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Jewell N, Swinson V, Hayman C, Martindale L, Brzozowska A, Mitchell S. Laboratory diagnosis of gastrointestinal nematodes in first-grazing-season cattle. Vet Rec 2023; 192:364-366. [PMID: 37288889 DOI: 10.1002/vetr.3020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This focus article has been prepared by Natalie Jewell of the APHA Cattle Expert Group with the assistance of Vanessa Swinson (veterinary lead of the APHA Cattle Expert Group), Claire Hayman, Lucy Martindale and Anna Brzozowska (Surveillance Intelligence Unit), and Siân Mitchell (formerly the APHA's parasitology discipline champion).
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Filipe JAN, Kyriazakis I, McFarland C, Morgan ER. Novel epidemiological model of gastrointestinal nematode infection to assess grazing cattle resilience by integrating host growth, parasite, grass and environmental dynamics. Int J Parasitol 2023; 53:133-155. [PMID: 36706804 DOI: 10.1016/j.ijpara.2022.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 01/26/2023]
Abstract
Gastrointestinal nematode (GIN) infections are ubiquitous and often cause morbidity and reduced performance in livestock. Emerging anthelmintic resistance and increasing change in climate patterns require evaluation of alternatives to traditional treatment and management practices. Mathematical models of parasite transmission between hosts and the environment have contributed towards the design of appropriate control strategies in ruminants, but have yet to account for relationships between climate, infection pressure, immunity, resources, and growth. Here, we develop a new epidemiological model of GIN transmission in a herd of grazing cattle, including host tolerance (body weight and feed intake), parasite burden and acquisition of immunity, together with weather-dependent development of parasite free-living stages, and the influence of grass availability on parasite transmission. Dynamic host, parasite and environmental factors drive a variable rate of transmission. Using literature sources, the model was parametrised for Ostertagia ostertagi, the prevailing pathogenic GIN in grazing cattle populations in temperate climates. Model outputs were validated on published empirical studies from first season grazing cattle in northern Europe. These results show satisfactory qualitative and quantitative performance of the model; they also indicate the model may approximate the dynamics of grazing systems under co-infection by O. ostertagi and Cooperia oncophora, a second GIN species common in cattle. In addition, model behaviour was explored under illustrative anthelmintic treatment strategies, considering impacts on parasitological and performance variables. The model has potential for extension to explore altered infection dynamics as a result of management and climate change, and to optimise treatment strategies accordingly. As the first known mechanistic model to combine parasitic and free-living stages of GIN with host feed-intake and growth, it is well suited to predict complex system responses under non-stationary conditions. We discuss the implications, limitations and extensions of the model, and its potential to assist in the development of sustainable parasite control strategies.
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Affiliation(s)
- J A N Filipe
- Biomathematics & Statistics Scotland, Rowett Institute of Nutrition and Health, University of Aberdeen, AB25 2ZD, UK.
| | - I Kyriazakis
- Institute for Global Food Security, Queen's University Belfast, Biological Sciences, 19, Chlorine Gardens, BT9 5DL, UK
| | - C McFarland
- Institute for Global Food Security, Queen's University Belfast, Biological Sciences, 19, Chlorine Gardens, BT9 5DL, UK
| | - E R Morgan
- Institute for Global Food Security, Queen's University Belfast, Biological Sciences, 19, Chlorine Gardens, BT9 5DL, UK
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Sabatini GA, de Almeida Borges F, Claerebout E, Gianechini LS, Höglund J, Kaplan RM, Lopes WDZ, Mitchell S, Rinaldi L, von Samson-Himmelstjerna G, Steffan P, Woodgate R. Practical guide to the diagnostics of ruminant gastrointestinal nematodes, liver fluke and lungworm infection: interpretation and usability of results. Parasit Vectors 2023; 16:58. [PMID: 36755300 PMCID: PMC9906602 DOI: 10.1186/s13071-023-05680-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/21/2023] [Indexed: 02/10/2023] Open
Abstract
The diagnostics of ruminant parasites remains one of the cornerstones for parasite control best practices. Field veterinarians have several techniques at their disposal (fecal egg count, coproculture, FAMACHA®, plasma pepsinogen, ELISA-Ostertagia, ELISA-Fasciola, Baermann and ELISA-Lungworm) for the identification and/or quantification of gastrointestinal nematodes, lungworms and liver fluke infecting small ruminants and cattle. Each of these diagnostic tools has its own strengths and weaknesses and is more appropriate for a specific production operation and/or age of the animal (young and adults). This review focuses on the usability and interpretation of the results of these diagnostic tools. The most advanced technical information on sampling, storage, advantages and limitations of each tool for different types of production operations and animal categories is provided.
