Anthelmintic Resistance In Gastrointestinal Nematodes Research Articles

Anthelmintic resistance and common worm control practices in sheep farms in Flanders, Belgium.

In contrast to many other European countries, no data were available on the presence of anthelmintic resistance in gastrointestinal nematodes in sheep in Belgium. A faecal egg count reduction test was performed in 26 sheep flocks in Flanders, Northern Belgium. Results indicated widespread resistance against benzimidazoles (albendazole, fenbendazole and mebendazole), with treatment failure on all 8 farms investigated. Haemonchus contortus and Teladorsagia circumcincta were the predominant species after treatment failure. Amino acid substitutions associated with benzimidazole resistance were detected at the codon positions 167 (8%) and 200 (92%) of the isotype-1 beta tubulin gene in H. contortus, codon positions 198 (47%) and 200 (43%) in T. circumcincta and position 200 (100%) in T. colubriformis. Resistance against macrocyclic lactones (ivermectin, doramectin and moxidectin) was recorded on 7 out of 20 flocks, mainly in H. contortus and T. circumcincta. Treatment failure was also observed for closantel (in combination with mebendazole) and for monepantel, on one farm each. Trichostrongylus spp. were implicated with resistance against monepantel. A questionnaire survey on farm management and worm control measures indicated that worm control was often not sustainable. Ewes and lambs were treated frequently (on average 2.6 and 3.2 times per year), mostly without weighing. Only few sheep farmers (9%) regularly used faecal egg counts to monitor worm infections. Despite the FECRT showing otherwise, most of the farmers perceived the efficacy of anthelmintics as very good (30%) or good (54%).

Increasing importance of anthelmintic resistance in European livestock: creation and meta-analysis of an open database.

Helminth infections are ubiquitous in grazing ruminant production systems, and are responsible for significant costs and production losses. Anthelmintic Resistance (AR) in parasites is now widespread throughout Europe, although there are still gaps in our knowledge in some regions and countries. AR is a major threat to the sustainability of modern ruminant livestock production, resulting in reduced productivity, compromised animal health and welfare, and increased greenhouse gas emissions through increased parasitism and farm inputs. A better understanding of the extent of AR in Europe is needed to develop and advocate more sustainable parasite control approaches. A database of European published and unpublished AR research on gastrointestinal nematodes (GIN) and liver fluke (Fasciola hepatica) was collated by members of the European COST Action “COMBAR” (Combatting Anthelmintic Resistance in Ruminants), and combined with data from a previous systematic review of AR in GIN. A total of 197 publications on AR in GIN were available for analysis, representing 535 studies in 22 countries and spanning the period 1980–2020. Reports of AR were present throughout the European continent and some reports indicated high within-country prevalence. Heuristic sample size-weighted estimates of European AR prevalence over the whole study period, stratified by anthelmintic class, varied between 0 and 48%. Estimated regional (country) prevalence was highly heterogeneous, ranging between 0% and 100% depending on livestock sector and anthelmintic class, and generally increased with increasing research effort in a country. In the few countries with adequate longitudinal data, there was a tendency towards increasing AR over time for all anthelmintic classes in GIN: aggregated results in sheep and goats since 2010 reveal an average prevalence of resistance to benzimidazoles (BZ) of 86%, macrocyclic lactones except moxidectin (ML) 52%, levamisole (LEV) 48%, and moxidectin (MOX) 21%. All major GIN genera survived treatment in various studies. In cattle, prevalence of AR varied between anthelmintic classes from 0–100% (BZ and ML), 0–17% (LEV) and 0–73% (MOX), and both Cooperia and Ostertagia survived treatment. Suspected AR in F. hepatica was reported in 21 studies spanning 6 countries. For GIN and particularly F. hepatica, there was a bias towards preferential sampling of individual farms with suspected AR, and research effort was biased towards Western Europe and particularly the United Kingdom. Ongoing capture of future results in the live database, efforts to avoid bias in farm recruitment, more accurate tests for AR, and stronger appreciation of the importance of AR among the agricultural industry and policy makers, will support more sophisticated analyses of factors contributing to AR and effective strategies to slow its spread.

