1
|
Geddes E, Morgan-Davies C, McLaren A, Skuce PJ, Duncan JM, Sargison N, Kenyon F. Investigating the perceived versus actual gastrointestinal nematode challenge on extensive sheep farms. Vet Parasitol 2024; 327:110148. [PMID: 38364348 DOI: 10.1016/j.vetpar.2024.110148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/09/2024] [Accepted: 02/11/2024] [Indexed: 02/18/2024]
Abstract
Extensive farming systems form an integral part of sheep production systems across Europe. However, with innate production handicaps, declining sheep numbers and narrow economic margins, production is becoming increasingly challenging threatening the future sustainability of the industry. Gastrointestinal nematodes (GINs) are a significant cause of production losses to the global sheep industry, with well-established resistance to the major anthelmintic groups. Traditionally, extensive farming systems are not thought to have a significant parasite challenge compared with intensive farms, but there is a need to identify the scale and importance of GINs on extensive farms to inform the need for sustainable control strategies. In this study, a questionnaire of extensive farmers (n=34) was conducted and parasitological data were collected from nine study farms to investigate the perceived versus actual GIN and anthelmintic resistance challenge faced by extensive farms. The results showed a production-limiting challenge on most farms, with a higher GIN challenge observed on improved pastures. Furthermore, over half of the extensive farmers perceived anthelmintic resistance to be a greater problem for intensive farmers, with only 20% of respondents reporting known anthelmintic resistance. However, all study farms had evidence of resistance to at least one group of anthelmintics. Consequently, this study has demonstrated that despite the traditional perception of parasitism on extensive farms, there is a need to increasingly consider its impact and take a proactive approach to sustainable control, with solutions tailored to their unique management.
Collapse
Affiliation(s)
- Eilidh Geddes
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Edinburgh EH25 0PZ, UK.
| | - Claire Morgan-Davies
- Scotland's Rural College (SRUC), Hill & Mountain Research Centre, Kirkton, Crianlarich FK20 8RU, UK
| | - Ann McLaren
- Scotland's Rural College (SRUC), Hill & Mountain Research Centre, Kirkton, Crianlarich FK20 8RU, UK
| | - Philip J Skuce
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Edinburgh EH25 0PZ, UK
| | - Jade M Duncan
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Edinburgh EH25 0PZ, UK
| | - Neil Sargison
- The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Midlothian, Edinburgh EH25 9RG, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Edinburgh EH25 0PZ, UK
| |
Collapse
|
2
|
Evans MJ, Corripio-Miyar Y, Hayward A, Kenyon F, McNeilly TN, Nussey DH. Antagonism between co-infecting gastrointestinal nematodes: A meta-analysis of experimental infections in Sheep. Vet Parasitol 2023; 323:110053. [PMID: 37879240 DOI: 10.1016/j.vetpar.2023.110053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/08/2023] [Accepted: 10/11/2023] [Indexed: 10/27/2023]
Abstract
Gastrointestinal nematodes (GIN) have enormous global impacts in humans, wildlife and grazing livestock. Within grazing livestock, sheep are of particular global importance and the economics and sustainability of sheep production are greatly constrained by GIN infections. Natural infections are composed of co-infections with multiple species, and while some past work suggests species can interact negatively with one another within the same host, there is wide variation in reported patterns. Here, we undertook a systematic literature search and meta-analysis of experimental GIN co-infections of sheep to determine whether these experimental studies support the hypothesis of antagonistic interactions between different co-infecting GIN, and test whether aspects of parasite biology or experimental design influence the observed effects. A systematic search of the literature yielded 4848 studies, within which, we identified 19 experimental sheep studies comparing post-mortem worm counts across two co-infecting GIN species. Meta-analysis of 67 effects obtained from these studies provides strong evidence for interactions between GIN species. There was wide variation in the strength and direction of these interactions, but the global effect was significantly antagonistic. On average, there was a decrease in the number of worms of one species when a co-infecting species was also present, relative to a mono-infection with that species alone. This effect was dependent on the infectious dose and was rapidly lost after anthelmintic treatment, suggesting that live worms are required for the effect to occur. Individual parasite species varied in the extent to which they both exerted, and were subject to, these interspecies interactions, and these differences are more complex than simply co-localisation within the gastrointestinal tract. Antagonistic interactions between co-infecting GIN may feedback into their epidemiology as well as potentially affecting the clinical impacts of infection. Furthermore, the consequences of these interactions may be heightened when clinical interventions affect only one species within the co-infecting network. Whilst it was not possible to identify the causes of variation between GIN species in the impact of co-infection, these findings point to new avenues for epidemiological, clinical and mechanistic research on GIN co-infections.
Collapse
Affiliation(s)
- M J Evans
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, UK; Department for Disease Control, Moredun Research Institute, Penicuik, UK; Institute for Ecology and Evolution, University of Edinburgh, Edinburgh, UK.
| | - Y Corripio-Miyar
- Department for Disease Control, Moredun Research Institute, Penicuik, UK
| | - A Hayward
- Department for Disease Control, Moredun Research Institute, Penicuik, UK
| | - F Kenyon
- Department for Disease Control, Moredun Research Institute, Penicuik, UK
| | - T N McNeilly
- Department for Disease Control, Moredun Research Institute, Penicuik, UK
| | - D H Nussey
- Institute for Ecology and Evolution, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
3
|
Acerini CI, Morris S, Morris A, Kenyon F, McBean D, Pemberton JM, Albery GF. Helminth parasites are associated with reduced survival probability in young red deer. Parasitology 2022; 149:1702-1708. [PMID: 36052566 PMCID: PMC11010593 DOI: 10.1017/s0031182022001111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/06/2022] [Accepted: 07/28/2022] [Indexed: 12/14/2022]
Abstract
Helminths are common parasites of wild ungulates that can have substantial costs for growth, mortality and reproduction. Whilst these costs are relatively well documented for mature animals, knowledge of helminths' impacts on juveniles is more limited. Identifying these effects is important because young individuals are often heavily infected, and juvenile mortality is a key process regulating wild populations. Here, we investigated associations between helminth infection and overwinter survival in juvenile wild red deer (Cervus elaphus) on the Isle of Rum, Scotland. We collected fecal samples non-invasively from known individuals and used them to count propagules of 3 helminth taxa (strongyle nematodes, Fasciola hepatica and Elaphostrongylus cervi). Using generalized linear models, we investigated associations between parasite counts and overwinter survival for calves and yearlings. Strongyles were associated with reduced survival in both age classes, and F. hepatica was associated with reduced survival in yearlings, whilst E. cervi infection showed no association with survival in either age class. This study provides observational evidence for fitness costs of helminth infection in juveniles of a wild mammal, and suggests that these parasites could play a role in regulating population dynamics.
