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Investigating the benefits of targeted selective treatment according to average daily weight gain against gastrointestinal nematodes in Morada Nova lambs. Parasitol Res 2022; 121:2433-2444. [PMID: 35624382 DOI: 10.1007/s00436-022-07549-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/12/2022] [Indexed: 10/18/2022]
Abstract
The objective of this study was to evaluate a method of targeted selective treatment (TST) of Morada Nova lambs, based on the average daily weight gain (DWG). For this, 114 lambs in the rainy and 102 in the dry season were randomized into three treatments: control (CT), routine (RT, treated every 42 days), and targeted selective (TST, treated according to DWG). Packed cell volume (PCV) and eggs per gram of feces (EPG) tests were performed. The anthelmintic resistance of parasites was assessed by the EPG count reduction test (FECRT), RESISTA-Test©, and molecular test. For CT, RT, and TST groups, the following results were obtained: mean EPG values were 4665.1, 3063.5, and 3462.1 in the rainy season and 4475.1, 1341.7, and 2863.4 in the dry season, respectively; mean PCV values were 32.1, 33.4, and 32.3% in the rainy season and 33.9, 36.0, and 35.1% in the dry season; mean DWG readings were 0.087, 0.101, and 0.094 kg in the rainy season and 0.102, 0.113, and 0.112 kg in the dry season; efficacies of levamisole in FECRT were 66.4, 24.1, and 76.4% in the rainy and 90.7, 12.4, and 64.8% in the dry season, respectively; in the RESISTA-Test©, the LC50 values were 0.482, 1.926, and 0.117 µg.mL-1 in the rainy and 0.437, 0.851, and 0.045 µg.mL-1 in the dry season, respectively; the frequencies of the homozygous-resistant genotype were 57.1, 71.4, and 40.0% in the rainy and 47.8, 55.9, and 41.9% in the dry season. In conclusion, TST reduced the development of resistance through refugia maintenance, without productive losses, contributing to the sustainability of sheep breeding.
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2
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Charlier J, Bartley DJ, Sotiraki S, Martinez-Valladares M, Claerebout E, von Samson-Himmelstjerna G, Thamsborg SM, Hoste H, Morgan ER, Rinaldi L. Anthelmintic resistance in ruminants: challenges and solutions. ADVANCES IN PARASITOLOGY 2022; 115:171-227. [PMID: 35249662 DOI: 10.1016/bs.apar.2021.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Anthelmintic resistance (AR) is a growing concern for effective parasite control in farmed ruminants globally. Combatting AR will require intensified and integrated research efforts in the development of innovative diagnostic tests to detect helminth infections and AR, sustainable anthelmintic treatment strategies and the development of complementary control approaches such as vaccination and plant-based control. It will also require a better understanding of socio-economic drivers of anthelmintic treatment decisions, in order to support a behavioural shift and develop targeted communication strategies that promote the uptake of evidence-based sustainable solutions. Here, we review the state-of-the-art in these different fields of research activity related to AR in helminths of livestock ruminants in Europe and beyond. We conclude that in the advent of new challenges and solutions emerging from continuing spread of AR and intensified research efforts, respectively, there is a strong need for transnational multi-actor initiatives. These should involve all key stakeholders to develop indicators of infection and sustainable control, set targets and promote good practices to achieve them.
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Affiliation(s)
| | - D J Bartley
- Disease Control, Moredun Research Institute, Penicuik, United Kingdom
| | - S Sotiraki
- Veterinary Research Institute, Hellenic Agricultural Organisation ELGO-DIMITRA, Thessaloniki, Greece
| | - M Martinez-Valladares
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, León, Spain
| | - E Claerebout
- Ghent University, Faculty of Veterinary Medicine, Laboratory of Parasitology, Merelbeke, Belgium
| | - G von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
| | - S M Thamsborg
- Veterinary Parasitology, University of Copenhagen, Frederiksberg C, Denmark
| | - H Hoste
- INRAE, UMR 1225 IHAP INRAE/ENVT, Toulouse University, Toulouse, France
| | - E R Morgan
- Institute for Global Food Security, Queen's University Belfast, Belfast, United Kingdom
| | - L Rinaldi
- University of Naples Federico II, Unit of Parasitology and Parasitic Diseases, Department of Veterinary Medicine and Animal Production, CREMOPAR, Napoli, Italy.