Cell grazing and Haemonchus contortus control in sheep: lessons from a two-year study in temperate Western Europe

Managing infections of sheep with anthelmintic resistant gastrointestinal nematodes (GIN) is a major challenge for sheep producers in Western Europe. New methods of grazing management have been poorly explored as a component of an integrated and sustainable control of these parasites. Therefore, the purpose of this study was to evaluate the effect of two different types of grazing systems of sheep (intensive cell grazing versus conventional rotational grazing) on GIN infections over two years in a farm located in a temperate environment of Western France. When considering the whole study, the type of grazing system did not influence significantly the intensity of egg excretions of adult ewes even if the proportion of ewes excreting high numbers of GIN eggs was higher in cell grazing system than in rotational grazing system. The most striking result of this survey was the effect of grazing system on the GIN species composition harbored by ewes and by their lambs: with time, the proportions of H. contortus infections were lower in cell grazing system than in rotational grazing system. In conclusion, the cell grazing system, as implemented in this study, could limit the importance of this highly pathogenic nematode species in sheep.

Anthelmintic resistance in gastrointestinal nematodes in sheep raised under mountain farming conditions in Northern Italy

Anthelmintic resistance (AR) in sheep raised under mountain farming conditions in South Tyrol (Northern Italy) was assessed on eight farms (n=99 animals). A faecal egg count reduction (FECR) test was...

Status of anthelmintic resistance of gastrointestinal nematodes in organized sheep and goat farms

Anthelmintic resistance has become a global problem that threatens livestock production worldwide. The present study was investigated the status of anthelmintic resistance in gastrointestinal (GI) nematodes of small ruminants in two organized sheep and goat farms in two different areas of Bangladesh by fecal egg count reduction test (FECRT) for albendazole, levamisole and ivermectin. In each farms, naturally infected animals were divided into four groups of 10 animals. Fecal samples from each group were collected on day 0 and day 14 of post treatment to measure the eggs per gram of feces (EPG). The fecal samples of each group before and after treatment were also considered for culture to identify resistant parasite. In case of organized sheep farm, the result of FECRT of albendazole was 90.17, 95% confidence with upper and lower limit was 97.82 and 55.68, respectively. The result of FECRT of levamisole and ivermectin was 98.25 and 96.77, 95% confidence with upper and lower limit was 99.79, 85.12 and 99.11, 88.31, respectively. In case of organized goat farm, the result of FECRT of albendazole was 100, 95% confidence with upper and lower limit was 0 and 0, respectively. The result of FECRT of levamisole and ivermectin was 97.99 and 100, 95% confidence with upper and lower limit was 99.59, 90.28 and 0, 0 respectively. The results revealed that gastrointestinal nematodes were found to be resistant to albendazole in organized sheep farm and suspected to be resistant to levamisole and ivermectin. In organized goat farms, the GI nematodes found to be susceptible to all anthelmintics used for this study. Coproculture revealed that Haemonchus spp. were resistant parasite in sheep farm. This seems to be the first documentation of anthelmintic resistance against GI nematodes in organized sheep and goat farms in Bangladesh. Appropriate measures need to be taken to overcome the situation.
 Asian J. Med. Biol. Res. December 2018, 4(4): 378-382

Anthelmintic resistance in gastrointestinal nematodes of goats in an organized farm from Mhow, Madhya Pradesh

Anthelmintic resistance in gastrointestinal nematodes of goats in an organized farm from Mhow, Madhya Pradesh

Anthelmintic resistance in gastrointestinal nematodes of goats in southern Mozambique

Small ruminant production is significantly constrained by gastrointestinal parasites once they cause serious production and economic losses for both small-scale and large-scale farmers in the developing world. The control of helminth parasites is most exclusively based on the use of anthelmintics for the economic production of ruminants. However, the resistance of nematodes to the commonly used groups of anthelmintics represents a threat to the production, particularly for small ruminants. The objective of this study was to assess the efficacy of albendazole, the most frequently used anthelmintic in Gaza and Maputo provinces in the southern region of Mozambique, in gastrointestinal nematodes of goats between November and December, 2016. Eleven goat farms in Gaza (n = 5) and Maputo (n = 6) were surveyed. The faecal egg count reduction test was used to assess the efficacy of the drug. The flocks were considered resistant when the reduction in eggs per gram of faeces was less than 95% and the lower limit of the confidence interval was less than 90%. Resistance to albendazole was detected in 60% (3/5) of the farms in Gaza province and 83.3% (5/6) of the farms in Maputo province. The percentage of faecal egg count reduction varied from 51 to 97% in Maputo and from 0 to 100% in Gaza in the farms surveyed. In pre-treatment coprocultures, Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp. were the predominant nematode species. Post-treatment larval cultures indicated that Haemonchus spp. and, to a lesser extent, Oesophagostomum spp. and Trichostrongylus spp., were resistant to albendazole. This study provided further evidence that anthelmintic resistance of gastrointestinal nematode parasites in goats is currently a problem of great significance in this region of the country and that appropriate measures must be taken to reverse the situation. Key words: Albendazole, efficacy, gastrointestinal parasites, small ruminants, Mozambique.