Collapse
Affiliation(s)
- Claudia I. Acerini
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Sean Morris
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Alison Morris
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian EH26 0PZ, UK
| | - David McBean
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian EH26 0PZ, UK
| | - Josephine M. Pemberton
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Gregory F. Albery
- Wissenschaftskolleg zu Berlin, Berlin 14193, Germany
- Department of Biology, Georgetown University, Washington, DC 20007, USA
| |
Collapse
|
4
|
Sweeny AR, Corripio-Miyar Y, Bal X, Hayward AD, Pilkington JG, McNeilly TN, Nussey DH, Kenyon F. Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population - CORRIGENDUM. Parasitology 2022; 149:1-2. [PMID: 35357292 PMCID: PMC10090568 DOI: 10.1017/s0031182022000324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
5
|
Corripio-Miyar Y, Hayward A, Lemon H, Sweeny AR, Bal X, Kenyon F, Pilkington JG, Pemberton JM, Nussey DH, McNeilly TN. Functionally distinct T-helper cell phenotypes predict resistance to different types of parasites in a wild mammal. Sci Rep 2022; 12:3197. [PMID: 35210503 PMCID: PMC8873199 DOI: 10.1038/s41598-022-07149-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/04/2022] [Indexed: 12/31/2022] Open
Abstract
The adaptive immune system is critical to an effective response to infection in vertebrates, with T-helper (Th) cells pivotal in orchestrating these responses. In natural populations where co-infections are the norm, different Th responses are likely to play an important role in maintaining host health and fitness, a relationship which remains poorly understood in wild animals. In this study, we characterised variation in functionally distinct Th responses in a wild population of Soay sheep by enumerating cells expressing Th-subset specific transcription factors and quantifying Th-associated cytokines. We tested the prediction that raised Th1 and Th2 responses should predict reduced apicomplexan and helminth parasite burdens, respectively. All measures of Th-associated cytokine production increased with age, while Th17- and regulatory Th-associated cytokine production increased more rapidly with age in males than females. Independent of age, sex, and each other, IL-4 and Gata3 negatively predicted gastro-intestinal nematode faecal egg count, while IFN-γ negatively predicted coccidian faecal oocyst count. Our results provide important support from outside the laboratory that Th1 and Th2 responses predict resistance to different kinds of parasites, and illustrate how harnessing specific reagents and tools from laboratory immunology will illuminate our understanding of host-parasite interactions in the wild.
Collapse
Affiliation(s)
- Yolanda Corripio-Miyar
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, EH26 0PZ, UK.
| | - Adam Hayward
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, EH26 0PZ, UK
| | - Hannah Lemon
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Amy R Sweeny
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Xavier Bal
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, EH26 0PZ, UK
| | - Jill G Pilkington
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Josephine M Pemberton
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Daniel H Nussey
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, EH26 0PZ, UK
| |
Collapse
|
6
|
Sweeny AR, Corripio-Miyar Y, Bal X, Hayward AD, Pilkington JG, McNeilly TN, Nussey DH, Kenyon F. Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population. Parasitology 2022; 149:1-12. [PMID: 35264257 PMCID: PMC10090596 DOI: 10.1017/s0031182021001980] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/09/2021] [Accepted: 11/01/2021] [Indexed: 11/07/2022]
Abstract
Within-year variation in infection is a ubiquitous feature of natural populations, but is determined by a complex interplay of environmental, parasitological and host factors. At the same time, co-infection is the norm in the wild. Longitudinal dynamics of co-infecting parasites may therefore be further complicated by covariation across multiple parasites. Here, we used fecal parasite egg and oocyst counts collected repeatedly from individually marked wild Soay sheep to investigate seasonal dynamics of six gastrointestinal parasite groups. Prevalence and abundance tended to be higher in spring and summer, and abundance was higher in lambs compared to adults. We found that within-year variation in highly prevalent strongyle nematode counts was dependent on adult reproductive status, where reproductive ewes had distinct dynamics compared to males and barren ewes. For similarly prevalent coccidia we found an overall peak in oocyst counts in spring but no differences among males, barren and pregnant ewes. Using multivariate mixed-effects models, we further show that apparent positive correlation between strongyle and coccidia counts was driven by short-term within-individual changes in both counts rather than long-term among-individual covariation. Overall, these results demonstrate that seasonality varies across demographic and parasite groups and highlight the value of investigating co-infection dynamics over time.
Collapse
Affiliation(s)
- Amy R. Sweeny
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | | | - Xavier Bal
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | | | - Jill G. Pilkington
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | | | - Daniel H. Nussey
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | | |
Collapse
|
7
|
Melville LA, Hayward A, Morgan ER, Shaw DJ, McBean D, Andrews L, Morrison A, Kenyon F. Precision worm control in grazing lambs by targeting group treatment based on performance of sentinels. Animal 2021; 15:100176. [PMID: 33637437 DOI: 10.1016/j.animal.2021.100176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 12/21/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022] Open
Abstract
Given the economic impact of gastrointestinal nematode infection on livestock farming worldwide, and increasing anthelmintic resistance, it is imperative to develop practical, efficient and sustainable control strategies. Targeted selective treatment (TST), whereby anthelmintic treatments are administered to animals individually, based on selection criteria such as weight gain, has been shown to successfully maintain animal productivity whilst reducing the selection pressure for anthelmintic resistance and the economic cost of treatment in experimental and commercial settings. Despite the benefits of the TST approach, the equipment and time required to monitor animals individually make this strategy unsuitable for some farming enterprises. The sentinel group approach aims to maintain the benefits observed using TST whilst reducing these requirements. The study involved two experiments, each following a group of 80 lambs through their first grazing season. Anthelmintic treatment of the whole group was determined by monitoring the weight gain of identified sentinel lambs within it every 2 weeks: when 40% of the sentinel lambs failed to reach their weight gain targets, the whole group was treated. The sentinel lambs consisted of 45% of the group (n = 36) in experiment one and 20% (n = 16) in experiment two. A control group of 20 lambs was co-grazed with the main group during both experiments; in experiment one, the sentinel approach was compared with a TST approach, in which control lambs were treated on an individual basis in response to weight gain. In experiment two, the sentinel approach was compared with conventional prophylaxis, where all lambs in the control group were treated at strategic time points throughout the season (= strategic prophylactic treatment). The sentinel lambs were found to be representative of overall group performance regardless of the proportion of sentinels within the group: they recorded similar growth rates and reached weight gain targets simultaneously at each time point and overall. Live-weight gain was also similar between sentinel and control animals in both experiments. The findings of the current study suggest that monitoring sentinel lambs comprising 20% of a group of grazing lambs is sufficient to determine the need for anthelmintic treatment within the whole group, and that this approach maintains production in line with conventional or TST treatment regimes.
