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Yan X, He S, Liu Y, Han B, Zhang N, Deng H, Wang Y, Liu M. Molecular identification and phylogenetic analysis of gastrointestinal nematodes in different populations of Kazakh sheep. Exp Parasitol 2023; 254:108625. [PMID: 37769836 DOI: 10.1016/j.exppara.2023.108625] [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: 12/09/2022] [Revised: 08/26/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Gastrointestinal nematode (GIN) infection in sheep has been recognized globally as a major problem challenging animal health and production. The objective of this study is to use a molecular diagnosis of the prevalence for gastrointestinal nematode (GIN) dominant species of Kazakh sheep and its hybrid (Kazakh × Texel). The internal transcribed spacer 2 (ITS-2) sequences of ribosomal DNA (rDNA) were used as the target sequence. In the study, three dominant species of nematodes, namely Haemonchus contortus, Trichostrongylus spp., and Teladorsagia (Ostertagia) circumcincta from the Kazakh sheep and the F1 and F2 generations of Texel × Kazakh sheep hybrids were subjected to molecular identification and phylogenetic analysis. The fecal and single larva genomic DNA were extracted and amplified by PCR using specific primers to determine the infection rate of the three nematode species. In addition, the PCR products were sequenced and analyzed using bioinformatics methods to construct a phylogenetic tree. The results showed that all the three species had their ITS-2 specific amplified. According to the sequence homology analysis of PCR products, the results showed a high homology (above 98.5% homology) with H. contortus, Trichostrongylus spp., T. circumcincta ITS-2 sequences in GenBank. Phylogenetic analysis showed that the ITS-2 sequences of the three species were on the same branch as the ITS-2 sequences of the same species in NCBI. And on different branches from those of the ITS-2 sequences of different families, genera and species. Sequences carried out on three species from different samples showed a close relationship and little genetic difference in phylogenetic tree. The infection rates based on fecal DNA were 35.59, 25.55, and 11.24% for H. contortus, Trichostrongylus spp., and T. circumcincta, respectively. While the infection rates based on larva DNA, were 24.07, 18.89, and 13.26% for H. contortus, Trichostrongylus spp., and T. circumcincta, respectively. The seasonal prevalence of the three dominant species in spring was significantly higher than that in autumn and winter. And there was no significant difference between Kazakh, F1 and F2 sheep considering the infection rate of the studied three species of nematodes. This study provides valuable molecular approaches for epidemiological surveillance and for assisting in the control of Nematodirus infection in sheep.
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Affiliation(s)
- Xiaofei Yan
- College of Life Sciences, Xinjiang Agricultural University, Urumqi, 830052, China
| | - Sangang He
- Institute of Biotechnology, Xinjiang Academy of Animal Science, Key Laboratory of Genetic Breeding and Reproduction of Herbivorous Livestock of Ministry of Agriculture, Xinjiang Key Laboratory of Animal Biotechnology, Urumqi, Xinjiang Province, China
| | - Yiyong Liu
- Animal Husbandry, Terminus of Ili Kazakh Autonomous Prefecture, Yining, Xinjiang Province, China
| | - Bing Han
- Institute of Biotechnology, Xinjiang Academy of Animal Science, Key Laboratory of Genetic Breeding and Reproduction of Herbivorous Livestock of Ministry of Agriculture, Xinjiang Key Laboratory of Animal Biotechnology, Urumqi, Xinjiang Province, China
| | - Ning Zhang
- Institute of Biotechnology, Xinjiang Academy of Animal Science, Key Laboratory of Genetic Breeding and Reproduction of Herbivorous Livestock of Ministry of Agriculture, Xinjiang Key Laboratory of Animal Biotechnology, Urumqi, Xinjiang Province, China
| | - Haifeng Deng
- Zhaosu Horse Farm, Ili Kazakh Autonomous Prefecture, Zhaosu, Xinjiang Province, China
| | - Yuqi Wang
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, 830052, China
| | - Mingjun Liu
- Institute of Biotechnology, Xinjiang Academy of Animal Science, Key Laboratory of Genetic Breeding and Reproduction of Herbivorous Livestock of Ministry of Agriculture, Xinjiang Key Laboratory of Animal Biotechnology, Urumqi, Xinjiang Province, China.
