Epidemiology and Multidrug Resistance of Strongyle Nematodes in Ordos Merino Sheep

Abstract Background: Regular whole-flock treatments and long-term repeated use of similar anthelmintics has led to the development of anthelmintic resistance and widespread epidemic of sheep nematodiasis. The current work was carried out to understand the prevalence of gastrointestinal nematodes in Ordos merino sheep and to evaluate the efficacy of currently used anthelmintics. Results: A total of 4014 fresh fecal samples were collected from sheep from March 2017 to April 2019 and fecal nematode eggs were qualitatively and quantitatively analyzed for understanding the prevalence of sheep nematodiasis. The anthelmintic efficacy of currently used drugs was evaluated in naturally infected sheep. The gastrointestinal nematode infection was serious in Ordos merino sheep. The infection rates of nematodes in three consecutive years were 84.3%, 36.9%, and 42.3%, respectively. The Hemonchus contortus and Nematodirus sp. were the dominantly infected species with the infection rates of 84.3% and 65.6% in 2017. Moreover, these species were acquired highly resistance to the Ivermectin, Doramectin, Albendazole and Levamisole. The percentages of FERC were 6.9%, 1.7%, 3.5% and 79.0%, respectively, following single administration. However, Nitroxynil and Closantel showed a strong anthelmintic efficacy on popular dominant species Haemonchus contortus and some other nematodes, while almost no effect on Nematodirus sp. Conclusions: The prevalence of gastrointestinal nematodes in Ordos merino sheep and their resistance to commonly used anthelmintics were comprehensively understood, and the high efficacy drugs on predominant species were screened out. The results will pay a good foundation for developing of reasonable drug use.

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Epidemiology and Multidrug Resistance of Strongyle Nematodes in Ordos Merino Sheep

10.21203/rs.3.rs-39021/v2 ◽

2020 ◽

Author(s):

Ledege Eye ◽

Jiya Wuen ◽

Xiuling He ◽

Buhe Buyin ◽

Ying Hai ◽

...

Keyword(s):

Haemonchus Contortus ◽

Anthelmintic Resistance ◽

Severe Infection ◽

Nematode Species ◽

Gastrointestinal Nematodes ◽

Infection Rates ◽

Merino Sheep ◽

Predominant Species ◽

Anthelmintic Efficacy ◽

Nematode Eggs

Abstract Background: Regular whole-flock treatments and long-term use of similar anthelmintics have led to the development of anthelmintic resistance and widespread epidemics of nematodiasis in sheep. This study was performed to understand the prevalence of gastrointestinal nematodes in Ordos Merino sheep and evaluate the efficacy of currently used anthelmintics. Results: Between March 2017 and April 2019, a total of 4014 fresh fecal samples were collected from sheep, and fecal nematode eggs were qualitatively and quantitatively analyzed to understand the prevalence of sheep nematodiasis. The anthelmintic efficacy of currently used drugs was evaluated in naturally infected sheep. Severe infection by gastrointestinal nematodes was observed in the Ordos Merino sheep. The infection rates of the nematodes in 3 consecutive years were 84.3%, 36.9%, and 42.3%. Haemonchus contortus and Nematodirus sp. were the predominant nematode species, with infection rates of 84.3% and 65.6%, respectively, in 2017. Moreover, these species had acquired high resistance to ivermectin, doramectin, albendazole, and levamisole; the fecal egg count reduction percentages were 6.9%, 1.7%, 3.5%, and 79.0%, respectively, after a single administration. Nitroxynil and closantel showed strong anthelmintic efficacy against the predominant species Haemonchus contortus and other nematodes, but they had almost no effect on Nematodirus sp. Conclusions: The prevalence of gastrointestinal nematodes in Ordos Merino sheep and their resistance to commonly used anthelmintics were comprehensively evaluated, and the drugs with high efficacy against the predominant species were identified. The findings of this study will provide a good foundation for the appropriate use of anthelmintics.