Collapse
Affiliation(s)
- L A Melville
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK.
| | - A Hayward
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK
| | - E R Morgan
- Queens University Belfast, School of Biological Sciences, 19, Chlorine Gardens, Belfast BT9 5DL, UK
| | - D J Shaw
- Royal (Dick) School of Veterinary Studies & Roslin Institute, The University of Edinburgh, Easter Bush Campus, Roslin EH25 9RG, UK
| | - D McBean
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK
| | - L Andrews
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK
| | - A Morrison
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK
| | - F Kenyon
- Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK
| |
Collapse
|
8
|
McBean DW, Greer AW, Kenyon F. The Happy Factor treatment threshold, used to determine Targeted Selective Treatment decisions for lambs, is transferable between farms. Animal 2021; 15:100178. [PMID: 33589351 DOI: 10.1016/j.animal.2021.100178] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 01/06/2021] [Accepted: 01/08/2021] [Indexed: 10/22/2022] Open
Abstract
Weight gain-based treatment decision-making has been shown to successfully reduce the number of anthelmintic treatments without compromising production as part of a Targeted Selective Treatment (TST)-based worm control strategy in sheep. The effects of using an efficiency threshold (Standard Threshold (ST)) developed on one farm were examined to establish whether there was a need to tailor the threshold for individual farm conditions. The Standard Threshold had been used on a number of farms, and data from these trials were used here. The ideal threshold (Estimated Treatment Threshold) for each farm was calculated using the same method as the original threshold, and the effect on the number of treatments given and subsequent productivity was estimated. Estimated treatment thresholds were calculated to be higher on all farms including the original, resulting in increased numbers of treatments due. The effect of the increased number of treatments was calculated to have no effect on productivity however, and it was concluded that the ST was sufficient, at least initially, for successful implementation of TST and that further refinement could be made using locally derived data if required.
Collapse
Affiliation(s)
- D W McBean
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, Scotland, United Kingdom.
| | - A W Greer
- Faculty of Agriculture and Life Sciences, P.O. Box 85084, Lincoln University, Lincoln 7647, New Zealand
| | - F Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, Scotland, United Kingdom
| |
Collapse
|
9
|
Albery GF, Morris A, Morris S, Kenyon F, Nussey DH, Pemberton JM. Fitness Costs of Parasites Explain Multiple Life-History Trade-Offs in a Wild Mammal. Am Nat 2021; 197:324-335. [PMID: 33625970 DOI: 10.1086/712633] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractReproduction in wild animals can divert limited resources away from immune defense, resulting in increased parasite burdens. A long-standing prediction of life-history theory states that these parasites can harm the reproductive individual, reducing its subsequent survival and fecundity, producing reproduction-fitness trade-offs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent survival and fecundity in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation in terms of downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life-history trade-offs, supporting the role of parasites as an important mediating factor in wild mammal populations.
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
Albery GF, Becker DJ, Kenyon F, Nussey DH, Pemberton JM. The Fine-Scale Landscape of Immunity and Parasitism in a Wild Ungulate Population. Integr Comp Biol 2020; 59:1165-1175. [PMID: 30942858 DOI: 10.1093/icb/icz016] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Spatial heterogeneity in susceptibility and exposure to parasites is a common source of confounding variation in disease ecology studies. However, it is not known whether spatial autocorrelation acts on immunity at small scales, within wild animal populations, and whether this predicts spatial patterns in infection. Here we used a well-mixed wild population of individually recognized red deer (Cervus elaphus) inhabiting a heterogeneous landscape to investigate fine-scale spatial patterns of immunity and parasitism. We noninvasively collected 842 fecal samples from 141 females with known ranging behavior over 2 years. We quantified total and helminth-specific mucosal antibodies and counted propagules of three gastrointestinal helminth taxa. These data were analyzed with linear mixed models using the Integrated Nested Laplace Approximation, using a Stochastic Partial Differentiation Equation approach to control for and quantify spatial autocorrelation. We also investigated whether spatial patterns of immunity and parasitism changed seasonally. We discovered substantial spatial heterogeneity in general and helminth-specific antibody levels and parasitism with two helminth taxa, all of which exhibited contrasting seasonal variation in their spatial patterns. Notably, Fasciola hepatica intensity appeared to be strongly influenced by the presence of wet grazing areas, and antibody hotspots did not correlate with distributions of any parasites. Our results suggest that spatial heterogeneity may be an important factor affecting immunity and parasitism in a wide range of study systems. We discuss these findings with regards to the design of sampling regimes and public health interventions, and suggest that disease ecology studies investigate spatial heterogeneity more regularly to enhance their results, even when examining small geographic areas.
Collapse
Affiliation(s)
- Gregory F Albery
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Daniel J Becker
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Fiona Kenyon
- Pentlands Science Park, Moredun Research Institute, Bush Loan, Midlothian EH26 0PZ, UK
| | - Daniel H Nussey
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Josephine M Pemberton
- Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3FL, UK
| |
Collapse
|
12
|
Albery GF, Watt KA, Keith R, Morris S, Morris A, Kenyon F, Nussey DH, Pemberton JM. Reproduction has different costs for immunity and parasitism in a wild mammal. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13475] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Gregory F. Albery
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Kathryn A. Watt
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Rosie Keith
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Sean Morris
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Alison Morris
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Fiona Kenyon
- Moredun Research Institute Pentlands Science Park Midlothian UK
| | - Daniel H. Nussey
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Josephine M. Pemberton
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| |
Collapse
|
13
|
Hodgkinson JE, Kaplan RM, Kenyon F, Morgan ER, Park AW, Paterson S, Babayan SA, Beesley NJ, Britton C, Chaudhry U, Doyle SR, Ezenwa VO, Fenton A, Howell SB, Laing R, Mable BK, Matthews L, McIntyre J, Milne CE, Morrison TA, Prentice JC, Sargison ND, Williams DJL, Wolstenholme AJ, Devaney E. Refugia and anthelmintic resistance: Concepts and challenges. Int J Parasitol Drugs Drug Resist 2019; 10:51-57. [PMID: 31125837 PMCID: PMC6531808 DOI: 10.1016/j.ijpddr.2019.05.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/10/2019] [Accepted: 05/12/2019] [Indexed: 12/17/2022]
Abstract
Anthelmintic resistance is a threat to global food security. In order to alleviate the selection pressure for resistance and maintain drug efficacy, management strategies increasingly aim to preserve a proportion of the parasite population in 'refugia', unexposed to treatment. While persuasive in its logic, and widely advocated as best practice, evidence for the ability of refugia-based approaches to slow the development of drug resistance in parasitic helminths is currently limited. Moreover, the conditions needed for refugia to work, or how transferable those are between parasite-host systems, are not known. This review, born of an international workshop, seeks to deconstruct the concept of refugia and examine its assumptions and applicability in different situations. We conclude that factors potentially important to refugia, such as the fitness cost of drug resistance, the degree of mixing between parasite sub-populations selected through treatment or not, and the impact of parasite life-history, genetics and environment on the population dynamics of resistance, vary widely between systems. The success of attempts to generate refugia to limit anthelmintic drug resistance are therefore likely to be highly dependent on the system in hand. Additional research is needed on the concept of refugia and the underlying principles for its application across systems, as well as empirical studies within systems that prove and optimise its usefulness.