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Ahmed N, Roy BC, Hasan MM, Zim MMR, Biswas H, Talukder MH. Molecular and phylogenetic characterization of zoonotic Trichostrongylus species from goats for the first time in Bangladesh. Trans R Soc Trop Med Hyg 2023; 117:705-713. [PMID: 37309997 DOI: 10.1093/trstmh/trad034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 03/30/2023] [Accepted: 05/18/2023] [Indexed: 06/14/2023] Open
Abstract
BACKGROUND Trichostrongylus is one of the most important nematodes infecting animals and humans. The current study was designed to identify the Trichostrongylus species infecting goats by multiplex PCR and phylogenetic analysis. METHODS A total of 124 goats' viscera were collected from different abattoirs of Mymensingh division. Trichostrongylus species were isolated and characterized based on morphometry, multiplex PCR and phylogenetic analysis. RESULTS Among 124 viscera of goats, 39 were positive with two species, Trichostrongylus colubriformis and Trichostrongylus vitrinus, revealing an overall 31.45% prevalence. Morphological identification of Trichostrongylus species was confirmed by multiplex PCR amplification of the ITS2 gene and sequencing. Partial sequencing of the ITS2 gene of two species revealed seven single nucleotide polymorphisms (three transitions and four transversions) in this study. The neighbor-joining phylogenetic tree demonstrated that T. colubriformis and T. vitrinus isolates were clustered together with the reference sequences that belong to the clade A and B without any geographical boundaries. CONCLUSIONS This is the first report on molecular and phylogenetic analysis of Trichostrongylus species from ruminants in Bangladesh. These results provide the baseline data for understanding the zoonosis and epidemiology of this parasite in Bangladesh and global perspectives.
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Affiliation(s)
- Nurnabi Ahmed
- Department of Parasitology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
| | - Babul Chandra Roy
- Department of Parasitology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
| | | | | | - Hiranmoy Biswas
- Department of Parasitology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
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Davey ML, Kamenova S, Fossøy F, Solberg EJ, Davidson R, Mysterud A, Rolandsen CM. Faecal metabarcoding provides improved detection and taxonomic resolution for non-invasive monitoring of gastrointestinal nematode parasites in wild moose populations. Parasit Vectors 2023; 16:19. [PMID: 36653864 PMCID: PMC9847159 DOI: 10.1186/s13071-022-05644-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 12/28/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Although wild ungulate populations are heavily monitored throughout Europe, we understand little of how parasites affect population dynamics, and there is no systematic, long-term monitoring of parasite diversity and parasite loads. Such monitoring is in part hampered by a lack of time- and cost-effective assay methodologies with high sensitivity and good taxonomic resolution. DNA metabarcoding has been successfully used to characterize the parasitic nemabiome with high taxonomic resolution in a variety of wild and domestic hosts. However, in order to implement this technique in large-scale, potentially non-invasive monitoring of gastrointestinal parasitic nematodes (GIN), protocol optimization is required to maximize biodiversity detection, whilst maintaining time- and cost-effectiveness. METHODS Faecal samples were collected from a wild moose population and GIN communities were characterized and quantified using both parasitological techniques (egg and larva counting) and DNA metabarcoding of the ITS2 region of rDNA. Three different isolation methods were compared that differed in the volume of starting material and cell lysis method. RESULTS Similar nematode faunas were recovered from all samples using both parasitological and metabarcoding methods, and the approaches were largely congruent. However, metabarcoding assays showed better taxonomic resolution and slightly higher sensitivity than egg and larvae counts. The metabarcoding was not strictly quantitative, but the proportion of target nematode sequences recovered was correlated with the parasitologically determined parasite load. Species detection rates in the metabarcoding assays were maximized using a DNA isolation method that included mechanical cell disruption and maximized the starting material volume. CONCLUSIONS DNA metabarcoding is a promising technique for the non-invasive, large-scale monitoring of parasitic GINs in wild ungulate populations, owing to its high taxonomic resolution, increased assay sensitivity, and time- and cost-effectiveness. Although metabarcoding is not a strictly quantitative method, it may nonetheless be possible to create a management- and conservation-relevant index for the host parasite load from this data. To optimize the detection rates and time- and cost-effectiveness of metabarcoding assays, we recommend choosing a DNA isolation method that involves mechanical cell disruption and maximizes the starting material volume.