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Affiliation(s)
| | | | | | | | - Johan Höglund
- grid.6341.00000 0000 8578 2742Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | | | - Sian Mitchell
- The former Animal and Plant Health Agency (APHA), Perth, UK
| | - Laura Rinaldi
- grid.4691.a0000 0001 0790 385XUniversity of Naples Federico II, Naples, Italy
| | | | - Pedro Steffan
- Fiel & Steffan Consultores Asociados, Tandil, Argentina
| | - Robert Woodgate
- grid.1010.00000 0004 1936 7304University of Adelaide, Roseworthy, Australia
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Morgan ER, Lanusse C, Rinaldi L, Charlier J, Vercruysse J. Confounding factors affecting faecal egg count reduction as a measure of anthelmintic efficacy. Parasite 2022; 29:20. [PMID: 35389336 PMCID: PMC8988865 DOI: 10.1051/parasite/2022017] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/07/2022] [Indexed: 11/29/2022] Open
Abstract
Increasing anthelmintic resistance (AR) in livestock has stimulated growing efforts to monitor anthelmintic effectiveness (AE) on livestock farms. On-farm assessment of AE relies on measuring the reduction in faecal egg count (FEC) following treatment; and if conducted rigorously, qualifies as a formal FEC reduction test (FECRT) for AR. Substantial research effort has been devoted to designing robust protocols for the FECRT and its statistical interpretation; however, a wide range of factors other than AR can affect FEC reduction on farms. These are not always possible to control, and can affect the outcome and repeatability of AE measurements and confound the on-farm classification of AR using FECRT. This review considers confounders of FEC reduction, focusing on gastrointestinal nematodes of ruminants, including host and parasite physiology and demography; pharmacokinetic variation between drugs, parasites and hosts; and technical performance. Drug formulation and delivery, host condition and diet, and seasonal variation in parasite species composition, can all affect AE and hence observed FEC reduction. Causes of variation in FEC reduction should be attenuated, but this is not always possible. Regular monitoring of AE can indicate a need to improve anthelmintic administration practices, and detect AR early in its progression. Careful interpretation of FEC reduction, however, taking into account possible confounders, is essential before attributing reduced FEC reduction to AR. Understanding of confounders of FEC reduction will complement advances in FECRT design and interpretation to provide measures of anthelmintic efficacy that are both rigorous and accessible.
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Affiliation(s)
- Eric R Morgan
- School of Biological Sciences, Queen's University Belfast, 19, Chlorine Gardens, BT9 5DL Belfast, United Kingdom
| | - Carlos Lanusse
- Laboratorio de Farmacología, Centro de Investigación Veterinaria de Tandil (CIVETAN) (UNCPBA-CICPBA-CONICET), Facultad de Ciencias Veterinarias, UNCPBA, 7000 Tandil, Argentina
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Via Delpino, 1, 80137 Naples, Italy
| | | | - Jozef Vercruysse
- Faculty of Veterinary Medicine, University of Gent, Salisburylaan 133, 9820 Merelbeke, Belgium
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Hildreth MB, McKenzie JB. Epidemiology and Control of Gastrointestinal Nematodes of Cattle in Northern Climates. Vet Clin North Am Food Anim Pract 2020; 36:59-71. [PMID: 32029189 DOI: 10.1016/j.cvfa.2019.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Parasite species infecting cattle throughout northern North American are generally the same as those found throughout North America. Throughout Canada, cattle are primarily infected with Ostertagia ostertagi and Cooperia oncophora, whose larvae survive cold winters within soil of pastures. Overwintering larvae of these species maintain a temporary population of refugia available in spring to grazing cattle. Cattle from northern United States are also infected with Cooperia punctata and Haemonchus placei, whose larvae cannot survive cold winters within pastures. Anthelmintics with persistent activity are used during spring to recover some of these losses; however, anthelmintic resistance limits effectiveness of this strategy.