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3
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Melo LRBD, Sousa LCD, de Menezes Oliveira CS, Alvares FBV, Ferreira LC, Bezerra RA, Athayde ACR, Feitosa TF, Vilela VLR. Resistance of bovine gastrointestinal nematodes to four classes of anthelmintics in the semiarid region of Paraíba state, Brazil. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINARIA 2021; 30:e010921. [PMID: 34550213 DOI: 10.1590/s1984-29612021077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 08/19/2021] [Indexed: 11/22/2022]
Abstract
The effectiveness of four anthelmintic classes on cattle gastrointestinal nematodes in the semi-arid region of Paraiba State, Brazil, was evaluated. Twenty farms were used, testing 40 animals in each one, totaling 800 animals. Cattle were divided into four groups composed with ten animals: I, treated with albendazole sulfoxide 15%; II, treated with ivermectin 1%; III, treated with closantel 25%; IV, treated with levamisole hydrochloride 7.5%. All treatments were administered subcutaneously. For the Fecal Egg Count Reduction Test (FECRT), individual fecal samples were collected on days 0 and 14, and sent for analysis of egg count per gram of feces (EPG) and larval cultures. It was observed that multiresistance was present in 95% (19/20) of the farms. Resistance to ivermectin and albendazole was observed in 95% (19/20), to closantel in 75% (15/20) and to levamisole in 20% (4/20). The most used management system was semi-intensive (75%; 15/20) and the ivermectin was the most reported drug for controlling helminths (65%; 13/20). Haemonchus spp. was the most prevalent helminth genus. It was concluded that the anthelmintic resistance of bovine gastrointestinal nematodes is high in the semi-arid of Paraíba State, Brazil, with multiresistance observed mainly to ivermectin, albendazole and closantel.
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Affiliation(s)
- Lídio Ricardo Bezerra de Melo
- Programa de Pós-graduação em Ciência e Saúde Animal, Universidade Federal de Campina Grande - UFCG, Patos, PB, Brasil
| | - Luana Carneiro de Sousa
- Departamento de Medicina Veterinária, Instituto Federal de Educação, Ciência e Tecnologia da Paraíba - IFPB, Sousa, PB, Brasil
| | | | - Felipe Boniedj Ventura Alvares
- Departamento de Medicina Veterinária, Instituto Federal de Educação, Ciência e Tecnologia da Paraíba - IFPB, Sousa, PB, Brasil
| | - Larissa Claudino Ferreira
- Programa de Pós-graduação em Ciência e Saúde Animal, Universidade Federal de Campina Grande - UFCG, Patos, PB, Brasil
| | - Roberto Alves Bezerra
- Programa de Pós-graduação em Ciência e Saúde Animal, Universidade Federal de Campina Grande - UFCG, Patos, PB, Brasil
| | - Ana Célia Rodrigues Athayde
- Programa de Pós-graduação em Ciência e Saúde Animal, Universidade Federal de Campina Grande - UFCG, Patos, PB, Brasil
| | - Thais Ferreira Feitosa
- Departamento de Medicina Veterinária, Instituto Federal de Educação, Ciência e Tecnologia da Paraíba - IFPB, Sousa, PB, Brasil
| | - Vinícius Longo Ribeiro Vilela
- Programa de Pós-graduação em Ciência e Saúde Animal, Universidade Federal de Campina Grande - UFCG, Patos, PB, Brasil.,Departamento de Medicina Veterinária, Instituto Federal de Educação, Ciência e Tecnologia da Paraíba - IFPB, Sousa, PB, Brasil
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4
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Greer AW, Van Wyk JA, Hamie JC, Byaruhanga C, Kenyon F. Refugia-Based Strategies for Parasite Control in Livestock. Vet Clin North Am Food Anim Pract 2020; 36:31-43. [PMID: 32029187 DOI: 10.1016/j.cvfa.2019.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Refugia-based strategies are intended to help slow the development of anthelmintic resistance by providing a population of parasites that are not exposed to the treatment. Evidence from field studies is lacking. There is no single way to incorporate refugia into a parasite control program. There are many options available varying greatly in complexity and practicality, and none are suitable for all situations. Incorporating refugia into production systems typically requires a change in farmer mindset and greater input of time, labor, and/or technology, but is necessary to help preserve anthelmintic efficacy and promote sustainable animal production systems.