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Affiliation(s)
- Marie L. Davey
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - Stefaniya Kamenova
- grid.5510.10000 0004 1936 8921University of Oslo, Oslo, Norway ,grid.19477.3c0000 0004 0607 975XNorwegian University of Life Sciences, Ås, Norway
| | - Frode Fossøy
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - Erling J. Solberg
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - Rebecca Davidson
- grid.410549.d0000 0000 9542 2193Norwegian Veterinary Institute, Tromsø, Norway
| | - Atle Mysterud
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), Trondheim, Norway ,grid.5510.10000 0004 1936 8921University of Oslo, Oslo, Norway
| | - Christer M. Rolandsen
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), Trondheim, Norway
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Diagnosis of Oestrus ovis infestation in sheep by PCR and enzyme-linked immunosorbent assay. Vet Parasitol 2022; 310:109789. [DOI: 10.1016/j.vetpar.2022.109789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 08/04/2022] [Accepted: 08/23/2022] [Indexed: 11/24/2022]
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Rinaldi L, Krücken J, Martinez-Valladares M, Pepe P, Maurelli MP, de Queiroz C, Castilla Gómez de Agüero V, Wang T, Cringoli G, Charlier J, Gilleard JS, von Samson-Himmelstjerna G. Advances in diagnosis of gastrointestinal nematodes in livestock and companion animals. ADVANCES IN PARASITOLOGY 2022; 118:85-176. [PMID: 36088084 DOI: 10.1016/bs.apar.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Diagnosis of gastrointestinal nematodes in livestock and companion animals has been neglected for years and there has been an historical underinvestment in the development and improvement of diagnostic tools, undermining the undoubted utility of surveillance and control programmes. However, a new impetus by the scientific community and the quickening pace of technological innovations, are promoting a renaissance of interest in developing diagnostic capacity for nematode infections in veterinary parasitology. A cross-cutting priority for diagnostic tools is the development of pen-side tests and associated decision support tools that rapidly inform on the levels of infection and morbidity. This includes development of scalable, parasite detection using artificial intelligence for automated counting of parasitic elements and research towards establishing biomarkers using innovative molecular and proteomic methods. The aim of this review is to assess the state-of-the-art in the diagnosis of helminth infections in livestock and companion animals and presents the current advances of diagnostic methods for intestinal parasites harnessing (i) automated methods for copromicroscopy based on artificial intelligence, (ii) immunodiagnosis, and (iii) molecular- and proteome-based approaches. Regardless of the method used, multiple factors need to be considered before diagnostics test results can be interpreted in terms of control decisions. Guidelines on how to apply diagnostics and how to interpret test results in different animal species are increasingly requested and some were recently made available in veterinary parasitology for the different domestic species.
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Affiliation(s)
- Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy.
| | - J Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
| | - M Martinez-Valladares
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, León, Spain
| | - P Pepe
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | - M P Maurelli
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | - C de Queiroz
- Faculty of Veterinary Medicine, 3331 Hospital Drive, Host-Parasite Interactions (HPI) Program University of Calgary, Calgary, Alberta, Canada; Faculty of Veterinary Medicine, St Georges University, Grenada
| | - V Castilla Gómez de Agüero
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, León, Spain
| | - T Wang
- Kreavet, Kruibeke, Belgium
| | - Giuseppe Cringoli
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | | | - J S Gilleard
- Faculty of Veterinary Medicine, 3331 Hospital Drive, Host-Parasite Interactions (HPI) Program University of Calgary, Calgary, Alberta, Canada
| | - G von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
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Sarah A, Khanal P, Holler LD, Holler SW, Hildreth MB. Extended effects of an aggressive spring-time anthelmintic treatment on Haemonchus contortus in sheep from a North America cold winter climate. Small Rumin Res 2022. [DOI: 10.1016/j.smallrumres.2021.106568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Maurizio A, Frangipane di Regalbono A, Cassini R. Quantitative Monitoring of Selected Groups of Parasites in Domestic Ruminants: A Comparative Review. Pathogens 2021; 10:1173. [PMID: 34578205 PMCID: PMC8467286 DOI: 10.3390/pathogens10091173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/07/2021] [Accepted: 09/09/2021] [Indexed: 11/28/2022] Open
Abstract
Parasites have had a significant impact on domestic ruminant health and production for a long time, but the emerging threat of drug resistance urgently requires an improved approach to parasite monitoring and control activities. The study reviewed the international literature to analyze the different proposals for the sampling approach and the quantitative estimation of parasite burdens in groups of animals. Moreover, the use of thresholds to decide when and which animal to treat was also investigated. The findings of the study highlighted the presence of a wide-ranging literature on quantitative monitoring for gastrointestinal nematodes (GIN), while more limited data were found for coccidia, and no specific indications were reported for tapeworms. Concerning liver flukes, bronchopulmonary nematodes (BPN) and permanent ectoparasites (lice and mange mites), the diagnostic process is usually aimed at the detection of the parasite rather than at the burden estimation. The main research gaps that need further investigation were also highlighted. For some groups of parasites (e.g., GIN and coccidia) the quantitative approach requires an improved standardization, while its usefulness needs to be confirmed for others (e.g., BPN and lice). The development of practical guidelines for monitoring is also encouraged.