Collapse
Affiliation(s)
- Jane E Hodgkinson
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Ray M Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Edinburgh, EH26 0PZ, UK
| | - Eric R Morgan
- School of Biological Sciences, Queen's University Belfast, Chlorine Gardens, Belfast, BT9 5BL, UK
| | - Andrew W Park
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA; Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, L69 7ZB, UK
| | - Simon A Babayan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Nicola J Beesley
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Collette Britton
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Umer Chaudhry
- Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
| | - Stephen R Doyle
- Wellcome Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA; Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, L69 7ZB, UK
| | - Sue B Howell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Roz Laing
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Barbara K Mable
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Louise Matthews
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Jennifer McIntyre
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Catherine E Milne
- SRUC, Peter Wilson Building, West Mains Road, Edinburgh, EH9 3JG, UK
| | - Thomas A Morrison
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Jamie C Prentice
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Neil D Sargison
- Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
| | - Diana J L Williams
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Eileen Devaney
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK.
| |
Collapse
|
14
|
Morgan ER, Aziz NAA, Blanchard A, Charlier J, Charvet C, Claerebout E, Geldhof P, Greer AW, Hertzberg H, Hodgkinson J, Höglund J, Hoste H, Kaplan RM, Martínez-Valladares M, Mitchell S, Ploeger HW, Rinaldi L, von Samson-Himmelstjerna G, Sotiraki S, Schnyder M, Skuce P, Bartley D, Kenyon F, Thamsborg SM, Vineer HR, de Waal T, Williams AR, van Wyk JA, Vercruysse J. 100 Questions in Livestock Helminthology Research. Trends Parasitol 2018; 35:52-71. [PMID: 30477758 DOI: 10.1016/j.pt.2018.10.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 12/22/2022]
Abstract
An elicitation exercise was conducted to collect and identify pressing questions concerning the study of helminths in livestock, to help guide research priorities. Questions were invited from the research community in an inclusive way. Of 385 questions submitted, 100 were chosen by online vote, with priority given to open questions in important areas that are specific enough to permit investigation within a focused project or programme of research. The final list of questions was divided into ten themes. We present the questions and set them briefly in the context of the current state of knowledge. Although subjective, the results provide a snapshot of current concerns and perceived priorities in the field of livestock helminthology, and we hope that they will stimulate ongoing or new research efforts.
Collapse
Affiliation(s)
- Eric R Morgan
- Queen's University Belfast, School of Biological Sciences, 97, Lisburn Road, Belfast, BT9 7BL, UK.
| | - Nor-Azlina A Aziz
- Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | | | | | - Claude Charvet
- ISP, INRA, Université Tours, UMR1282, 37380, Nouzilly, France
| | - Edwin Claerebout
- Laboratory for Parasitology, Faculty of Veterinary Medicine, Ghent University, B9820 Merelbeke, Belgium
| | - Peter Geldhof
- Laboratory for Parasitology, Faculty of Veterinary Medicine, Ghent University, B9820 Merelbeke, Belgium
| | - Andrew W Greer
- Faculty of Agriculture and Life Sciences, P.O. Box 85084, Lincoln University, Christchurch, 7647, New Zealand
| | - Hubertus Hertzberg
- Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
| | - Jane Hodgkinson
- Institute of Infection and Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool, L3 5RF, UK
| | - Johan Höglund
- Swedish University of Agricultural Sciences, BVF-parasitology, Box 7036, 750 07, Uppsala, Sweden
| | - Hervé Hoste
- UMR 1225 IHAP INRA/ENVT, 23 Chemin des Capelles, 31076 Toulouse, France
| | - Ray M Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - María Martínez-Valladares
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas, Grulleros, 24346 León, Spain
| | - Siân Mitchell
- Animal and Plant Health Agency, Carmarthen Veterinary Investigation Centre, Jobswell Road, Johnstown, Carmarthen, SA31 3EZ, UK
| | - Harm W Ploeger
- Utrecht University, Department of Infectious Diseases and Immunology, Yalelaan 1, 3584 CL, Utrecht, The Netherlands
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Napoli Federico II, Napoli, Italy
| | - Georg von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universitaet Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
| | - Smaragda Sotiraki
- Veterinary Research Institute, HAO-DEMETER, Campus Thermi 57001, Thessaloniki, Greece
| | - Manuela Schnyder
- Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
| | - Philip Skuce
- Moredun Research Institute, Pentlands Science Park, Edinburgh EH26 0PZ, UK
| | - David Bartley
- Moredun Research Institute, Pentlands Science Park, Edinburgh EH26 0PZ, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Edinburgh EH26 0PZ, UK
| | - Stig M Thamsborg
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Hannah Rose Vineer
- Institute of Infection and Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool, L3 5RF, UK; School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Theo de Waal
- University College Dublin, School of Veterinary Medicine, Belfield, Dublin, D04 W6F6, Ireland
| | - Andrew R Williams
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jan A van Wyk
- Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X20, Pretoria, South Africa
| | - Jozef Vercruysse
- Laboratory for Parasitology, Faculty of Veterinary Medicine, Ghent University, B9820 Merelbeke, Belgium
| |
Collapse
|
15
|
Albery GF, Kenyon F, Morris A, Morris S, Nussey DH, Pemberton JM. Seasonality of helminth infection in wild red deer varies between individuals and between parasite taxa. Parasitology 2018; 145:1410-1420. [PMID: 29519265 PMCID: PMC6137381 DOI: 10.1017/s0031182018000185] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/19/2018] [Accepted: 01/20/2018] [Indexed: 12/03/2022]
Abstract
Parasitism in wild mammals can vary according to myriad intrinsic and extrinsic factors, many of which vary seasonally. However, seasonal variation in parasitism is rarely studied using repeated samples from known individuals. Here we used a wild population of individually recognized red deer (Cervus elaphus) on the Isle of Rum to quantify seasonality and intrinsic factors affecting gastrointestinal helminth parasitism over the course of a year. We collected 1020 non-invasive faecal samples from 328 known individuals which we then analysed for propagules of three helminth taxa: strongyle nematodes, the common liver fluke Fasciola hepatica and the tissue nematode Elaphostrongylus cervi. Zero-inflated Poisson models were used to investigate how season, age and sex were associated with parasite prevalence and count intensity, while Poisson models were used to quantify individual repeatability within and between sampling seasons. Parasite intensity and prevalence varied according to all investigated factors, with opposing seasonality, age profiles and sex biases between parasite taxa. Repeatability was moderate, decreased between seasons and varied between parasites; both F. hepatica and E. cervi showed significant between-season repeatability, while strongyle nematode counts were only repeatable within-season and showed no repeatability within individuals across the year.