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Affiliation(s)
- Andrew W Greer
- Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Christchurch, Canterbury 7647, New Zealand.
| | - Jan A Van Wyk
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, P/Bag X04, Onderstepoort 0110, South Africa
| | - Joseph C Hamie
- Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Christchurch, Canterbury 7647, New Zealand; Department of Agricultural Research Services, Lunyangwa Agricultural Research Station, PO Box 59, Choma Road, Mzuzu, Malawi
| | - Charles Byaruhanga
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, P/Bag X04, Onderstepoort 0110, South Africa
| | - Fiona Kenyon
- Disease Control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, Scotland
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Abstract
Veterinarians and farmers must contend with the development of drug resistance and climate variability, which threaten the sustainability of current parasite control practices. Field trials evaluating competing strategies for controlling parasites while simultaneously slowing the development of resistance are time consuming and expensive. In contrast, modelling studies can rapidly explore a wide range of scenarios and have generated an array of decision support tools for veterinarians and farmers such as real-time weather-dependent infection risk alerts. Models have also been valuable for predicting the development of anthelmintic resistance, evaluating the sustainability of current parasite control practices and promoting the responsible use of novel anthelmintics.
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Affiliation(s)
- Hannah Rose Vineer
- Veterinary Parasitology, Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Institute of Veterinary Science, Chester High Road, Neston CH64 7TE, UK.
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Takeuchi-Storm N, Moakes S, Thüer S, Grovermann C, Verwer C, Verkaik J, Knubben-Schweizer G, Höglund J, Petkevičius S, Thamsborg S, Werne S. Parasite control in organic cattle farming: Management and farmers' perspectives from six European countries. VETERINARY PARASITOLOGY- REGIONAL STUDIES AND REPORTS 2019; 18:100329. [PMID: 31796188 DOI: 10.1016/j.vprsr.2019.100329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/22/2019] [Accepted: 08/12/2019] [Indexed: 10/26/2022]
Abstract
Organic ruminant production is expanding in the EU, but parasite management remains a constant challenge. Mandatory outdoor access for all age groups can increase exposure to pasture borne parasites, whilst restrictions in the prophylactic use of anthelmintics can limit parasite control. The scientific community has been working to deliver effective parasite control strategies and alternative approaches in order to slow down the development of anthelmintic resistance (AR). However, the current parasite control practices and overall awareness with regards to AR and alternative approaches on farms are largely unknown and may be causing a knowledge gap between the scientific and farming communities. Therefore, a structured survey was conducted in six European countries (Switzerland, Germany, Denmark, Netherlands, Lithuania, Sweden) to provide basic data on practices, management and farmers' perspectives for grazing and parasite control (gastrointestinal worms and liver flukes) on organic cattle farms. Overall, 375 surveys were collected (282 dairy and 93 beef farms) in 2015-2016, and analysed descriptively. Additionally, surveys from the 228 dairy farms were assessed using a double-hurdle adoption model to identify the factors involved in the decision to drench against gastrointestinal parasites. Generally, there are prominent differences between countries, with monitoring methods differing especially, which has important implications in terms of knowledge transfer. For example, media warning was the most common method in DE, while antibody testing in bulk tank milk was the common method in NL. In other countries, clinical signs (diarrhoea, hair coat quality, and reduced weight or yield) and liver condemnation data were used frequently. In general, organic farmers from the six participating countries indicated that they would accept alternative approaches despite greater cost and labour. The likelihood of drenching were higher on farms with smaller farm areas, higher number of young stock and total livestock units and farms where faecal egg counts were used to monitor the parasites. In conclusion, it was evident that grazing and parasite management varied between the countries even though they operate under the same basic principles. Parasite management strategies must therefore be country specific and disseminated with appropriate methods.