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Affiliation(s)
- Michael B Hildreth
- Department of Biology and Microbiology, South Dakota State University, SNP 252, Brookings, SD 57007, USA.
| | - John B McKenzie
- Department of Biology and Microbiology, South Dakota State University, SNP 252, Brookings, SD 57007, USA
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Charlier J, Höglund J, Morgan ER, Geldhof P, Vercruysse J, Claerebout E. Biology and Epidemiology of Gastrointestinal Nematodes in Cattle. Vet Clin North Am Food Anim Pract 2020; 36:1-15. [PMID: 32029177 DOI: 10.1016/j.cvfa.2019.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This article reviews the basics of gastrointestinal nematode biology and pathophysiology in cattle and describes how gastrointestinal nematode epidemiology is driven by environmental, host, and farm economic determinants. Adverse effects from gastrointestinal nematodes on their hosts are caused by tissue damage, nutrient absorption, immunopathologic effects, and reduced food intake induced by hormonal changes. Weather and microenvironmental factors influence the development and survival of free-living parasitic stages. A holistic control approach entails the consideration of environmental, immunologic, and socioeconomic aspects of nematode epidemiology and is key for the development and communication of sustainable control strategies.
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Affiliation(s)
| | - Johan Höglund
- Swedish University of Agricultural Sciences, Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Box 7036, Uppsala 75007, Sweden
| | - Eric R Morgan
- Biological Sciences, Queen's University of Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
| | - Peter Geldhof
- Faculty of Veterinary Medicine, Laboratory of Parasitology, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium
| | - Jozef Vercruysse
- Faculty of Veterinary Medicine, Laboratory of Parasitology, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium
| | - Edwin Claerebout
- Faculty of Veterinary Medicine, Laboratory of Parasitology, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium
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Rose Vineer H, Verschave SH, Claerebout E, Vercruysse J, Shaw DJ, Charlier J, Morgan ER. GLOWORM-PARA: a flexible framework to simulate the population dynamics of the parasitic phase of gastrointestinal nematodes infecting grazing livestock. Int J Parasitol 2020; 50:133-144. [PMID: 31981671 DOI: 10.1016/j.ijpara.2019.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 11/22/2019] [Accepted: 11/29/2019] [Indexed: 10/25/2022]
Abstract
Gastrointestinal nematodes are a significant threat to the economic and environmental sustainability of keeping livestock, as adequate control becomes increasingly difficult due to the development of anthelmintic resistance in some systems and climate-driven changes to infection dynamics. To mitigate any negative impacts of climate on gastrointestinal nematode epidemiology and slow anthelmintic resistance development, there is a need to develop effective, targeted control strategies that minimise the unnecessary use of anthelmintic drugs and incorporate alternative strategies such as vaccination and evasive grazing. However, the impacts climate and gastrointestinal nematode epidemiology may have on the optimal control strategy are generally not considered, due to lack of available evidence to drive recommendations. Parasite transmission models can support control strategy evaluation to target field trials, thus reducing the resources and lead-time required to develop evidence-based control recommendations incorporating climate stochasticity. Gastrointestinal nematode population dynamics arising from natural infections have been difficult to replicate and model applications have often focussed on the free-living stages. A flexible framework is presented for the parasitic phase of gastrointestinal nematodes, GLOWORM-PARA, which complements an existing model of the free-living stages, GLOWORM-FL. Longitudinal parasitological data for two species that are of major economic importance in cattle, Ostertagia ostertagi and Cooperia oncophora, were obtained from seven cattle farms in Belgium for model validation. The framework replicated the observed seasonal dynamics of infection in cattle on these farms and overall, there was no evidence of systematic under- or over-prediction of faecal egg counts. However, the model under-predicted the faecal egg counts observed on one farm with very young calves, highlighting potential areas of uncertainty that may need further investigation if the model is to be applied to young livestock. The model could be used to drive further research into alternative parasite control strategies such as vaccine development and novel treatment approaches, and to understand gastrointestinal nematode epidemiology under changing climate and host management.