Collapse
Affiliation(s)
- Gregory F. Albery
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, EH26 0PZ, UK
| | - Alison Morris
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Sean Morris
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Daniel H. Nussey
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Josephine M. Pemberton
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
| |
Collapse
|
16
|
Morgan-Davies C, Lambe N, Wishart H, Waterhouse T, Kenyon F, McBean D, McCracken D. Impacts of using a precision livestock system targeted approach in mountain sheep flocks. Livest Sci 2018. [DOI: 10.1016/j.livsci.2017.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
17
|
Turnbull F, Jonsson NN, Kenyon F, Skuce PJ, Bisset SA. P-glycoprotein-9 and macrocyclic lactone resistance status in selected strains of the ovine gastrointestinal nematode, Teladorsagia circumcincta. Int J Parasitol Drugs Drug Resist 2018; 8:70-80. [PMID: 29414109 PMCID: PMC6114102 DOI: 10.1016/j.ijpddr.2018.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/05/2022]
Abstract
The Teladorsagia circumcincta P-glycoprotein-9 (Tci-pgp-9) gene has previously been implicated in multiple-anthelmintic resistance in this parasite. Here we further characterise genetic diversity in Tci-pgp-9 and its possible role in ivermectin (IVM) and multi-drug resistance using two UK field isolates of T. circumcincta, one susceptible to anthelmintics (MTci2) and the other resistant to most available anthelmintics including IVM (MTci5). A comparison of full-length Tci-pgp-9 cDNA transcripts from the MTci2 and MTci5 isolates (∼3.8 kb in both cases) indicated that they shared 95.6% and 99.5% identity at the nucleotide and amino acid levels, respectively. Nine non-synonymous SNPs were found in the MTci5 sequences relative to their MTci2 counterparts. Twelve genomic sequence variants of the first internucleotide binding domain of Tci-pgp-9 were identified and up to 10 of these were present in some individual worms, strongly supporting previous evidence that amplification of this gene has occurred in T. circumcincta. On average, fewer distinct sequence variants of Tci-pgp-9 were present in individual worms of the MTci5 isolate than in those of the MTci2 isolate. A further reduction in the number of sequence variants was observed in individuals derived from an IVM-treated sub-population of MTci5. These findings suggest that Tci-pgp-9 was under purifying selection in the face of IVM treatment in T. circumcincta, with some sequence variants being selected against. Tci-pgp-9 cDNA sequences from the MTci2 and MTci5 isolates shared 95.6% identity. Comparison of Tci-pgp-9 sequences from MTci5 and MTci2 showed 9 non-synonymous SNPs. Multiple Tci-pgp-9-IBDA sequence variants occurred in the majority of individual larvae. Tci-pgp-9 appears to be under purifying selection after anthelmintics are applied.
Collapse
Affiliation(s)
- Frank Turnbull
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom; Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
| | - Nicholas N Jonsson
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom
| | - Philip J Skuce
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom
| | - Stewart A Bisset
- AgResearch, Hopkirk Research Institute, Palmerston North, 4442, New Zealand
| |
Collapse
|
18
|
Charlier J, Thamsborg SM, Bartley DJ, Skuce PJ, Kenyon F, Geurden T, Hoste H, Williams AR, Sotiraki S, Höglund J, Chartier C, Geldhof P, van Dijk J, Rinaldi L, Morgan ER, von Samson-Himmelstjerna G, Vercruysse J, Claerebout E. Mind the gaps in research on the control of gastrointestinal nematodes of farmed ruminants and pigs. Transbound Emerg Dis 2017; 65 Suppl 1:217-234. [PMID: 29124904 DOI: 10.1111/tbed.12707] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Indexed: 12/31/2022]
Abstract
Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow-up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face of ongoing spread of anthelmintic resistance (AR), we are increasingly faced with a failure of existing control methods against GI nematodes. Effective vaccines against GI nematodes are generally not available, and anthelmintic treatment will therefore remain a cornerstone for their effective control. At the same time, consumers and producers are increasingly concerned with environmental issues associated with chemical parasite control. To address current challenges in GI nematode control, it is crucial to deepen our insights into diverse aspects of epidemiology, AR, host immune mechanisms and the socio-psychological aspects of nematode control. This will enhance the development, and subsequent uptake, of the new diagnostics, vaccines, pharma-/nutraceuticals, control methods and decision support tools required to respond to the spread of AR and the shifting epidemiology of GI nematodes in response to climatic, land-use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio-psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create an innovation-supportive environment for industries and to accelerate the access to market of new control tools.
Collapse
Affiliation(s)
- J Charlier
- Kreavet, Kruibeke, Belgium.,Avia-GIS, Zoersel, Belgium
| | - S M Thamsborg
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg C, Denmark
| | | | - P J Skuce
- Moredun Research Institute, Edinburgh, UK
| | - F Kenyon
- Moredun Research Institute, Edinburgh, UK
| | | | - H Hoste
- UMR IHAP 1225, INRA, ENVT, Université de Toulouse, Toulouse, France
| | - A R Williams
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg C, Denmark
| | - S Sotiraki
- VetResInst, HAO-DEMETER, Thessaloniki, Greece
| | - J Höglund
- BVF, Section for Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - P Geldhof
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - J van Dijk
- Institute of Infection and Global Health, University of Liverpool, Neston, Cheshire, UK
| | - L Rinaldi
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Napoli, Italy
| | - E R Morgan
- Institute for Global Food Security, Queen's University Belfast, Belfast, UK.,School of Veterinary Science, University of Bristol, North Somerset, UK
| | | | - J Vercruysse
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Claerebout
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| |
Collapse
|
19
|
Abstract
Parasitic roundworm infections are ubiquitous in grazing livestock. Chemical control through the frequent 'blanket' administration of anthelmintics (wormers) has been, and remains, the cornerstone in controlling these infections, but this practice is unsustainable. Alternative strategies are available but, even with the plethora of best practice advice available, have yet to be integrated into routine farming practice. This is probably due to a range of factors, including contradictory advice from different sources, changes to advice following increased scientific understanding, and top-down knowledge exchange patterns. In this article, we discuss the worm control options available, the translation of new best practice advice from science bench to field, and ideas for future work and directions.