Utilization of composite fecal samples for detection of anthelmintic resistance in gastrointestinal nematodes of cattle

Recent reports indicate that anthelmintic resistance in gastrointestinal nematodes of cattle is becoming increasingly prevalent worldwide. Presently, the fecal egg count reduction test (FECRT) is the only means available for detection of resistance to anthelmintics in cattle herds at the farm level. However, the FECRT is labor and cost intensive, and consequently is only rarely performed on cattle farms unless for research purposes. If costs could be reduced, cattle producers might be more likely to pursue drug resistance testing on their farms. One approach to reducing the cost of the FECRT, is the use of composite fecal samples for performing fecal egg counts (FEC), rather than conducting FEC on fecal samples from 15 to 20 individual animals. In this study FECRT were performed on 14 groups of cattle using both individual and composite FEC methods To measure how well the results of composite sampling reproduce those of individual sampling, Lin’s Concordance Correlation Coefficient was utilized to describe both the linear relationship between methods and the slope and y-intercept of the line relating the data sets. There was little difference between the approaches with 98% agreement in mean FEC found between methods Mean FEC based on individual counts ranged between 0 and 670.6 eggs per gram of feces, indicating that the results of this study are applicable to a wide range of FEC levels. Standard error of the mean FEC and range of FEC are reported for each group prior to and following treatment to describe the variability of the data set. There was greater than 95% agreement in drug efficacy between individual and composite sampling methods, demonstrating composite sampling is appropriate to evaluate drug efficacy. Notably, for all groups tested the efficacy calculated by composite sampling was within the 95% confidence interval for efficacy calculated using individual sampling. The use of composite samples was shown to reduce the number of FEC required by 79%. These data demonstrate that pooling fecal samples from a group of cattle and then performing repeated FEC on that composite sample yields results very similar to performing individual FEC on those same animals, while substantially reducing the cost of performing a FECRT as compared to individual fecal samples. Furthermore, we have developed suggested methods for using composite samples in a FECRT, provided a cost comparison for this methodology, and described potential issues associated with the use of composite samples that must be considered.

Benzimidazole resistance within red deer, roe deer and sheep populations within a joint habitat in Hungary

The anthelmintic resistance of gastrointestinal nematodes is one of the most important, economic risk factors in grazing ruminant systems, all over the world. We have infinitesimal information about the resistance status of nematodes in deer species. Our aim was to determine the presence of BZ resistance in the generalist worm, Haemonchus contortus in pastured sheep and free ranging red and roe deer by RFLP-PCR method based on the detection Phe200Tyr single nucleotide polymorphism. By investigation of 70 worms from each host species, the homozygous susceptible genotype was the most representative in the red deer (100%), the homozygous resistant genotype was most prevalent in the sheep (68.6%) and moderate in the roe deer (17.1%), while the heterozygous genotype was observed in equal proportion in the sheep and roe deer (28.6%). Our results suggest that overlapping habitats of sheep flocks and roe deer could contribute to the occurrence and spread of resistant allele within wildlife.