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Multi-species Grazing for Control of Gastrointestinal Nematodes – a Review

Journal of Animal Science ◽

10.1093/jas/skab096.066 ◽

2021 ◽

Vol 99 (Supplement_2) ◽

pp. 36-37

Author(s):

Joan M Burke ◽

James E Miller

Keyword(s):

Anthelmintic Resistance ◽

Small Ruminants ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Copper Tolerance ◽

Resistant Species ◽

Complex Interactions ◽

Teladorsagia Circumcincta ◽

Management Scheme ◽

Time Required

Abstract Multi-species grazing, alternate grazing of cattle with sheep or goats, offers benefits to gastrointestinal nematode (GIN) control as GIN species differ between hosts. In the Southeastern United States, common GIN species of cattle include Cooperia spp., Ostertagia ostertagi, Haemonchus spp., whereas species of sheep and goats are Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp., Cooperia curticei, and Oesophagostomum spp. Anthelmintic resistance is widely prevalent in small ruminants, and is an increasing problem in cattle, but remains less prevalent. Thus, it is recommended to farmers to use a multi-faceted approach of GIN control, including multi-species grazing. Because management differs between cattle and small ruminants in regard to copper tolerance in minerals, predator control and fencing, alternate grazing of species has most commonly been used. Other considerations include age or susceptibility to GIN, as young calves may be vulnerable to GIN, but mature cows often have negligible GIN infection. Similarly, weanling lambs and kids are susceptible, and depending on breed, adults range from highly resistant to susceptible. Research indicates that GIN burden of more resistant animals is less influenced by multi-species grazing, and highly susceptible animals will likely need additional measures of control. The more resistant species used in the multi-species grazing may lend more control to the more susceptible. Some research showed reductions in O. ostertagi, but not C. oncophora in cattle during extended grazing of cattle and sheep, and reductions of H. contortus and T. colubriformis in sheep. However, other research reported similar worm burdens. Weight gains were improved in lambs grazed alternately with cattle in some studies, and most studies showed little benefit to cattle. Little has been published on alternate grazing with cattle and goats. The complex interactions, larger plot sizes needed, and time required to complete experiments limits published studies of this important management scheme.

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PSII-37 Determining the possible anthelmintic properties of allicin and pumpkin seed oil for mitigation of anthelmintic resistance found in gastrointestinal nematodes infecting ruminants

Journal of Animal Science ◽

10.1093/jas/skz258.446 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 217-218

Author(s):

Collin Hayes ◽

Elizabeth Benavides ◽

Malorie Diamond ◽

Trixie L Wetmore ◽

Ken Mix

Keyword(s):

Seed Oil ◽

Anthelmintic Resistance ◽

Small Ruminants ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Current Treatment ◽

Economic Losses ◽

Ovicidal Activity ◽

Pumpkin Seed ◽

Pumpkin Seed Oil

Abstract Anthelmintics are a widely utilized treatment option for gastrointestinal nematodes infecting ruminants. Recently, these parasites have exhibited increasing resistance towards these drugs. Haemonchus controtus, a gastrointestinal nematode commonly found in small ruminants, has developed resistance towards multiple classes of anthelmintics, leading to huge economic losses worldwide. There are few novel drugs currently being developed, but certain plant-derived products have demonstrated anthelmintic properties when administered in various forms to ruminants. By utilizing these plant products, producers have the opportunity to decrease the rate of development of anthelmintic resistance, and prevent eggs from hatching when excreted by infected livestock. Therefore, it is hypothesized that specific plant-derived products will act as ovicidal agents in H. contortus eggs. The objective of this study was to determine the ovicidal activity of allicin (from Allium sativum) and pumpkin seed oil (PSO). H. contortus eggs were extracted from a pooled fecal sample of Boer and Spanish goats naturally infected with H. contortus. The eggs were then exposed to allicin or PSO at different concentrations. Experiments were replicated four times per concentration. To determine ovicidal activity, samples were observed for unhatched eggs and hatched worms for 24 hours. The 1:100 allicin dilution treatment tended (P = 0.053) to inhibit hatching more than the control. Furthermore, any worms that hatched in allicin treatments exhibited limited signs of motility. Pumpkin seed oil does not appear to possess the same ovicidal potency as allicin, but may still have potential as a larvicidal agent. Based on the current results, allicin is a potential ovicidal agent that may be used independently or incorporated with current treatment methods for H. contortus control.