Collapse
|
20
|
McBean D, Nath M, Kenyon F, Zile K, Bartley DJ, Jackson F. Faecal egg counts and immune markers in a line of Scottish Cashmere goats selected for resistance to gastrointestinal nematode parasite infection. Vet Parasitol 2016; 229:1-8. [DOI: 10.1016/j.vetpar.2016.08.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 11/28/2022]
|
21
|
Sinclair R, Melville L, Sargison F, Kenyon F, Nussey D, Watt K, Sargison N. Gastrointestinal nematode species diversity in Soay sheep kept in a natural environment without active parasite control. Vet Parasitol 2016; 227:1-7. [DOI: 10.1016/j.vetpar.2016.07.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/15/2016] [Accepted: 07/16/2016] [Indexed: 11/25/2022]
|
22
|
Melville LA, McBean D, Fyfe A, Campbell SJ, Palarea-Albaladejo J, Kenyon F. Effect of anthelmintic treatment strategy on strongylid nematode species composition in grazing lambs in Scotland. Parasit Vectors 2016; 9:199. [PMID: 27067011 PMCID: PMC4828790 DOI: 10.1186/s13071-016-1493-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/03/2016] [Indexed: 11/10/2022] Open
Abstract
Background Refugia 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). Methods Lambs 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. Results Results 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. Conclusion The 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.
Collapse
Affiliation(s)
- Lynsey A Melville
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, UK.
| | - David McBean
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, UK
| | - Alex Fyfe
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, UK
| | - Sara-Jane Campbell
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, UK
| | - Javier Palarea-Albaladejo
- Biomathematics and Statistics Scotland, The King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, Scotland, UK
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, UK
| |
Collapse
|
23
|
McBean D, Nath M, Lambe N, Morgan-Davies C, Kenyon F. Viability of the Happy Factor™ targeted selective treatment approach on several sheep farms in Scotland. Vet Parasitol 2016; 218:22-30. [DOI: 10.1016/j.vetpar.2016.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 01/05/2023]
|
24
|
Charlier J, Morgan ER, Rinaldi L, van Dijk J, Demeler J, Höglund J, Hertzberg H, Van Ranst B, Hendrickx G, Vercruysse J, Kenyon F. Practices to optimise gastrointestinal nematode control on sheep, goat and cattle farms in Europe using targeted (selective) treatments. Vet Rec 2015; 175:250-5. [PMID: 25217603 DOI: 10.1136/vr.102512] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Due to the development of anthelmintic resistance, there have been calls for more sustainable nematode control practices. Two important concepts were introduced to study and promote the sustainable use of anthelmintics: targeted treatments (TT), where the whole flock/herd is treated based on knowledge of the risk, or parameters that quantify the severity of infection; and targeted selective treatments (TST), where only individual animals within the grazing group are treated. The aim of the TT and TST approaches is to effectively control nematode-induced production impacts while preserving anthelmintic efficacy by maintaining a pool of untreated parasites in refugia. Here, we provide an overview of recent studies that assess the use of TT/TST against gastrointestinal nematodes in ruminants and investigate the economic consequences, feasibility and knowledge gaps associated with TST. We conclude that TT/TST approaches are ready to be used and provide practical benefits today. However, a major shift in mentality will be required to make these approaches common practice in parasite control.
Collapse
Affiliation(s)
- J Charlier
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - E R Morgan
- School of Veterinary Science, University of Bristol, Langford House, Langford, North Somerset BS40 5DU, UK
| | - L Rinaldi
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - J van Dijk
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Leahurst, Neston, Cheshire CH64 7TE, UK
| | - J Demeler
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag Strasse 7-13, 14163 Berlin, Germany
| | - J Höglund
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, PO Box 7063, Uppsala, Sweden
| | - H Hertzberg
- Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
| | - B Van Ranst
- Dairy DataWarehouse, Uniform-Agri BV, Oostersingel 23, Assen, The Netherlands
| | - G Hendrickx
- Avia-GIS, Agro-Veterinary Information and Analysis, Risschotlei 33, 2980 Zoersel, Belgium
| | - J Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - F Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK
| |
Collapse
|
25
|
Charlier J, van der Voort M, Kenyon F, Skuce P, Vercruysse J. Chasing helminths and their economic impact on farmed ruminants. Trends Parasitol 2014; 30:361-7. [PMID: 24888669 DOI: 10.1016/j.pt.2014.04.009] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 01/09/2023]
Abstract
Global agriculture will be required to intensify production from a shrinking natural resource base. Helminth infections of ruminants are a major constraint on efficient livestock production. The current challenge is to develop diagnostic methods that detect the production impact of helminth infections on farms in order to target control measures and contribute to the global challenge of preserving food security. We review here our understanding of the effects of helminth infections and control practices on productivity and the diagnostic tools that can inform on this. By combining advances in helminth laboratory diagnostics and animal health economics, sustainable management of helminth infections can be integrated into the whole-farm economic context.
Collapse
Affiliation(s)
- Johannes Charlier
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - Mariska van der Voort
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Social Sciences Unit, Institute for Agricultural and Fisheries Research (ILVO), Burgemeester Van Gansberghelaan 115, 9820 Merelbeke, Belgium; Department of Agricultural Economics, Faculty of Bio-Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK
| | - Philip Skuce
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| |
Collapse
|
26
|
Busin V, Kenyon F, Parkin T, McBean D, Laing N, Sargison N, Ellis K. Production impact of a targeted selective treatment system based on liveweight gain in a commercial flock. Vet J 2014; 200:248-52. [DOI: 10.1016/j.tvjl.2014.02.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 01/27/2014] [Accepted: 02/09/2014] [Indexed: 11/29/2022]
|
27
|
Busin V, Kenyon F, Laing N, Denwood M, McBean D, Sargison N, Ellis K. Addressing sustainable sheep farming: Application of a targeted selective treatment approach for anthelmintic use on a commercial farm. Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.11.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
28
|
Burgess STG, Downing A, Watkins CA, Marr EJ, Nisbet AJ, Kenyon F, McNair C, Huntley JF. Development of a cDNA microarray for the measurement of gene expression in the sheep scab mite Psoroptes ovis. Parasit Vectors 2012; 5:30. [PMID: 22316180 PMCID: PMC3296576 DOI: 10.1186/1756-3305-5-30] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/08/2012] [Indexed: 03/14/2023] Open
Abstract
Background Sheep scab is caused by the ectoparasitic mite Psoroptes ovis which initiates a profound cutaneous inflammatory response, leading to the development of the skin lesions which are characteristic of the disease. Existing control strategies rely upon injectable endectocides and acaricidal dips but concerns over residues, eco-toxicity and the development of acaricide resistance limit the sustainability of this approach. In order to identify alternative means of disease control, a deeper understanding of both the parasite and its interaction with the host are required. Methods Herein we describe the development and utilisation of an annotated P. ovis cDNA microarray containing 3,456 elements for the measurement of gene expression in this economically important ectoparasite. The array consists of 981 P. ovis EST sequences printed in triplicate along with 513 control elements. Array performance was validated through the analysis of gene expression differences between fed and starved P. ovis mites. Results Sequences represented on the array include homologues of major house dust mite allergens and tick salivary proteins, along with factors potentially involved in mite reproduction and xenobiotic metabolism. In order to validate the performance of this unique resource under biological conditions we used the array to analyse gene expression differences between fed and starved P. ovis mites. These analyses identified a number of house dust mite allergen homologues up-regulated in fed mites and P. ovis transcripts involved in stress responses, autophagy and chemosensory perception up-regulated in starved mites. Conclusion The P. ovis cDNA microarray described here has been shown to be both robust and reproducible and will enable future studies to analyse gene expression in this important ectoparasite.