Anthelmintic resistance in ruminants: development, diagnostics, and procedures

Anthelmintic resistance of gastrointestinal nematodes in small ruminants, but also in cattle and horses, is now found worldwide. The reason for increasing anthelmintic resistance is, in particular, the extensive use of all the anthelmintic agents available on the market. A non-targeted use leads to the selection of naturally occurring resistance genes within parasite populations. The most practical method for evaluating the efficacy of an anthelmintic is the fecal egg-count reduction test. To reduce the rate of anthelmintic resistance development, the available active substances must be applied less and in a targeted manner. When applying targeted (selective) treatment, part of the herd is left untreated. Therefore, it is necessary to identify the animals that require treatment for health or economic reasons. To decide on anthelmintic treatment, findings can be collected from single animals or from a group of animals in a herd. To determine which groups of animals are to be treated within a herd (targeted treatment), pooled fecal samples (cattle and small ruminants), serum pepsinogen concentration (cattle), or Ostertagia ostertagi antibodies in the bulk milk (cattle) can be analyzed. For individual animal (targeted selective) treatment, criteria including fecal egg count (cattle and small ruminants), conjuctival color as an indicator for infection with Haemonchus contortus (FAMACHA®, small ruminants), body condition in adult animals (small ruminants), weight gain in juvenile animals (cattle and small ruminants), and the consistency of the feces (small ruminants) are used. These decision criteria can also be combined to enhance the informative value. Furthermore, an efficacy test of the anthelmintics used should be performed regularly at the beginning of the pasture season. During the pasture season, a low infection pressure should be maintained by pasture management strategies. The goal of sustainable parasite management is the reduction of anthelmintic treatment while maintaining the productivity and health of the animals and thus a longer effectiveness of the available drugs.

Anthelmintic resistance status of gastrointestinal nematodes of sheep to the single or combined administration of benzimidazoles and closantel in three localities in Mexico

Veterinaria Mexico OA ISSN: 2448-6760 Cite this as: Alcala Canto Y, Sumano Lopez HS, Ocampo Camberos L, Gutierrez L. Anthelmintic resistance status of gastrointestinal nematodes of sheep to the single or combined administration of benzimidazoles and closantel in three localities in Mexico. Veterinaria Mexico OA. 2016;3(4). doi: 10.21753/vmoa.3.4.374 Sheep production requires the constant assessment of parasitic burden and the efficacy of existing treatments for proper management. In this study, the administration of five different treatments was evaluated for the reduction of the percentage of eggs per gram of feces (EPG) shed by gastrointestinal nematodes (GIN) from sheep on three different sheep-breeding farms in Mexico (Texcoco, Estado de Mexico; Hueytamalco, Puebla; and Tlaltizapan de Zapata, Morelos). In these farms, ivermectin and benzimidazole derivatives had been routinely administered for two consecutive years. To determine whether drugs with different pharmacological properties decreased GIN fecal egg excretion, the treatments closantel (CLOS), albendazole (ABZ) and fenbendazole (FBZ) were administered alone and in combinations of CLOS + ABZ and CLOS + FBZ, to five groups of sheep, with an additional untreated control group on each farm (n = 28 per flock). Anthelmintic resistance was determined using Fecal Egg Count Reduction Tests (FECRT) as recommended in the guidelines of the World Association for the Advancement of Veterinary Parasitology. Fecal samples were collected 14 and 21 days after treatment. The anthelmintic resistance status was determined based on the reduction in the fecal egg count arithmetic mean and 95 % confidence limits. According to the FECRT, resistance developed to CLOS, ABZ, FBZ and CLOS + FBZ because the mean percentage of EPG reduction was ≤ 95 % with a lower confidence limit of ≤ 90 %. By contrast, nematode susceptibility was confirmed for the CLOS + ABZ combination, as it reduced the percentage of GIN fecal egg output by 96.46 ± 3.04 % (day 14) and 96.88 ± 3.04 % (day 21). Based on the morphometric identification of larvae, Haemonchus spp., Cooperia spp. and Teladorsagia spp. were the most abundant genera on all farms before the administration of these five treatments. In conclusion, the use of the anthelmintic combination of closantel plus albendazole may reduce the development of anthelmintic resistance in gastrointestinal nematodes. Figure 1. Marginal means ± SD of the percentage reduction in egg count on days 14 and 21 after treatment of sheep on three farms (n = 28 per flock) with fenbendazole (FBZ), closantel (CLOS), albendazole (ABZ), closantel + fenbendazole (CLOS + FBZ) and closantel + albendazole (CLOS + ABZ).