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Affiliation(s)
- Nao Takeuchi-Storm
- Research Group for Veterinary Parasitology, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlægevej 100, DK-1871, Frederiksberg C, Denmark.
| | - Simon Moakes
- Research Institute of Organic Agriculture FiBL, Ackerstrasse 113, 5070 Frick, Switzerland.
| | - Susann Thüer
- Research Institute of Organic Agriculture FiBL, Ackerstrasse 113, 5070 Frick, Switzerland.
| | - Christian Grovermann
- Research Institute of Organic Agriculture FiBL, Ackerstrasse 113, 5070 Frick, Switzerland.
| | - Cynthia Verwer
- Louis Bolk Institute, Kosterijland 3-5, 3981 AJ Bunnik, The Netherlands.
| | - Jan Verkaik
- Wageningen Livestock Research, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
| | - Gabriela Knubben-Schweizer
- Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Sonnenstrasse 16, 85764 Oberschleissheim, Germany.
| | - Johan Höglund
- Division of Parasitology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, 75007 Uppsala, Sweden.
| | - Saulius Petkevičius
- Parasitology Laboratory, Department of Veterinary Pathobiology, Veterinary Academy, Lithuanian University of Health Sciences, Tilzes str. 18, LT-47181 Kaunas, Lithuania.
| | - Stig Thamsborg
- Research Group for Veterinary Parasitology, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlægevej 100, DK-1871, Frederiksberg C, Denmark.
| | - Steffen Werne
- Research Institute of Organic Agriculture FiBL, Ackerstrasse 113, 5070 Frick, Switzerland.
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7
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Niewiadomska AM, Jayabalasingham B, Seidman JC, Willem L, Grenfell B, Spiro D, Viboud C. Population-level mathematical modeling of antimicrobial resistance: a systematic review. BMC Med 2019; 17:81. [PMID: 31014341 PMCID: PMC6480522 DOI: 10.1186/s12916-019-1314-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/25/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mathematical transmission models are increasingly used to guide public health interventions for infectious diseases, particularly in the context of emerging pathogens; however, the contribution of modeling to the growing issue of antimicrobial resistance (AMR) remains unclear. Here, we systematically evaluate publications on population-level transmission models of AMR over a recent period (2006-2016) to gauge the state of research and identify gaps warranting further work. METHODS We performed a systematic literature search of relevant databases to identify transmission studies of AMR in viral, bacterial, and parasitic disease systems. We analyzed the temporal, geographic, and subject matter trends, described the predominant medical and behavioral interventions studied, and identified central findings relating to key pathogens. RESULTS We identified 273 modeling studies; the majority of which (> 70%) focused on 5 infectious diseases (human immunodeficiency virus (HIV), influenza virus, Plasmodium falciparum (malaria), Mycobacterium tuberculosis (TB), and methicillin-resistant Staphylococcus aureus (MRSA)). AMR studies of influenza and nosocomial pathogens were mainly set in industrialized nations, while HIV, TB, and malaria studies were heavily skewed towards developing countries. The majority of articles focused on AMR exclusively in humans (89%), either in community (58%) or healthcare (27%) settings. Model systems were largely compartmental (76%) and deterministic (66%). Only 43% of models were calibrated against epidemiological data, and few were validated against out-of-sample datasets (14%). The interventions considered were primarily the impact of different drug regimens, hygiene and infection control measures, screening, and diagnostics, while few studies addressed de novo resistance, vaccination strategies, economic, or behavioral changes to reduce antibiotic use in humans and animals. CONCLUSIONS The AMR modeling literature concentrates on disease systems where resistance has been long-established, while few studies pro-actively address recent rise in resistance in new pathogens or explore upstream strategies to reduce overall antibiotic consumption. Notable gaps include research on emerging resistance in Enterobacteriaceae and Neisseria gonorrhoeae; AMR transmission at the animal-human interface, particularly in agricultural and veterinary settings; transmission between hospitals and the community; the role of environmental factors in AMR transmission; and the potential of vaccines to combat AMR.