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Affiliation(s)
| | | | - Rudi Cassini
- Department of Animal Medicine, Production and Health, University of Padova, Viale dell’Università, 16-35020 Legnaro, Italy; (A.M.); (A.F.d.R.)
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Reslova N, Skorpikova L, Kyrianova IA, Vadlejch J, Höglund J, Skuce P, Kasny M. The identification and semi-quantitative assessment of gastrointestinal nematodes in faecal samples using multiplex real-time PCR assays. Parasit Vectors 2021; 14:391. [PMID: 34372893 PMCID: PMC8351436 DOI: 10.1186/s13071-021-04882-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/20/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The diagnosis of gastrointestinal nematode (GIN) infections in ruminants is routinely based on morphological/morphometric analysis of parasite specimens recovered by coprological methods, followed by larval culture (LC) techniques. Such an approach is laborious, time-consuming, requires a skilled expert, and moreover suffers from certain limitations. Molecular tools are able to overcome the majority of these issues, providing accurate identification of nematode species and, therefore, may be valuable in sustainable parasite control strategies. METHODS Two multiplex real-time polymerase chain reaction (PCR) assays for specific detection of five main and one invasive GIN species, including an internal amplification control to avoid false-negative results, were designed targeting SSU rRNA and COI genetic markers, as well as established ITS1/2 sequences. The assays were optimized for analysis of DNA extracted directly from sheep faeces and verified for Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis, Nematodirus battus, Chabertia ovina, and Ashworthius sidemi. Semi-quantitative evaluation of infection intensity was enabled using a plasmid construct and a dilution series of sheep faeces with a known number of nematode eggs. Assays were tested on 44 individually collected faecal samples from three farms, and results were compared to those from faecal egg counts (FEC) using the concentration McMaster technique and LC. RESULTS Multiplex real-time PCR assays showed great specificity to target nematodes. During the analysis of faecal samples, the assays proved to have higher sensitivity in strongylid-type egg detection over FEC by revealing three false-negative samples, while showing moderate agreement in evaluation of infection intensity. The multiplex assays further clarified GIN species identification compared to LC, which had confused determination of Teladorsagia spp. for Trichostrongylus spp. CONCLUSIONS Our multiplex assays proved to be a rapid and accurate approach enabling simultaneous and reliable GIN species identification from faeces and semi-quantitative estimation of the number of eggs present. This approach increases diagnostic value and may add a high degree of precision to evaluation of anthelmintic efficacy, where it is important to identify species surviving after treatment.
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Affiliation(s)
- Nikol Reslova
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic.