Prevalence of anthelmintic resistance on sheep and goat farms in the mid-Atlantic region and comparison of in vivo and in vitro detection methods

Despite strong economic opportunities and incentives for small ruminant production, their health and productivity are often severely affected by parasitic disease. To combat these effects, most farms administer anthelmintics to their animals at frequent intervals, and without consideration to principles of sustainable integrated parasite management (SIPM). This has led to growing problems caused by the development of drug-resistant populations of gastrointestinal nematodes (GIN) in much of the world, particularly in Haemonchus contortus. The objectives of this research were to characterize levels of anthelmintic resistance on small ruminant farms located in the mid-Atlantic US and to compare the fecal egg count reduction test (FECRT) and larval development assay (LDA) for detecting resistance. To achieve these objectives, the DrenchRite® LDA was used to evaluate resistance status to benzimidazoles, ivermectin, moxidectin, and levamisole on 20 goat and 14 sheep farms in the Mid-Atlantic US over a 2-year period. A FECRT was also conducted on 14 of the same farms and on 2 additional farms in which the LDA was not completed. For the LDA and coprocultures, fecal samples were collected rectally from a minimum of 10 individual animals, pooled, and express-mailed to the University of Georgia for analysis. For the FECRT, albendazole, ivermectin, moxidectin, and/or levamisole were tested on each farm. Animals were allocated randomly based on FAMACHA© scores to 2–5 treatment groups, which included an untreated control group. The number of treatment groups on a farm depended on the number of qualified animals present. Haemonchus contortus was the most common parasite recovered from fecal cultures; the mean level across all farms was 79%. Results of the LDA indicated resistance to benzimidazoles, ivermectin, moxidectin, and levamisole on 100%, 82%, 47%, and 24% of farms, respectively. Multi-drug resistance to all 3 drug classes was detected for H. contortus on 18% of farms (1 sheep and 5 goat farms). Of the 16 farms tested by FECRT, resistance to albendazole was present on 8/10 farms, to ivermectin on 4/4 farms, to moxidectin on 7/9 farms and to levamisole on 2/5 farms tested. Results obtained from the FECRT and the LDA (p=0.51) were similar. The prevalence of resistance found in this study in the mid-Atlantic region of the US is very similar to that reported in an earlier survey of resistance performed in the Southern US, demonstrating that anthelmintic resistance in GIN is a serious problem on small ruminant farms throughout the Eastern US.

Effect of anthelmintic treatment strategy on strongylid nematode species composition in grazing lambs in Scotland

BackgroundRefugia based anthelmintic protocols aim to reduce the rate of development of anthelmintic resistance in gastrointestinal nematodes (GIN). Previous studies have illustrated the impact of different drenching regimes on drug efficacy and animal growth; however, the impact on nematode populations has yet to be characterised within natural infections. This study investigated the changes in species composition of GIN throughout the grazing season, following implementation of four different ivermectin drenching regimes over six years: neo-suppressive monthly treatment (NST), targeted selective treatment (TST), strategic prophylactic treatment (SPT) and treatment upon observation of clinical signs (MT).MethodsLambs were grazed on one of eight replicate paddocks each grazing season following treatment regimes assigned in year 1. Faecal samples were collected fortnightly from all animals and hatched to first stage larvae (L1). DNA was extracted from individual L1 and a multiplex PCR assay targeting the internal transcribed spacer 2 (ITS2) region of Teladorsagia circumcincta, Trichostrongylus spp. and Haemonchus contortus conducted. Other species were identified using species-specific PCR. Worm-naïve tracer lambs were grazed on the paddocks at the start and end of each grazing season and adult worms recovered at post mortem to investigate the parasite population on pasture.ResultsResults showed an overall decrease in species diversity in egg output from the NST group which occurred within a single grazing season and was consistent throughout the experiment. Species diversity was protected over six years in groups implementing TST, SPT and MT treatment regimes, designed to offer refugia. The expected shift in species prevalence throughout the season from Teladorsagia to Trichostrongylus was observed in all but the NST group where only Teladorsagia spp. were recovered from trial lambs by the end of the experiment. Worm burdens indicated the presence of several species at relatively low abundance on pasture in the NST group in 2011. However, these species were not represented in egg output from trial lambs, probably due to the frequent anthelmintic treatment administered throughout the grazing season.ConclusionThe molecular methods utilised here worked well. The comparable results of the three refugia-based treatment regimes suggest that nematode diversity can be maintained using part or whole group treatments if a rich supra-population of parasites are available to re-infect animals post treatment.