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Affiliation(s)
- Anna Maria Niewiadomska
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA
| | - Bamini Jayabalasingham
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA.,Present Address: Elsevier Inc., 230 Park Ave, Suite B00, New York, NY, 10169, USA
| | - Jessica C Seidman
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA
| | | | - Bryan Grenfell
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA.,Princeton University, Princeton, NJ, USA
| | - David Spiro
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA
| | - Cecile Viboud
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, USA.
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Risi G, Aguilera E, Ladós E, Suárez G, Carrera I, Álvarez G, Salinas G. Caenorhabditis elegans Infrared-Based Motility Assay Identified New Hits for Nematicide Drug Development. Vet Sci 2019; 6:vetsci6010029. [PMID: 30884899 PMCID: PMC6466232 DOI: 10.3390/vetsci6010029] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 12/17/2022] Open
Abstract
Nematode parasites have a profound impact on humankind, infecting nearly one-quarter of the world’s population, as well as livestock. There is a pressing need for discovering nematicides due to the spread of resistance to currently used drugs. The free-living nematode Caenorhabditis elegans is a formidable experimentally tractable model organism that offers key advantages in accelerating nematicide discovery. We report the screening of drug-like libraries using an overnight high-throughput C. elegans assay, based on an automated infrared motility reader. As a proof of concept, we screened the “Pathogen Box” library, and identical results to a previous screen using Haemonchus contortus were obtained. We then screened an in-house library containing a diversity of compound families. Most active compounds had a conjugation of an unsaturation with an electronegative atom (N, O, or S) and an aromatic ring. Importantly, we identified symmetric arylidene ketones and aryl hydrazine derivatives as novel nematicides. Furthermore, one of these compounds, (1E,2E)-1,2-bis(thiophen-3-ylmethylene)hydrazine, was active as a nematicide at 25 µm, but innocuous to the vertebrate model zebrafish at 50 µm. Our results identified novel nematicidal scaffolds and illustrate the value of C. elegans in accelerating nematicide discovery using a nonlabor-intensive automated assay that provides a simple overnight readout.
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Affiliation(s)
- Gastón Risi
- Worm Biology Laboratory, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay.
| | - Elena Aguilera
- Grupo de Química Medicinal, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay.
| | - Enrique Ladós
- Worm Biology Laboratory, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay.
| | - Gonzalo Suárez
- Área Farmacología, Departamento de Fisiología, Facultad de Veterinaria, Universidad de la República, Montevideo 11600, Uruguay.
| | - Inés Carrera
- Worm Biology Laboratory, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay.
- Departamento de Ciencias Farmacéuticas, Área Farmacología, Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay.
| | - Guzmán Álvarez
- Laboratorio de Moléculas Bioactivas-CENUR Litoral Norte, Universidad de la República, Paysandú 60000, Uruguay.
| | - Gustavo Salinas
- Worm Biology Laboratory, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay.
- Departamento de Biociencias, Facultad de Química, Universidad de la República, Montevideo 11400, Uruguay.
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9
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Abstract
Helminth infections have large negative impacts on production efficiency in ruminant farming systems worldwide, and their effective management is essential if livestock production is to increase to meet future human needs for dietary protein. The control of helminths relies heavily on routine use of chemotherapeutics, but this approach is unsustainable as resistance to anthelmintic drugs is widespread and increasing. At the same time, infection patterns are being altered by changes in climate, land-use and farming practices. Future farms will need to adopt more efficient, robust and sustainable control methods, integrating ongoing scientific advances. Here, we present a vision of helminth control in farmed ruminants by 2030, bringing to bear progress in: (1) diagnostic tools, (2) innovative control approaches based on vaccines and selective breeding, (3) anthelmintics, by sustainable use of existing products and potentially new compounds, and (4) rational integration of future control practices. In this review, we identify the technical advances that we believe will place new tools in the hands of animal health decision makers in 2030, to enhance their options for control and allow them to achieve a more integrated and sustainable approach to helminth control in support of animal welfare and production.