| | - Lucie Skorpikova
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Iveta Angela Kyrianova
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
| | - Jaroslav Vadlejch
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
| | - Johan Höglund
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Philip Skuce
- Moredun Research Institute, Pentlands Science Park, Edinburgh, UK
| | - Martin Kasny
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
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Saleh S, Abbas I, Al-Araby M, Hildreth M, Abu-Elwafa S. Combined Molecular and Lectin Binding Assays to Identify Different Trichostrongyle Eggs in Feces of Sheep and Goats from Egypt. Acta Parasitol 2021; 66:384-396. [PMID: 33034823 DOI: 10.1007/s11686-020-00287-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 09/22/2020] [Indexed: 10/22/2022]
Abstract
BACKGROUND Trichostrongyles are common causes of parasitic gastroenteritis in sheep and goats worldwide. Accurate identification of these nematodes to the genus and/or species level is important for therapy selection and control strategies. In the present study, molecular and egg-lectin binding approaches were employed to identify the most economically important trichostrongyles circulating in sheep and goat herds from six districts in Dakahlia governorate, Egypt. MATERIALS Fecal samples from 653 and 205 goats reared within 17 herds were collected and tested for the trichostrongyle eggs using the modified Wisconsin sucrose flotation method. For identification of the trichostrongyle(s) present, eggs from 75 (63 sheep and 12 goats) samples which had high egg count (EPG) and pooled eggs (n = 19 pools, 15 sheep and 4 goats) from samples with moderate or low EPGs were examined. Molecular examination was conducted amplifying the ITS2 region of the rDNA for six different trichostrongyles in individual PCR reactions. For egg-lectin bindings, 4 fluorescently-labeled specific lectins were used; peanut agglutinin (PNA) for Haemonchus contortus, Aleuria aurantia agglutinin (AAL) for Trichostrongylus species, Lens culinaris agglutinin (LCA) for Teladorsagia circumcnicta and Lotus tetragonolobus lectin (LTL) for Cooperia species. RESULTS Fourteen (82.3%) herds were found infected, of which trichostrongyle eggs were detected in fecal samples of 26.5% (173/653) of sheep and 10.2% (21/205) of goats. Results of the PCR and lectin bindings were compatible and 4 trichostrongyles were detected: H. contortus, T. circumcincta, Trichostrongylus axei and Trichostrongylus colubriformis. Haemonchus contortus eggs were found in all the infected herds, and as the single species in 21 and 5 of sheep and goat samples, respectively. Lectin stained smears demonstrated the dominance of H. contortus eggs over eggs of the other detected trichostrongyles. Eleven herds were found infected with T. axei as the second most prevalent trichostrongyle; however, few AAL-stained eggs were noticed in the positive samples. Mixed infections were frequently detected as H. contortus-T. axei combination. Infections with T. circumcincta were noted in sheep samples from two herds, but not in any sample from the goats. No Ostertagia leptospicularis, Cooperia curticei or Nematodirus species were noted among the tested samples. CONCLUSIONS This is the first molecular and lectin binding survey to determine the species composition of trichostrongyles infecting sheep and goats from Egypt. Haemonchus contortus plays the principal role in small ruminant trichostrongylosis in Egypt. Egg-lectin staining shows promise for future for its application in routine diagnosis as a rapid and simple technique. Findings of the earlier reports from Egypt are tabulated and reviewed.
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Affiliation(s)
- Somaya Saleh
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516, Egypt
| | - Ibrahim Abbas
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516, Egypt.
| | - Moustafa Al-Araby
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516, Egypt
| | - Michael Hildreth
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA
| | - Salah Abu-Elwafa
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516, Egypt
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Arsenopoulos KV, Fthenakis GC, Katsarou EI, Papadopoulos E. Haemonchosis: A Challenging Parasitic Infection of Sheep and Goats. Animals (Basel) 2021; 11:ani11020363. [PMID: 33535656 PMCID: PMC7912824 DOI: 10.3390/ani11020363] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/23/2021] [Accepted: 01/29/2021] [Indexed: 12/12/2022] Open
Abstract
The paper reviews the challenges about haemonchosis-a significant and common parasitic infection of small ruminants. Haemonchus contortus is a highly pathogenic parasite that localises in the abomasum of affected animals and exerts its pathogenicity by blood-sucking activity, adversely affecting the health and productivity of animals. The first challenge is the uneven distribution of the infection globally, this being more prevalent in tropical and subtropical and warm temperate and summer rainfall regions than in cool and cold temperate and arid regions; hence, this leads in differences in the approaches required for its control. Another challenge is the widespread presence of Haemonchus strains resistant to the various anthelmintics available: Benzimidazoles, imidazothiazoles, macrocyclic lactones, closantel and monepantel, which makes the control of the infection difficult. The third challenge refers to the difficulty of diagnosing the disease, given that field evidence can provide suspicion about the infection, which needs to be subsequently confirmed by laboratory tests through parasitological or molecular techniques. The final challenge relates to the difficulties in the control of the infection and the necessity to use pharmaceutical products cautiously and with a planned approach, to avoid further development of anthelmintic resistance, also given that use of a recently licenced vaccine is not widespread. In conclusion, at the moment, we should be concerned, but not worried, about this infection, and apply correctly the appropriate health management plans.