Overview of anthelmintic resistance of gastrointestinal nematodes of small ruminants in Brazil

Frequent and inappropriate use of all classes of antiparasitic drugs in small ruminants has led to failures in their effectiveness, culminating in a global problem of anthelmintic resistance. Brazil stands out as one of the world's leaders in publications about anthelmintic resistance, and for having the most numerous reports of this resistance in small ruminants in the Americas. These studies have involved mainly the fecal egg count reduction test (FECRT) and its correlation with field management practices. In vivoeffectiveness testing is conducted in areas where livestock is of greater economic significance, e.g., in the South (sheep) and Northeast (goats), or is important for research and economic centers, such as the Southeast (sheep). The most widely studied species is sheep, for which the widest range of drugs is also evaluated. Despite significant advances achieved in molecular research, laboratory analyses should include knowledge about the reality in the field so that they can become feasible for the producer. Moreover, molecular studies can be underpinned by the analysis of field studies, such as the maintenance of antiparasitic effectiveness over time and the mechanisms involved in this process.

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70–100 calves or more of both genders with ≥200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7–10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7–10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups were effective against multi-drug resistant gastrointestinal nematodes.

First report of multiple anthelmintic resistance in nematodes of sheep in Colombia.

This study aimed to report the presence of parasites resistant to the most used anthelmintic drugs in sheep in Colombia. Four farms (denominated farm 1, 2, 3 and 4) were selected where the animals were not treated with anthelmintics for two months before the trial. Animals with faecal egg count (FEC) above 150 and of different ages were allocated into six groups, each consisting of at least 5 animals. The drugs and dosages used were: ivermectin 1% (0.2 mg/kg), albendazole 25% (5 mg/kg), fenbendazole 10% (5 mg/kg), levamisole 10% (5 mg/kg), and moxidectin 1% (0.2 mg/kg). Anthelmintic efficacy was determined by the FEC reduction test (FECRT) with a second sampling 14 days post-treatment. The efficacy of albendazole and fenbendazole at farm 1 was above 95%, which was different from the others farms. The FECRT indicated the presence of multidrug resistance in the other farms where no tested drugs showed activity higher than 79% (albendazole: 0 to 55%, fenbendazole: 51.4 to 76.6%, ivermectin: 67.3 to 93.1%, levamisole: 0 to 78.1%, and moxidectin: 49.2 to 64.1%).Haemonchus contortus was the predominant (96%) species, followed by a small presence of Trichostrongylus sp. (3%) andCooperia sp. (1%). Therefore, we report for the first time the existence of multiple anthelmintic resistance in gastrointestinal nematodes of sheep in Colombia.

Anthelmintic resistance in gastrointestinal nematodes of dairy cattle in the Macalister Irrigation District of Victoria.

To report anthelmintic resistance in gastrointestinal nematode parasites of cattle on commercial dairy farms in the Macalister Irrigation District of Gippsland, Victoria. Faecal egg count reduction tests (FECRTs) were used to assess anthelmintic resistance on 20 Macalister Irrigation District dairy farms between May 2013 and June 2014. All three currently available anthelmintic classes for cattle nematodes in Australia were tested. Faecal samples were collected 10-14 days post-treatment for individual faecal egg counts (FEC) and larval differentiation. The arithmetic mean FEC for each treatment group was compared with an untreated control post-treatment. Resistance was defined as <95% reduction in FEC, with a lower 95% confidence interval <90% when the mean FEC of the control group, differentiated by genus, was greater than 25 eggs/g. Anthelmintic resistance was present on all 20 dairy farms involved in this study. Resistance to doramectin in at least one species was detected on 15/20 (70%) farms, fenbendazole on 16/20 (80%) farms and levamisole on 5/20 (25%) farms. On three farms, resistance by Ostertagia ostertagi to all three anthelmintic classes was detected. This is the first report of anthelmintic-resistant O. ostertagi on Australian dairy farms. Resistance to all three available anthelmintic classes is of concern, given the high pathogenicity of this species. The study highlights the need for veterinarians and dairy farmers to be aware of the risks posed by anthelmintic resistance.