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10
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A´sbjo¨rnsdo´ttir KH, Means AR, Werkman M, Walson JL. Prospects for elimination of soil-transmitted helminths. Curr Opin Infect Dis 2017; 30:482-488. [PMID: 28700363 PMCID: PMC7680933 DOI: 10.1097/qco.0000000000000395] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW Soil-transmitted helminths (STH) are endemic in 120 countries and are associated with substantial morbidity and loss of economic productivity. Although current WHO guidelines focus on morbidity control through mass drug administration (MDA), there is global interest in whether a strategy targeting disease elimination might be feasible in some settings. This review summarizes the prospects for switching from control to an elimination strategy. RECENT FINDINGS STH control efforts have reduced the intensity of infections in targeted populations with associated reductions in morbidity. However, adults are not frequently targeted and remain important reservoirs for reinfection of treated children. Recent modeling suggests that transmission interruption may be possible through expanded community-wide delivery of MDA, the feasibility of which has been demonstrated by other programs. However, these models suggest that high levels of coverage and compliance must be achieved. Potential challenges include the risk of prematurely dismantling STH programs and the potential increased risk of antihelminthic resistance. SUMMARY Elimination of STH may offer an opportunity to eliminate substantial STH-related morbidity while reducing resource needs of neglected tropical disease programs. Evidence from large community trials is needed to determine the feasibility of interrupting the transmission of STH in some geographic settings.
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Affiliation(s)
- Kristjana H. A´sbjo¨rnsdo´ttir
- DeWorm3, The Natural History Museum, London, UK
- Department of Global Health, University of Washington, Seattle, Washington, USA and
| | - Arianna R. Means
- DeWorm3, The Natural History Museum, London, UK
- Department of Global Health, University of Washington, Seattle, Washington, USA and
| | - Marleen Werkman
- DeWorm3, The Natural History Museum, London, UK
- Department of Infectious Disease Epidemiology, London Centre for Neglected Tropical Disease Research (LCNTDR), St. Mary’s Campus, Imperial College London, London, UK
| | - Judd L. Walson
- DeWorm3, The Natural History Museum, London, UK
- Department of Global Health, University of Washington, Seattle, Washington, USA and
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11
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Jackson A, Ellis KA, McGoldrick J, Jonsson NN, Stear MJ, Forbes AB. Targeted anthelmintic treatment of parasitic gastroenteritis in first grazing season dairy calves using daily live weight gain as an indicator. Vet Parasitol 2017; 244:85-90. [PMID: 28917324 DOI: 10.1016/j.vetpar.2017.07.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 07/16/2017] [Accepted: 07/22/2017] [Indexed: 12/26/2022]
Abstract
Control of parasitic gastroenteritis in cattle is typically based on group treatments with anthelmintics, complemented by grazing management, where feasible. However, the almost inevitable evolution of resistance in parasitic nematodes to anthelmintics over time necessitates a reappraisal of their use in order to reduce selection pressure. One such approach is targeted selective treatment (TST), in which only individual animals that will most benefit are treated, rather than whole groups of at-risk cattle. This study was designed to assess the feasibility of implementing TST on three commercial farms, two of which were organic. A total of 104 first-grazing season (FGS), weaned dairy calves were enrolled in the study; each was weighed at monthly intervals from the start of the grazing season using scales or weigh-bands. At the same time dung and blood samples were collected in order to measure faecal egg counts (FEC) and plasma pepsinogen, respectively. A pre-determined threshhold weight gain of 0.75kg/day was used to determine those animals that would be treated; the anthelmintic used was eprinomectin. No individual animal received more than one treatment during the grazing season and all treatments were given in July or August; five animals were not treated at all because their growth rates consistently exceeded the threshold. Mean daily live weight gain over the entire grazing season ranged between 0.69 and 0.82kg/day on the three farms. Neither FEC nor pepsinogen values were significantly associated with live weight gain. Implementation of TST at farm level requires regular (monthly) handling of the animals and the use of weigh scales or tape, but can be integrated into farm management practices. This study has shown that acceptable growth rates can be achieved in FGS cattle with modest levels of treatment and correspondingly less exposure of their nematode populations to anthelmintics, which should mitigate selection pressure for resistance by increasing the size of the refugia in both hosts and pasture.