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Affiliation(s)
- H Rose Vineer
- Veterinary Parasitology and Ecology Group, Bristol Veterinary School, University of Bristol, BS8 1TQ, UK; Cabot Institute, Royal Fort House, University of Bristol, BS8 1UJ, UK; Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Neston, Cheshire CH64 7TE, UK.
| | - S H Verschave
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
| | - E Claerebout
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - J Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - D J Shaw
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
| | - J Charlier
- Kreavet, Hendrik Mertensstraat 17, 9150 Kruibeke, Belgium
| | - E R Morgan
- Veterinary Parasitology and Ecology Group, Bristol Veterinary School, University of Bristol, BS8 1TQ, UK; Cabot Institute, Royal Fort House, University of Bristol, BS8 1UJ, UK; Institute for Global Food Security, Queen's University Belfast, BT9 7BL, UK
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Sauermann CW, Ganesh S, Scott I, Pomroy WE, Leathwick DM. Establishment of Cooperia oncophora in calves. Vet Parasitol 2018; 264:64-68. [PMID: 30503094 DOI: 10.1016/j.vetpar.2018.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/01/2018] [Accepted: 11/01/2018] [Indexed: 10/27/2022]
Abstract
The establishment rate of Cooperia oncophora related to host age and previous infection was investigated in young calves. Calves of similar age were kept on a feed pad and allocated into multiple groups, based on their age and weight. Two groups (each n = 16) received trickle infections with an ivermectin-susceptible C. oncophora isolate of 2000 or 10,000 infective stage larvae per week while another group (n = 16) was kept as an uninfected control. At intervals over a period of 11 months, two animals from each group were challenged with 15,000 infective stage larvae of an ivermectin-resistant isolate, 25 days later orally treated with ivermectin and 5 days after that slaughtered for worm counts. On three occasions additional calves (n = 2), subjected to the high trickle infection rate, received an ivermectin treatment to remove the existing worm burden, prior to challenge as above. Further calves (n = 4) of similar age were introduced at the beginning and the end of the experiment to determine the effect of larval age on establishment rate. The establishment in the two trickle infection groups declined to <10% within the first three months, which was significantly different from the control group. In the animals receiving the high trickle infection, but an anthelmintic treatment before challenge the establishment rate was not significantly different from the controls. Over the duration of the experiment establishment in the control group declined from 53% to <20%, which was similar to the decrease recorded at the beginning and the end of the experiment in the animals to determine the effect of larval age. The findings indicate that an existing C. oncophora burden had a strong effect on the establishment of incoming larvae in the trickle infected groups, but this was not observed if the existing burden was removed before the final challenge. The decline in establishment rate in the control group was attributed to the age of the larvae and not the age of the calves per se.
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Affiliation(s)
| | - Siva Ganesh
- AgResearch Grasslands, Private Bag 11008, Palmerston North, 4442, New Zealand
| | - Ian Scott
- School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - William E Pomroy
- School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Dave M Leathwick
- AgResearch Grasslands, Private Bag 11008, Palmerston North, 4442, New Zealand
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Liu M, Landuyt B, Klaassen H, Geldhof P, Luyten W. Screening of a drug repurposing library with a nematode motility assay identifies promising anthelmintic hits against Cooperia oncophora and other ruminant parasites. Vet Parasitol 2018; 265:15-18. [PMID: 30638515 DOI: 10.1016/j.vetpar.2018.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 11/16/2022]
Abstract
Parasitic nematodes continue to cause significant economic losses in livestock globally. Given the limited number of anthelmintic drugs on the market and the currently increasing drug resistance, there is an urgent need for novel anthelmintics. Most motility assays of anthelmintic activity for parasitic nematodes are laborious and low throughput, and therefore not suitable for screening large compound libraries. Cooperia oncophora accounts for a large proportion of reports on the drug-resistance development of parasites globally. Therefore, using a WMicroTracker instrument, we established a practical, automated and low-cost whole-organism motility assay against exsheathed L3 stages (xL3s) of the ruminant parasite Cooperia oncophora, and screened a repurposing library comprising 2745 molecules. Fourteen known anthelmintics contained in this library were picked up in this blind screen, as well as four novel hits: thonzonium bromide, NH125, physostigmine sulfate, and EVP4593. The four hits were also active against xL3s of Ostertagia ostertagi, Haemonchus contortus and Teladorsagia circumcincta using the same assay. Cytotoxicity testing showed that thonzonium bromide and NH125 (1-Benzyl-3-cetyl-2-methylimidazolium iodide) have significant cytotoxicity. EVP4593 (N(4)-(2-(4-phenoxyphenyl)ethyl)-4,6-quinazolinediamine) demonstrated a potent and broad anthelmintic activity, and a high selectivity index. Moreover, given its novel and unexplored chemical scaffold for anthelmintic activity, EVP4593 is an interesting anthelmintic hit for further optimization.