Anthelmintic resistance in gastrointestinal nematodes from grazing beef cattle in Campeche State, Mexico.

Production of beef cattle is one of the most important economic activities in Mexico. However, anthelmintic resistance (AR) has affected animal productivity. The aim of this study was to determine the presence of AR in gastrointestinal nematodes (GIN) of beef cattle in Candelaria Municipality of Campeche State, Mexico. Sixty-five-month-old beef calves were selected for the faecal egg count reduction test (FECRT) and the inhibition of egg hatch (IEH) assay. These parameters were determined using albendazole (benzimidazole, BZ), ivermectin (IVM, Macrocyclic lactone, ML) and levamisole (LEV, imidazothiazole, IMZ). Allele-specific PCR (AS-PCR) confirmed polymorphisms at codon 200 of isotype 1 of the β-tubulin gene of Haemonchus placei. The results showed 32% IVM toxicity by FECRT, indicating problems of AR in the GIN population. In contrast, BZ and LEV showed 95 and 100% toxicity, respectively, against GIN from infected beef calves. The infective larvae (L3) of Cooperia, Haemonchus and Oesophagostomum were identified before anthelmintic treatment, and Cooperia L3 larvae were identified after treatment with IVM. The IEH assays had lethal dose 50 (LD50) of 187nM to BZ, confirming the ovicidal effect of BZ. In contrast, the LD50 for LEV and IVM were 3.3 and 0.4mM, respectively. The results obtained by AS-PCR confirmed two DNA fragments of 250 and 550bp, corresponding to the resistant and susceptible alleles in the H. placei population. The nematode Cooperia showed AR against IVM, while the toxicity effect of BZ against GIN with both FECRT and IEH was confirmed.

Widespread anthelmintic resistance in European farmed ruminants: a systematic review

digitalData = {"site":{"ip":"192.126.217.197","environment":"LIVE","website":"bvajournals.onlinelibrary.wiley.com","websiteCode":"bvajournals","serverDate":"2022-09-23"},"identities":[{"type":"SmartGroupUser","uuid":"b238ab85-6bb4-49e4-84ca-a0d9f3ee5a35"},{"type":"SmartGroupUser","uuid":"eabce89b-65c2-4a09-ab7c-bd2b3fea2f10"},{"type":"RegionUser","uuid":"3c5060a1-6620-438f-862b-902a4d4cd4ac"},{"type":"RegionUser","uuid":"86f8379b-60ef-449d-b10a-a547ff2452af"},{"type":"SmartGroupUser","uuid":"a86d27d2-6bcd-4b94-bca5-fe16f4882855"},{"type":"SmartGroupUser","uuid":"da88d808-3f7b-4bde-9210-10862b6d121b"},{"type":"SmartGroupUser","uuid":"8c72a733-117a-4bc9-a682-13475f13e6a3"},{"type":"SmartGroupUser","uuid":"756fc162-8722-461f-a077-ebffec4f4fae"},{"type":"SmartGroupUser","uuid":"cf9c85b9-7f3b-4309-aeaa-c41669cabe3b"},{"type":"SmartGroupUser","uuid":"db8b8d10-1aed-4809-b3ee-70938c569014"},{"type":"SmartGroupUser","uuid":"cdce41c2-a8de-4a64-a4d9-a85caaaa2314"},{"type":"SmartGroupUser","uuid":"7a2a316d-5a37-4ccd-afdb-737bfb863a48"},{"type":"SmartGroupUser","uuid":"39f911ce-44b6-4dba-9978-8b2e947a8eb0"},{"type":"SmartGroupUser","uuid":"97587ffd-dcb4-4cb5-9986-a8ce611532bd"},{"type":"SmartGroupUser","uuid":"a46a154d-979f-41ba-b459-fd34df5c071f"},{"type":"SmartGroupUser","uuid":"b7acda8c-ce18-451b-a68d-e14b72f9b5b8"},{"type":"SmartGroupUser","uuid":"055a2bdd-861f-4fa7-bd49-9773db7e0e3e"},{"type":"SmartGroupUser","uuid":"b2dbfe27-ecae-4bb6-bb0d-d75e5caa3762"},{"type":"SmartGroupUser","uuid":"1a6297fb-6679-4882-a4c2-fdd124624edf"},{"type":"SmartGroupUser","uuid":"8032f17e-5050-4fb4-9c40-e1f6875d5c2b"},{"type":"SmartGroupUser","uuid":"ab743440-628f-4964-9216-9983ad3beadf"},{"type":"SmartGroupUser","uuid":"a4187e00-f28e-4754-9a0f-1eb306fb0679"}],"publication":{"item":{"title":"Widespread anthelmintic resistance in European farmed ruminants: a systematic review","doi":"10.1136/vr.102982","access":"no","earliestDate":"2015-05-23","formats":["Cited by","Full text","PDF","References"],"topics":[{"taxonomyUri":"global-subject-codes","topicLabel":"General & Introductory Veterinary Medicine","topicUri":"ve00"},{"taxonomyUri":"global-subject-codes","topicLabel":"VETERINARY MEDICINE","topicUri":"ve"}]},"group":{"title":"","doi":"10.1002/vetr.v176.21","access":"no","volume":"176","issue":"21","coverDate":"2015-05-01","topics":[{"taxonomyUri":"global-subject-codes","topicLabel":"General & Introductory Veterinary Medicine","topicUri":"ve00"},{"taxonomyUri":"global-subject-codes","topicLabel":"VETERINARY MEDICINE","topicUri":"ve"}]},"series":{"title":"Veterinary Record","doi":"10.1002/(ISSN)2042-7670","access":"no","code":"20427670","issn":"0042-4900","eissn":"2042-7670","topics":[{"taxonomyUri":"gpt-sitename","topicLabel":"wly.veterin.med_000119","topicUri":"wly.veterin.med_000119"},{"taxonomyUri":"global-subject-codes","topicLabel":"General & Introductory Veterinary Medicine","topicUri":"ve00"},{"taxonomyUri":"global-subject-codes","topicLabel":"VETERINARY MEDICINE","topicUri":"ve"},{"taxonomyUri":"gpt-zonename","topicLabel":"Veterinary-Record_VETR","topicUri":"veterinary-record_vetr"}]}},"page":{"subPage":"Abstract","page":"Article/Chapter...