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Modelling the short- and long-term impacts of drenching frequency and targeted selective treatment on the performance of grazing lambs and the emergence of anthelmintic resistance

Parasitology ◽

10.1017/s0031182012002181 ◽

2013 ◽

Vol 140 (6) ◽

pp. 780-791 ◽

Cited By ~ 14

Author(s):

YAN C. S. M. LAURENSON ◽

STEPHEN C. BISHOP ◽

ANDREW B. FORBES ◽

ILIAS KYRIAZAKIS

Keyword(s):

Anthelmintic Resistance ◽

Treatment Strategies ◽

Short Term ◽

Selective Treatment ◽

Resistance Development ◽

Fecal Egg Count ◽

Anthelmintic Efficacy ◽

Total Weight Gain ◽

Short And Long Term

SUMMARYRefugia-based treatment strategies aim to prolong anthelmintic efficacy by maintaining a parasite population unexposed to anthelmintics. Targeted selective treatment (TST) achieves this by treating only animals that will benefit most from treatment, using a determinant criterion (DC). We developed a mathematical model to compare various traits proposed as DC, and investigate impacts of TST and drenching frequency on sheep performance and anthelmintic resistance. Short term, decreasing the proportion of animals drenched reduced benefits of anthelmintic treatment, assessed by empty body weight (EBW), but decreased the rate of anthelmintic resistance development; each consecutive drenching had a reduced impact on average EBW and an increased impact on the rate of anthelmintic resistance emergences. The optimal DC was fecal egg count, maintaining the highest average EBW when reducing the proportion of animals drenched. Long-term, reducing the proportion of animals drenched had little impact on total weight gain benefits, across animals and years, whilst reducing drenching frequency increased it. Decreasing the frequency and proportion of animals drenched were both predicted to increase the duration of anthelmintic efficacy but reduce the total number of drenches administered before resistance was observed. TST and frequency of drenching may lead to different benefits in the short versus long term.

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Phenotypic and genotypic approaches for detection of anthelmintic resistant sheep gastrointestinal nematodes from Brazilian northeast

Revista Brasileira de Parasitologia Veterinária ◽

10.1590/s1984-29612021048 ◽

2021 ◽

Vol 30 (2) ◽

Author(s):

José Vilemar de Araújo-Filho ◽

Wesley Lyeverton Correia Ribeiro ◽

Weibson Paz Pinheiro André ◽

Géssica Soares Cavalcante ◽

Jéssica Maria Leite dos Santos ◽

...

Keyword(s):

Anthelmintic Resistance ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Northeastern Brazil ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Egg Hatch ◽

Fecal Egg Count ◽

Phenotypic Tests ◽

Brazilian Northeast

Abstract The aim of this study was to characterize the anthelmintic resistance (AR) of a sheep gastrointestinal nematode population, named Caucaia, from northeastern Brazil. Phenotypic tests performed were: egg hatch (EHT), larval development (LDT) and fecal egg count reduction (FECRT). Benzimidazoles (BZs) genotypic evaluation was by frequency of single nucleotide polymorphisms (SNPs) F200Y, F167Y and E198A, and for levamisole (LEV), by frequency of resistance alleles of Hco-acr-8 gene. The primers were designed specifically for Haemonchus contortus. Effective concentrations 50% (EC50) for BZs (EHT), and for macrocyclic lactones (MLs) and LEV (LDT) were 1.02 µg/mL, 1.81 ng/mL and 0.04 µg/mL, respectively. Resistance ratios for MLs and LEV were 0.91 and 3.07, respectively. FECRT efficacies of BZs, MLs, monepantel (MPTL) and LEV were 52.4; 87.0; 94.5 and 99.6%, respectively. qPCR for BZs demonstrated resistance allele frequencies of 0%, 26.24% and 69.08% for SNPs E198A, F200Y and F167Y, respectively. For LEV, 54.37% of resistance alleles were found. There was agreement between EHT, FECRT and qPCR for BZs, and agreement between LDT and qPCR for LEV. Thus, based on higher sensitivity of qPCR, and phenotypic evaluation, the Caucaia population was considered resistant to BZs, MLs, LEV and suspect for MPTL.

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Control measures recommended for goat gastrointestinal nematode infections after analysis of infection dynamics in the semiarid region of Brazil

Ciência Rural ◽

10.1590/0103-8478cr20200383 ◽

2020 ◽

Vol 50 (11) ◽

Author(s):

Vanessa Diniz Vieira ◽

Franklin Riet Correa ◽

Vinícius Longo Ribeiro Vilela ◽

Márcia Alves de Medeiros ◽

Jouberdan Aurino Batista ◽

...