Collapse
Affiliation(s)
- Stewart T G Burgess
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, Midlothian EH26 0PZ, UK.
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Burgess STG, Innocent G, Nunn F, Frew D, Kenyon F, Nisbet AJ, Huntley JF. The use of a Psoroptes ovis serodiagnostic test for the analysis of a natural outbreak of sheep scab. Parasit Vectors 2012; 5:7. [PMID: 22233730 PMCID: PMC3266638 DOI: 10.1186/1756-3305-5-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 01/10/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes ovis. The disease is endemic in the UK and has significant economic impact through its effects on performance and welfare. Diagnosis of sheep scab is achieved through observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in disease spread. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and limiting spread. METHODS Serum samples were obtained from an outbreak of sheep scab within an experimental flock (n = 480 (3 samples each from 160 sheep)) allowing the assessment, by ELISA of sheep scab specific antibody prior to infestation, mid-outbreak (combined with clinical assessment) and post-treatment. RESULTS Analysis of pre-infestation samples demonstrated low levels of potential false positives (3.8%). Of the 27 animals with clinical or behavioural signs of disease 25 tested positive at the mid-outbreak sampling period, however, the remaining 2 sheep tested positive at the subsequent sampling period. Clinical assessment revealed the absence of clinical or behavioural signs of disease in 132 sheep, whilst analysis of mid-outbreak samples showed that 105 of these clinically negative animals were serologically positive, representing potential sub-clinical infestations. CONCLUSIONS This study demonstrates that this ELISA test can effectively diagnose sheep scab in a natural outbreak of disease, and more importantly, highlights its ability to detect sub-clinically infested animals. This ELISA, employing a single recombinant antigen, represents a major step forward in the diagnosis of sheep scab and may prove to be critical in any future control program.
Collapse
Affiliation(s)
- Stewart T G Burgess
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, Midlothian, EH26 0PZ, Scotland, UK.
| | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
In Europe, most nematodoses are subclinical involving morbid rather than mortal effects and control is largely achieved using anthelmintics. In cattle, the genera most associated with sub-optimal performance are Ostertagia and Cooperia whereas in sheep and goats, subclinical losses are most often caused by Teladorsagia and Trichostrongylus. In some regions, at certain times, other species such as Nematodirus and Haemonchus also cause disease in sheep and goats. Unfortunately, anthelmintic resistance has now become an issue for European small ruminant producers. One of the key aims of the EU-funded PARASOL project was to identify low input and sustainable approaches to control nematode parasites in ruminants using refugia-based strategies. Two approaches to optimise anthelmintic treatments in sheep and cattle were studied; targeted treatments (TT) - whole-group treatments optimised on the basis of a marker of infection e.g. faecal egg count (FEC), and targeted selected treatment (TST) - treatments given to identified individuals to provide epidemiological and/or production benefits. A number of indicators for TT and TST were assessed to define parasitological and production-system specific indicators for treatment that best suited the regions where the PARASOL studies were conducted. These included liveweight gain, production efficiency, FEC, body condition score and diarrhoea score in small ruminants, and pepsinogen levels and Ostertagia bulk milk tank ELISA in cattle. The PARASOL studies confirmed the value of monitoring FEC as a means of targeting whole-flock treatments in small ruminants. In cattle, bulk milk tank ELISA and serum pepsinogen assays could be used retrospectively to determine the levels of exposure and hence, in the next season to optimise anthelmintic usage. TST approaches in sheep and goats examined production efficiency and liveweight gain as indicators for treatment and confirmed the value of this approach in maintaining performance and anthelmintic susceptibility in the predominant gastrointestinal nematodes. There is good evidence that the TST approach selected less heavily for the development of resistance in comparison to routine monthly treatments. Further research is required to optimise markers for TT and TST but it is also crucial to encourage producers/advisors to adapt these refugia-based strategies to maintain drug susceptible parasites in order to provide sustainable control.
Collapse
Affiliation(s)
- F Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh EH26 0PZ, Scotland, United Kingdom.
| | | |
Collapse
|
31
|
Burgess STG, Nisbet AJ, Kenyon F, Huntley JF. Generation, analysis and functional annotation of expressed sequence tags from the ectoparasitic mite Psoroptes ovis. Parasit Vectors 2011; 4:145. [PMID: 21781297 PMCID: PMC3154158 DOI: 10.1186/1756-3305-4-145] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 07/22/2011] [Indexed: 01/18/2023] Open
Abstract
Background Sheep scab is caused by Psoroptes ovis and is arguably the most important ectoparasitic disease affecting sheep in the UK. The disease is highly contagious and causes and considerable pruritis and irritation and is therefore a major welfare concern. Current methods of treatment are unsustainable and in order to elucidate novel methods of disease control a more comprehensive understanding of the parasite is required. To date, no full genomic DNA sequence or large scale transcript datasets are available and prior to this study only 484 P. ovis expressed sequence tags (ESTs) were accessible in public databases. Results In order to further expand upon the transcriptomic coverage of P. ovis thus facilitating novel insights into the mite biology we undertook a larger scale EST approach, incorporating newly generated and previously described P. ovis transcript data and representing the largest collection of P. ovis ESTs to date. We sequenced 1,574 ESTs and assembled these along with 484 previously generated P. ovis ESTs, which resulted in the identification of 1,545 unique P. ovis sequences. BLASTX searches identified 961 ESTs with significant hits (E-value < 1E-04) and 584 novel P. ovis ESTs. Gene Ontology (GO) analysis allowed the functional annotation of 880 ESTs and included predictions of signal peptide and transmembrane domains; allowing the identification of potential P. ovis excreted/secreted factors, and mapping of metabolic pathways. Conclusions This dataset currently represents the largest collection of P. ovis ESTs, all of which are publicly available in the GenBank EST database (dbEST) (accession numbers FR748230 - FR749648). Functional analysis of this dataset identified important homologues, including house dust mite allergens and tick salivary factors. These findings offer new insights into the underlying biology of P. ovis, facilitating further investigations into mite biology and the identification of novel methods of intervention.