Anthelmintic resistance in gastrointestinal nematodes in goats and evaluation of FAMACHA diagnostic marker in Uganda

Gastrointestinal nematodes (GIN) are a challenge to goat production globally causing reduced growth, morbidity and mortality. We report here results of the first nation-wide anthelmintic resistance (AR) study and validation of assessment of clinical anaemia with FAMACHA eye scores in goats in Uganda. From August to December 2012 the efficacy of albendazole (7.5mg/kg), levamisole (10.5mg/kg) and ivermectin (0.3mg/kg) against strongyle nematodes was tested on 33 goat farms in Soroti, Gulu, Mpigi, Mbarara and Ssembabule districts of Uganda. Altogether 497 goats were subjected to a total of 45 different faecal egg count reduction tests (FECRT), each involving 5–20 goats. On one farm all substances were tested. Faecal and blood samples were collected and FAMACHA eye scores evaluated on the day of treatment and 15 days later. A questionnaire survey was conducted on frequency, type and dose of anthelmintics used, farm size and grazing management system. Examination of infective third stage larvae (L3) from pooled faecal cultures demonstrated Haemonchus to be the predominant genus (>75%). Resistance to at least one anthelmintic group was detected on 61% of the 33 farms and in 49% of the 45 test groups. Prevalence of resistance to ivermectin, levamisole and albendazole was respectively 58%, 52% and 38%. Correlation between pre-treatment packed cell volume determinations and FAMACHA scores (r498=−0.89) was significant. Paddock grazing system (Odds ratio 4.9, 95% CI 1.4–17.3) and large farm size of >40 goats (odds ratio 4.4, 95% CI 1.2–16.1) were significant predictors of AR. In all districts, resistance to all three anthelmintics was higher on large-scale goat farms practising mostly paddock grazing. Interestingly, resistance to albendazole, the most commonly used anthelmintic in Uganda, was lower than that to ivermectin and levamisole. We recommend adaptation of FAMACHA to goats to help restrict anthelmintic treatment to heavily infected individuals. This will limit selection pressure and hence delay development of anthelmintic resistance.