Keyword(s):

Rainy Season ◽

Anthelmintic Resistance ◽

Gastrointestinal Nematode ◽

Parasite Load ◽

Gastrointestinal Nematodes ◽

Control Measures ◽

Annual Rainfall ◽

Semiarid Region ◽

Gastrointestinal Helminths ◽

Lactating Goats

ABSTRACT: This study aimed to determine control measures for gastrointestinal nematodes in goats in the northeastern semiarid after analyzing the dynamics of gastrointestinal helminths during the drought, the evolution of the parasitic load after the first rains and the differences in susceptibility between goats of different categories and ages. Five farms were studied from March 2013 to January 2015. Feces were collected from all goats every month, for fecal egg counts (FECs). No treatment was required on any farm during the dry period. In 2013, with annual rainfall of 265-533 mm, treatments were not necessary during the rainy season. However, in 2014, with rainfall of 604-778 mm, treatments were necessary 60-90 days, after the first rains. On three farms, gastrointestinal nematodes showed multiple anthelmintic resistance. The FECs from lactating goats were significantly higher than from dry and young goats. In conclusion, in the Brazilian semi-arid region (Caatinga biome), it is generally unnecessary to treat grazing goats during the dry season. In the rainy season, the parasite load increases 2-3 months after the first rains. In both, the dry and the rainy season, farmers should monitor their herds by means of FEC or another criterion (anemia or submandibular edema), to determine the need to treat.

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The threat of reduced efficacy of anthelmintics against gastrointestinal nematodes in sheep from an area considered anthelmintic resistance-free

Parasites & Vectors ◽

10.1186/s13071-020-04329-2 ◽

2020 ◽

Vol 13 (1) ◽

Cited By ~ 1

Author(s):

Antonio Bosco ◽

Jan Kießler ◽

Alessandra Amadesi ◽

Marian Varady ◽

Barbara Hinney ◽

...

Keyword(s):

Southern Italy ◽

Anthelmintic Resistance ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Minor Role ◽

Macrocyclic Lactones ◽

On Farm ◽

Pooled Samples

Abstract Background The worldwide increased difficulty to combat gastrointestinal nematode (GIN) infection in sheep, due to progressing anthelmintic resistance (AR), calls for an enhanced and standardized implementation of early detection of AR. This study provides a snapshot of the current AR status against benzimidazoles and macrocyclic lactones in southern Italy, generated with standardized techniques. Methods On 10 sheep farms, the efficacy of albendazole (ALB) and either eprinomectin (EPR) or ivermectin (IVM) was evaluated based on the faecal egg count reduction test (FECRT) performed with the Mini-FLOTAC. For each tested drug, 40 sheep were rectally sampled at D0 and sampled again 14 days after the treatment (D14). The FECRT was calculated from individual samples and pooled samples which consist of 5 individual samples. Efficacy was classified as ‘reduced, ‘suspected’ and ‘normal’. Coprocultures were set for D0 and D14 faecal samples of each group. From farms with FECR < 95%, an in vitro egg hatch test (EHT) and a follow-up FECRT using fenbendazole (FBZ) were conducted. Results Based on the FECR, high efficacy (from 95.7% to 100%) was observed for ALB and IVM in eight farms (Farms 3–10). On Farm 1 and Farm 2, the efficacy for the macrocyclic lactones was classified as ‘normal’, but ‘reduced’ efficacy was observed for ALB on Farm 1 (FECR = 75%) and ‘suspected’ efficacy on Farm 2 (FECR = 93.3%) with the predominant GIN genus Trichostrongylus followed by Haemonchus at D14. The FEC results of pooled samples strongly correlated with those of individual samples, for FEC at D0 (rs = 0.984; P < 0.0001) and at D14 (rs = 0.913; P < 0.0001). The classifications of efficacy in Farm 1 (FECR = 86.0%) and Farm 2 (FECR = 93.0%) in the follow-up FECRT with FBZ coincide with the main FECRT trial. The in vitro EHT confirmed AR in both farms (Farm 1: 89%; Farm 2: 74%). Conclusions In regions like southern Italy, where the negative impacts from AR have played a minor role, efficient monitoring of AR is important in order to evaluate potential risks and being able to promptly respond with countermeasures.

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Effects of an algal biomass supplement on the periparturient rise in nematode egg output from ewes and the subsequent effects on their offspring

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200019992 ◽

2007 ◽

Vol 2007 ◽

pp. 96-96

Author(s):

E. Scott-Baird ◽

C. Leifert ◽

S.A. Edwards ◽

G. Butler

Keyword(s):

