued or surrendered animals from greyhound rescue centres and dog shelters across this region. A total of 10 dogs were examined using the faecal egg count reduction test (FECRT). There was no reduction in FEC in any of the dogs following pyrantel treatment, with drug efficacies ranging from −0.9% to −283.3%. Given that these dogs originated from various sites across Southeast Queensland, the present study suggests that pyrantel resistance is widespread in this region, and hence this anthelmintic may not be a useful option for treatment of hookworm infections in dogs.

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 5:00-6:00h AM to the following day at 1:00-2:00h 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.

Machine learning prediction of multiple anthelmintic resistance and gastrointestinal nematode control in sheep flocks.

The high prevalence of Haemonchus contortus and its anthelmintic resistance have affected sheep production worldwide. Machine learning approaches are able to investigate the complex relationships among the factors involved in resistance. Classification trees were built to predict multidrug resistance from 36 management practices in 27 sheep flocks. Resistance to five anthelmintics was assessed using a fecal egg count reduction test (FECRT), and 20 flocks with FECRT < 80% for four or five anthelmintics were considered resistant. The data were randomly split into training (75%) and test (25%) sets, resampled 1,000 times, and the classification trees were generated for the training data. Of the 1,000 trees, 24 (2.4%) showed 100% accuracy, sensitivity, and specificity in predicting a flock as resistant or susceptible for the test data. Forage species was a split common to all 24 trees, and the most frequent trees (12/24) were split by forage species, grazing pasture area, and fecal examination. The farming system, Suffolk sheep breed, and anthelmintic choice criteria were practices highlighted in the other trees. These management practices can be used to predict the anthelmintic resistance status and guide measures for gastrointestinal nematode control in sheep flocks.

In vitro and in vivo anthelmintic response of the seeds of Amomum subulatum roxb and Vitex negundo.

The current study was designed to check the anthelmintic activities of some local plants. Seeds of Amomum (A.) subulatum and Vitex (V.) negundo in different solvents were subjected to in vitro (adult motility assay; AMA and egg hatch assay; EHA) and in vivo (faecal egg count reduction test; FECRT) anthelmintic activity testing protocols using Haemonchus (H.) contortus as an experimental model. The results of AMA, EHA, and FECRT were statistically analysed through linear regression and Duncan multiple range test. In AMA test, at 50 mg mL-1 concentration, the percent mortality of H. contortus was higher in A. subulatum than V. negundo, whereas, in EHA test, A. subulatum was proven better ovicidal (LC50=14.2 µg mL-1) than V. negundo (LC50= 65.7405 µg mL-1). The FECRT also indicated the better efficacy of A. subulatum than V. negundo against natural infection of gastrointestinal (GI) parasites. The crude powder of plants used in this study showed 29.6% to 57.7% anthelmintic. The reduction rate was found higher for A. subulatum (3 g kg-1) as compared to V. negundo (7 g kg-1). Reagrding efficacy analysis of solvents used for plants extract, ethyl acetate and chloroform were found better in increasing ovicidal activity in adult worms (in vitro testing), whereas, the crude aqueous methanol was found better than the crude powders in in vivo testing. It will be beneficial to document the indigenous knowledge to standard scientific procedures for their validation. This study will help to motivate the farmers to make a better choice of cultivation of the indigenous plants because of their varying efficacies as an alternative preventive approach against the GI parasitic infections.

The first report of macrocyclic lactone resistant Dictyocaulus viviparus in the UK.

Abstract Background: The bovine lungworm Dictyocaulus viviparus negatively impacts bovine health and leads to substantial economic losses. Lungworm infections can be difficult to manage due to the unpredictable and severe nature of clinical outbreaks. Despite widespread use of long-acting macrocyclic lactones in grazing cattle in the UK, there have been no confirmed reports of resistant lungworm to date, with only one case of anthelmintic resistant lungworm confirmed worldwide. Methods: Lungworm Baermann filtrations were conducted on first season grazing dairy calves as part of a wider study investigating anthelmintic resistance in gastrointestinal nematodes in Scotland using the faecal egg count reduction test. Results: Clinical signs and significant numbers of lungworm larvae in faeces were observed post-treatment with either ivermectin or moxidectin. Resistant gastrointestinal nematode populations were also detected in both treatment groups. Conclusion: This short report describes the first evidence of macrocyclic lactone resistant D. viviparus in the UK.

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.