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Affiliation(s)
- Maoxuan Liu
- Center of antibody drug, Institute of biomedicine and biotechnology, Shenzhen institutes of advanced technology, Chinese Academy of Science, Shenzhen, 518055, China; Department of Biology, Animal Physiology and Neurobiology Section, KU Leuven, Naamsestraat 59, box 2465, 3000 Leuven, Belgium; Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Herestraat 49, box 921, 3000 Leuven, Belgium.
| | - Bart Landuyt
- Department of Biology, Animal Physiology and Neurobiology Section, KU Leuven, Naamsestraat 59, box 2465, 3000 Leuven, Belgium
| | - Hugo Klaassen
- Cistim Leuven vzw, Bioincubator 2, Gaston Geenslaan 2, 3001 Leuven, Belgium
| | - Peter Geldhof
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke B-9820, Belgium
| | - Walter Luyten
- Department of Biology, Animal Physiology and Neurobiology Section, KU Leuven, Naamsestraat 59, box 2465, 3000 Leuven, Belgium
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Sauermann CW, Leathwick DM. A climate-driven model for the dynamics of the free-living stages of Cooperia oncophora. Vet Parasitol 2018; 255:83-90. [DOI: 10.1016/j.vetpar.2018.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 03/28/2018] [Accepted: 03/29/2018] [Indexed: 01/09/2023]
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Merlin A, Shaw R, Chauvin A, Bareille N, Chartier C. Significance of anti-CarLA salivary IgA antibody in first grazing season cattle naturally infected with gastrointestinal nematodes. Vet Parasitol 2017; 243:36-41. [PMID: 28807307 DOI: 10.1016/j.vetpar.2017.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 04/04/2017] [Accepted: 06/05/2017] [Indexed: 11/25/2022]
Abstract
A carbohydrate larval surface antigen (CarLA) present on infective larvae of all trichostrongylid nematodes is a target antigen for host immunoglobulins (Ig). Levels of anti-CarLA salivary IgA antibody (CarLA-IgA) have been shown to be correlated to the level of protective immunity to GIN in sheep and deer but no information is available in cattle. The first objective of this study was to assess the pattern of CarLA-IgA response in 7 groups (G1-G7) of first grazing season cattle (FGSC) naturally infected with gastrointestinal nematodes. The second objective was to assess the phenotypic correlations between CarLA-IgA level, 3 parasitological indicators (faecal egg count-FEC, pepsinogen level, serum anti-O. ostertagi IgG antibody level-OstertagiaIgG), a clinical indicator (diarrhea score) and average daily weight gain (ADWG). Overall, CarLA-IgA response gradually increased over grazing season and showed large variations in speed and magnitude both between and within groups. Based on the mean group CarLA-IgA response pattern, the 7 groups could be allocated to 3 different classes: (i) 'Late High' class characterized by a high response at housing (G1 and G2); (ii) 'Low' class with a low response over time (G3, G4 and G5); and (iii) 'Early' class with an high initial then stable response (G6 and G7). This classification was consistent with the grazing management practices. In the 'Late High' class, the mean CarLA-IgA at housing was 6.05units/mL and negatively correlated with FEC while no correlation was seen with the other indicators nor ADWG. In the 'Low' class, CarLA response at housing was low (1.95units/mL) and mainly positively correlated with OstertagiaIgG. In the 'Early' class, mean CarLA-IgA ranged from 1.32 to 1.86units/mL during the grazing season and positive correlations were seen with parasitological and clinical indicators. These results suggest that, according to the intensity of larval challenge occurring during the first grazing season, CarLA-IgA response in cattle could be either an indicator of the early manifestation of immunity (FEC decreases) or the reflection of exposure to GIN.