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Affiliation(s)
- Konstantinos V. Arsenopoulos
- Laboratory of Parasitology and Parasitic Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
| | - George C. Fthenakis
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece; (G.C.F.); (E.I.K.)
| | - Eleni I. Katsarou
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece; (G.C.F.); (E.I.K.)
| | - Elias Papadopoulos
- Laboratory of Parasitology and Parasitic Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
- Correspondence:
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Elseadawy R, Abbas I, Al-Araby M, Abu-Elwafa S. Molecular identification of different Trichostrongylus species infecting sheep and goats from Dakahlia governorate, Egypt. J Parasit Dis 2020; 45:218-227. [PMID: 33746407 DOI: 10.1007/s12639-020-01299-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 10/21/2020] [Indexed: 11/24/2022] Open
Abstract
Nematodes of genus Trichostrongylus can cause remarkable economic losses in the small ruminant`s industry and some species have a zoonotic potential. Since the most common source for human infection is the infected animals, accurate identification of different Trichostrongylus species in animals would reflect the species that can infect humans from the same area. The objective of the present study is to identify common Trichostrongylus species infecting small ruminants in Dakahlia governorate, Egypt using molecular-based techniques. Fecal samples from 340 sheep and 115 goats from rural areas in 3 cities of Dakahlia governorate and 2 cities at its borders were collected, and the strongyle-type eggs were detected in 33.2% and 14.7% of sheep and goats, respectively. PCR amplification of the internal transcribed spacer of the ribosomal DNA (ITS2 rDNA) for 3 Trichostrongylus spp.; T. axei, T. colubriformis and T. vitrinus was conducted for eggs harvested from 25 sheep and 16 goat samples. Two species were detected; T. axei (in 16 sheep and 14 goats) and T. colubriformis (in 2 sheep but no goats). This is the first report of T. colubriformis in sheep from Dakahlia governorate, where this species was reported earlier from humans. No T. vitrinus was detected in any tested sample of sheep or goats. Purified PCR products of T. axei isolates were successfully sequenced and revealed 3 haplotypes; 2 from sheep and 1 from goats, and the isolates are related genetically to T. axei isolates from camels in Egypt. Phylogenetic analysis of the Genbank-retrieved ITS2-amplified T. axei isolates worldwide suggested the existence of genetic variants. Earlier reports on the identified Trichostrongylus spp. in different animals from Egypt as well as African and Arabian countries are tabulated.
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Affiliation(s)
- Rana Elseadawy
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516 Egypt
| | - Ibrahim Abbas
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516 Egypt
| | - Moustafa Al-Araby
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516 Egypt
| | - Salah Abu-Elwafa
- Parasitology Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516 Egypt
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Duzlu O, Yildirim A, Yetismis G, Onder Z, Simsek E, Ciloglu A, Demirpolat GS, Inci A. Development and field evaluation of a species-specific mt-COI targeted SYBR-Green Real Time PCR for detection and quantification of Haemonchus contortus in cattle in Turkey. Vet Parasitol 2019; 277:109020. [PMID: 31896019 DOI: 10.1016/j.vetpar.2019.109020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/18/2022]
Abstract
Haemonchus contortus is one of the most important gastrointestinal nematodes (GINs) infecting sheep, goats, and cattle worldwide. We developed a SYBR Green real-time PCR (qPCR) assay for detection and quantification of H. contortus by using specific primers based on a conserved region of the mitochondrial cytochrome oxidase subunit I (mt-COI) gene, and evaluated this technique in the detection of H. contortus infections in cattle in Central Anatolia Region of Turkey. The newly developed qPCR assay successfully discriminated H. contortus from other GIN species infecting cattle in the specificity evaluations, with a specific melt peak of 77.5 °C. Our results revealed the efficient amplification of the proposed target COI region within the range of plasmid copies, from 2 × 106 to 2 × 101 per μl, with 96.9 % efficiency, R² value of 0.999, and a slope of -3.398. Among the 920 cattle fecal samples from the field, 58 samples (6.3 %) were positive with qPCR assay, whereas 45 samples (4.9 %) were positive, as determined by larval culture, suggesting the utility of SYBR Green qPCR. Phylogenetic characterization of the partial COI gene of H. contortus isolates was also evaluated for 100 eggs and third stage larvae recovered from positive cattle faecal samples, which were verified with the qPCR assay prior to analyses. COI sequences were classified into three haplotypes (THC1 to THC3) with intraspecific nucleotide differences of 0.50 to 0.76 %. Phylogenetic analyses revealed that the haplotypes grouped with H. contortus isolates from several countries in a monophyletic cluster, with evidence of at least two main haplogroups. Overall, the SYBR Green qPCR assay was highly specific and sensitive, suggesting that it can be used for screening of H. contortus infections in livestock populations in epidemiological studies and the control of this important parasite.