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Affiliation(s)
- A Jackson
- Scottish Centre for Production Animal Health and Food Safety, School of Veterinary Medicine, College of Veterinary and Life Sciences; University of Glasgow, Bearsden, Glasgow, G61 1Q, United Kingdom
| | - K A Ellis
- Scottish Centre for Production Animal Health and Food Safety, School of Veterinary Medicine, College of Veterinary and Life Sciences; University of Glasgow, Bearsden, Glasgow, G61 1Q, United Kingdom
| | - J McGoldrick
- Scottish Centre for Production Animal Health and Food Safety, School of Veterinary Medicine, College of Veterinary and Life Sciences; University of Glasgow, Bearsden, Glasgow, G61 1Q, United Kingdom
| | - N N Jonsson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Veterinary and Life Sciences; University of Glasgow, Bearsden, Glasgow, G61 1Q, United Kingdom
| | - M J Stear
- La Trobe University, Animal, Plant and Soil Sciences, Melbourne, Australia
| | - A B Forbes
- Scottish Centre for Production Animal Health and Food Safety, School of Veterinary Medicine, College of Veterinary and Life Sciences; University of Glasgow, Bearsden, Glasgow, G61 1Q, United Kingdom.
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Berk Z, Laurenson YCSM, Forbes AB, Kyriazakis I. Modelling the impacts of pasture contamination and stocking rate for the development of targeted selective treatment strategies for Ostertagia ostertagi infection in calves. Vet Parasitol 2017; 238:82-86. [PMID: 28408216 PMCID: PMC5441451 DOI: 10.1016/j.vetpar.2017.03.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 02/01/2023]
Abstract
Stocking rate effect on design of targeted selective treatments (TST) was evaluated. Initial pasture contamination effect on the design of TST was evaluated. Different phenotypic traits and methods of selection for treatment were addressed. Benefit was assessed as weight gain/frequency of resistant alleles in helminths. Treatment according to threshold triggers of average daily gain was most beneficial.
A simulation study was carried out to assess whether variation in pasture contamination or stocking rate impact upon the optimal design of targeted selective treatment (TST) strategies. Two methods of TST implementation were considered: 1) treatment of a fixed percentage of a herd according to a given phenotypic trait, or 2) treatment of individuals that exceeded a threshold value for a given phenotypic trait. Four phenotypic traits, on which to base treatment were considered: 1) average daily bodyweight gain, 2) faecal egg count, 3) plasma pepsinogen, or 4) random selection. Each implementation method (fixed percentage or threshold treatment) and determinant criteria (phenotypic trait) was assessed in terms of benefit per R (BPR), the ratio of average benefit in weight gain to change in frequency of resistance alleles R (relative to an untreated population). The impact of pasture contamination on optimal TST strategy design was investigated by setting the initial pasture contamination to 100, 200 or 500 O. ostertagi L3/kg DM herbage; stocking rate was investigated at a low (3calves/ha), conventional (5 calves/ha) or high (7 calves/ha) stocking rates. When treating a fixed percentage of the herd, treatments according to plasma pepsinogen or random selection were identified as the most beneficial (i.e. resulted in the greatest BPR) for all levels of initial pasture contamination and all stocking rates. Conversely when treatments were administered according to threshold values ADG was most beneficial, and was identified as the best TST strategy (i.e. resulted in the greatest overall BPR) for all levels of initial pasture contamination and all stocking rates.
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Affiliation(s)
- Zoe Berk
- School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Yan C S M Laurenson
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Andrew B Forbes
- Scottish Centre for Production Animal Health and Food Safety, School of Veterinary Medicine, University of Glasgow, G61 1QH, Scotland, UK
| | - Ilias Kyriazakis
- School of Agriculture Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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