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Affiliation(s)
- Aurélie Merlin
- BIOEPAR, INRA, Oniris, La Chantrerie, 44307, Nantes, France.
| | - Richard Shaw
- The Hopkirk Research Institute, AgResearch, Private Bag 11008, Palmerston North 4442, New Zealand
| | - Alain Chauvin
- BIOEPAR, INRA, Oniris, La Chantrerie, 44307, Nantes, France
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Meta-analysis of the parasitic phase traits of Haemonchus contortus infection in sheep. Parasit Vectors 2017; 10:201. [PMID: 28438225 PMCID: PMC5402645 DOI: 10.1186/s13071-017-2131-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 04/05/2017] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The parasitic nematode Haemonchus contortus shows highly variable life history traits. This highlights the need to have an average estimate and a quantification of the variation around it to calibrate epidemiological models. METHODS This paper aimed to quantify the main life history traits of H. contortus and to identify explanatory factors affecting these traits using a powerful method based on a systematic review and meta-analysis of current literature. The life history traits considered are: (i) the establishment rate of ingested larvae; (ii) the adult mortality rate; (iii) the fertility (i.e. the number of eggs laid/female/day); and (iv) fecundity of female worms (i.e. the number of eggs per gram of faeces). RESULTS A total of 37 papers that report single experimental infection with H. contortus in sheep and published from 1960 to 2015, were reviewed and collated in this meta-analysis. This encompassed 115 experiments on 982 animals. Each trait was analysed using a linear model weighted by its inverse variance. The average (± SE) larval establishment rate was 0.24 ± 0.02, which decreased as a function of the infection dose and host age. An average adult mortality rate of 0.021 ± 0.002) was estimated from the literature. This trait varied as a function of animal age, breed and protective response due to prior exposure to the parasite. Average female fertility was 1295.9 ± 280.4 eggs/female/day and decreased in resistant breeds and previously infected hosts. Average faecal egg count at necropsy was 908.5 ± 487.1 eggs per gram of faeces and varied as a function of infection duration and host resistance. The average sex ratio of H. contortus was 0.51 ± 0.006. CONCLUSION This work is the first systematic review to summarise the available information on the parasitic phase of H. contortus in sheep. The results of the meta-analysis provide robust estimates of life history traits for parametrization of epidemiological models, their expected variation according to experimental factors, and provides correlations between these.
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A stochastic model to investigate the effects of control strategies on calves exposed to Ostertagia ostertagi. Parasitology 2016; 143:1755-1772. [PMID: 27573532 PMCID: PMC5074087 DOI: 10.1017/s0031182016001438] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Predicting the effectiveness of parasite control strategies requires accounting for the responses of individual hosts and the epidemiology of parasite supra- and infra-populations. The first objective was to develop a stochastic model that predicted the parasitological interactions within a group of first season grazing calves challenged by Ostertagia ostertagi, by considering phenotypic variation amongst the calves and variation in parasite infra-population. Model behaviour was assessed using variations in parasite supra-population and calf stocking rate. The model showed the initial pasture infection level to have little impact on parasitological output traits, such as worm burdens and FEC, or overall performance of calves, whereas increasing stocking rate had a disproportionately large effect on both parasitological and performance traits. Model predictions were compared with published data taken from experiments on common control strategies, such as reducing stocking rates, the ‘dose and move’ strategy and strategic treatment with anthelmintic at specific times. Model predictions showed in most cases reasonable agreement with observations, supporting model robustness. The stochastic model developed is flexible, with the potential to predict the consequences of other nematode control strategies, such as targeted selective treatments on groups of grazing calves.
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