Collapse
Affiliation(s)
- Stewart T G Burgess
- Division of Parasitology, Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, UK.
| | | | | | | |
Collapse
|
32
|
Demeler J, Küttler U, El-Abdellati A, Stafford K, Rydzik A, Varady M, Kenyon F, Coles G, Höglund J, Jackson F, Vercruysse J, von Samson-Himmelstjerna G. Standardization of the larval migration inhibition test for the detection of resistance to ivermectin in gastro intestinal nematodes of ruminants. Vet Parasitol 2010; 174:58-64. [DOI: 10.1016/j.vetpar.2010.08.020] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/30/2010] [Accepted: 08/16/2010] [Indexed: 10/19/2022]
|
33
|
Greer A, Kenyon F, Bartley D, Jackson E, Gordon Y, Donnan A, McBean D, Jackson F. Development and field evaluation of a decision support model for anthelmintic treatments as part of a targeted selective treatment (TST) regime in lambs. Vet Parasitol 2009; 164:12-20. [DOI: 10.1016/j.vetpar.2009.04.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
34
|
Burgess ST, Kenyon F, O’Looney N, Ross AJ, Kwan MC, Beattie JS, Petrik J, Ghazal P, Campbell CJ. A multiplexed protein microarray for the simultaneous serodiagnosis of human immunodeficiency virus/hepatitis C virus infection and typing of whole blood. Anal Biochem 2008; 382:9-15. [DOI: 10.1016/j.ab.2008.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 07/14/2008] [Accepted: 07/16/2008] [Indexed: 11/28/2022]
|
35
|
Nisbet AJ, Halliday AM, Parker L, Smith WD, Kenyon F, Knox DP, Huntley JF. Psoroptes ovis: Identification of vaccine candidates by immunoscreening. Exp Parasitol 2008; 120:194-9. [DOI: 10.1016/j.exppara.2008.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 06/19/2008] [Indexed: 10/21/2022]
|
36
|
Nassir E, Abdel-Muhsin AMA, Suliaman S, Kenyon F, Kheir A, Geha H, Ferguson HM, Walliker D, Babiker HA. Impact of genetic complexity on longevity and gametocytogenesis of Plasmodium falciparum during the dry and transmission-free season of eastern Sudan. Int J Parasitol 2004; 35:49-55. [PMID: 15619515 DOI: 10.1016/j.ijpara.2004.10.014] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 09/23/2004] [Accepted: 10/08/2004] [Indexed: 11/26/2022]
Abstract
Malaria in eastern Sudan is characterised by limited seasonal transmission, with the majority of the year remaining transmission-free. Some inhabitants who contract malaria during the transmission season retain long-lasting sub-patent infections, which probably initiate transmission the following year. Here we have monitored Plasmodium falciparum infection prevalence and gametocyte production during the dry season, and examined the impact of parasite genetic multiplicity on infection longevity. A cohort of 38 individuals who were infected with P. falciparum in November 2001 was monitored monthly by microscopy and PCR until December 2002. Reverse transcriptase polymerase chain reaction of the pfg377 gene was used to detect sub-patent gametocytes. In addition, all isolates were examined for msp-2 alleles and the mean number of parasite clones per infection was estimated. We found that a large proportion (40%) of the cohort retained gametocytes throughout the dry season. The majority of patients retained asexual infection for at least 7 months. Genetic multiplicity of P. falciparum significantly influenced longevity of asexual infection and its gametocyte production. Gametocytes from mixed genotype P. falciparum infections persisted three times longer than those from single genotype infections, suggesting that genetic diversity promotes persistence. These findings are discussed in the context of the parasite biology and malaria epidemiology in the study area.
Collapse
Affiliation(s)
- Elkhansaa Nassir
- Insititue of Cell Animal and Population Biology, Ashworth Laboratories, University of Edinburgh, West Mains Rd., Edinburgh, EH9 3JT, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Kenyon F, Welsh M, Parkinson J, Whitton C, Blaxter ML, Knox DP. Expressed sequence tag survey of gene expression in the scab mite Psoroptes ovis--allergens, proteases and free-radical scavengers. Parasitology 2003; 126:451-60. [PMID: 12793649 DOI: 10.1017/s0031182003003044] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Psoroptes ovis, the causative agent of sheep scab, is an important ectoparasitic mite infecting sheep, goats and cattle. Infection is characterized by an extensive dermatitis, scab formation and intense itching. Initial focal lesions spread outwards, coalesce and may extend over the whole body. The host response to infestation has all the characteristics of an immediate-type hypersensitivity reaction but the mite antigens and allergens which initiate this response are almost completely undefined. Here, 507 randomly selected cDNAs derived from a mixed population of P. ovis were sequenced and the resultant nucleotide sequences subjected to Cluster analysis and Blast searches. This analysis yielded 280 clusters of which 49 had > 1 sequence with 24 showing significant Blast X homology to another protein in the databases. There were 231 sequences which appeared on one occasion and 109 of these showed significant Blast X homology to other sequences in the databases. This analysis identified homologues of 9 different types of allergens which have been characterized in other allergic conditions such as responses to house dust mites. It also identified a number of cysteine proteases which may contribute to lesion development as well as several free-radical scavenging enzymes which may protect the mite from host immune effector responses.
Collapse
Affiliation(s)
- F Kenyon
- Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | | | | | | | | | | |
Collapse
|
38
|
Abstract
The sheep scab mite, Psoroptes ovis, causes severe dermatitis in infected sheep with severe welfare and production implications. The dermatitis has the characteristics of an immediate hypersensitivity type reaction which, by analogy to other mite species, including the house dust mites (Dermatophagoides spp.), is likely to be invoked by a variety of allergens including mite-derived proteinases. Here, the proteinases in P. ovis extracts were characterised using substrate gel analysis, inhibitor sensitivity and their ability to degrade a variety of potential natural protein substrates. These analyses showed that mites contain several proteinases which could be differentiated on the basis of molecular size and inhibitor sensitivity with cysteine, metalloproteinases and aspartyl proteinases predominating. These proteinases degraded collagen and fibronectin, possibly indicative of a role in lesion initiation, they degraded several blood proteins, a property which may aid mite feeding and they degraded immunoglobulin G, possibly aiding immuno-evasion. Because proteinases, particularly the cysteine class, are demonstrably allergenic in other mite infestations, these proteinases clearly merit further immunological and biochemical definition.
Collapse
Affiliation(s)
- Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | | |
Collapse
|