Anthelmintic Resistance ◽

Late Pregnancy ◽

Long Term Effects ◽

Animal Products ◽

Control Programmes ◽

Nematode Eggs ◽

Parasite Infestation ◽

High Concentrations ◽

Crucial Part

The periparturient rise in nematode eggs at lambing is a crucial part of the epidemiology of nematode infections as it allows a large number of infective larvae to be present in the pastures when the lamb is young and most immunologically naïve. With a rapidly rising level of anthelmintic resistance and increasing public concern over drug residues remaining in animal products, it is necessary to achieve more long-term, sustainable nematode control programmes. Some plant products could provide alternatives or adjuncts to conventional control with anthelmintics and ease the selection pressure for anthelmintic resistance. The polyunsaturated fatty acid, docosahexaenoic acid (DHA), which can be produced in high concentrations by some marine algae, has been shown to modify immune response in many species and decrease the production of proinflammatory cytokines (Calder, 2001). This action could reduce inflammation in the gut in response to parasite infestation and reduce the extent of associated hypophagia. The objective of this study was to investigate the long term effects of providing an algal DHA dietary supplement in late pregnancy, on the periparturient rise and the resulting effects on the infection levels and production consequences for their lambs.

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

Veterinary Record Open ◽

10.1136/vetreco-2018-000332 ◽

2019 ◽

Vol 6 (1) ◽

pp. e000332 ◽

Cited By ~ 1

Author(s):

Christian Lambertz ◽

Ioanna Poulopoulou ◽

Kunlayaphat Wuthijaree ◽

Matthias Gauly

Keyword(s):

Macrocyclic Lactone ◽

Anthelmintic Resistance ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Northern Italy ◽

Controlled Conditions ◽

Oral Formulations ◽

Wide Range ◽

High Prevalence ◽

Faecal Egg Count

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 done after routine anthelmintic treatments. Furthermore, on 27 farms (n=306 animals), a FECR test was conducted after oral formulations of a macrocyclic lactone (ML), benzimidazole (BZ) (partly in combination with salicylanilide (SA)) or a combination of imidazothiazole and SA were applied under controlled conditions on the same farm. Following routine treatments, three of five ML-treated flocks showed an adequate efficacy, while the other two reached a FECR of only around 75 per cent. A wide range of gastrointestinal nematode genera were identified in one flock following the treatment. From the three BZ-treated flocks, only one showed an adequate FECR, both other farms reached 68 per cent and 84 per cent, respectively. Under controlled conditions, FECR ranged between 77 per cent and 81 per cent indicating AR for all the applied anthelmintics. Trichostrongylus species, Teladorsagia species and Haemonchus species were identified after ML treatment, Teladorsagia species after BZ treatment and Trichostrongylus species and Haemonchus species after combined BZ and SA application. Taking into consideration that underdosing might have affected results of the routine treatments, a high prevalence of AR was found in sheep under mountain farming conditions.

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High Predatory Capacity of a Novel Arthrobotrys oligospora Variety on the Ovine Gastrointestinal Nematode Haemonchus contortus (Rhabditomorpha: Trichostrongylidae)

Pathogens ◽

10.3390/pathogens10070815 ◽

2021 ◽

Vol 10 (7) ◽

pp. 815

Author(s):

Fabián Arroyo-Balán ◽

Fidel Landeros-Jaime ◽

Roberto González-Garduño ◽

Cristiana Cazapal-Monteiro ◽

Maria Sol Arias-Vázquez ◽

...

Keyword(s):

Haemonchus Contortus ◽

Anthelmintic Resistance ◽

Three Dimensional ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Control Group ◽

Arthrobotrys Oligospora ◽

Aerial Hyphae ◽

Conidia Production ◽

Predatory Capacity

With the worldwide development of anthelmintic resistance, new alternative approaches for controlling gastrointestinal nematodes in sheep are urgently required. In this work, we identified and characterized native nematode-trapping fungi. We collected seven isolates of fungi with the capacity to form adhesive, three-dimensional networks as the main mechanism to capture, kill, and consume nematodes. The nematode-trapping fungi were classified into two groups; the first group includes the R2-13 strain, showing faster growth, abundant aerial hyphae, scarce conidia production, bigger conidia, and it formed a clade with Arthrobotrys oligospora sensu stricto. The second comprises the A6, A12, A13, R2-1, R2-6, and R2-14 strains, showing a growth adhering to the culture medium, forming little aerial hyphae, smaller conidia, and these formed a sister clade to A. oligospora. Except for the R2-6 strain, conidia production was induced by light. In all the strains, the predatory capacity against the sheep gastrointestinal nematode Haemonchus contortus was greater than 58% compared with the control group. The A6 and A13 strains were the most active against the infective H. contortus third instar (L3) larvae, with an average capture capacity of 91%. Altogether, our results support evidence for a novel A. oligospora variety with high nematode-trapping activity and promissory in helminthic control.

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