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Affiliation(s)
- Onder Duzlu
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey.
| | - Alparslan Yildirim
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | - Gamze Yetismis
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | - Zuhal Onder
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | - Emrah Simsek
- Preclinical Sciences, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | - Arif Ciloglu
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | | | - Abdullah Inci
- Department of Parasitology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
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Molecular screening approach to identify protozoan and trichostrongylid parasites infecting one-humped camels (Camelus dromedarius). Acta Trop 2019; 197:105060. [PMID: 31194962 DOI: 10.1016/j.actatropica.2019.105060] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 12/19/2022]
Abstract
Little is known about the diversity of many parasites infecting camels, with most relying on morphological parameters. DNA extracted from different tissues (n = 90) and fecal samples (n = 101) from dromedary camels (Camelus dromedarius) in Egypt were screened for multiple parasites using different molecular markers. Screening of tissue samples (heart) for Toxoplasma gondii and Sarcocystis spp. was performed using B1 and 18S rRNA gene markers, respectively. T. gondii was further genotyped using multiplex multilocus nested PCR-RFLP (Mn-PCR-RFLP). Sarcocystis was analyzed using PCR-RFLP characterization (XbaI and MboI restriction enzymes). A taxonomically challenging but important group of nematodes (Trichostrongylidae family) were screened using the ITS-2 ribosomal DNA (rDNA) species-specific markers. Furthermore, nested PCR was used for the detection of Cryptosporidium spp. (SSU rRNA gene) and positive samples were genotyped after RFLP (SspI and VspI) and sequencing. Cryptosporidium parvum isolates were subtyped by sequence analysis of the 60-kDa glycoprotein gene. This study revealed that many parasites infect the investigated camels, including T. gondii (1.1%), Sarcocystis spp. (64.4%), Cryptosporidium spp. (5.9%) and Trichostrongylidae nematodes (22.7%). The species contribution for nematodes was as follows: Haemonchus spp. (95.6%), Trichostrongylus axei (26%), Trichostrongylus colubriformis (65.2%) and Cooperia oncophora (60.8%). Mn-PCR-RFLP typing for Toxoplasma was only successful for three markers: 5'-SAG2 (type II), 3'-SAG2 (type II) and alt. SAG2 (type II). PCR-RFLP using XbaI showed possible mixed Sarcocystis infection. Moreover, the Cryptosporidium genotypes detected were C. parvum (IIdA19G1 and IIaA15G1R1), Cryptosporidium rat genotype IV and a novel genotype (camel genotype). This approach revealed the unique Cryptosporidium genotypes infecting the investigated camels, and the high genetic diversity of the investigated parasites.
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Karshima SN, Maikai BV, Kwaga JKP. Helminths of veterinary and zoonotic importance in Nigerian ruminants: a 46-year meta-analysis (1970-2016) of their prevalence and distribution. Infect Dis Poverty 2018; 7:52. [PMID: 29807540 PMCID: PMC5972411 DOI: 10.1186/s40249-018-0438-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 05/09/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The livestock industry plays a vital role in the economy of Nigeria. It serves as a major source of income and livelihood for majority of Nigerians who are rural settlers and contributes about 5.2% to the National Gross Domestic Product (GDP). Helminths however, cause economic losses due to reductions in milk production, weight gain, fertility and carcass quality. Zoonotic helminths of livestock origin cause health problems in humans. METHODS Using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, the prevalence and distribution of helminths of veterinary and zoonotic importance in Nigerian ruminants were determined in a meta-analysis of data published between 1970 and 2016. Data were stratified based on regions, hosts, study periods, sample sizes and study types while helminths were phylogenetically grouped into cestodes, nematodes and trematodes. RESULTS Data from 44 studies reported across 19 Nigerian states revealed an overall pooled prevalence estimate (PPE) of 7.48% (95% CI: 7.38-7.57) for helminths of veterinary and zoonotic importance from a total of 320 208 ruminants. We observed a significant variation (P < 0.001) between the PPEs range of 1.90% (95% CI: 1.78-2.02) and 60.98% (95% CI: 58.37-63.55) reported across different strata. High heterogeneity (99.78, 95% CI: 7.38-7.57) was observed. Strongyloides papillosus was the most prevalent (Prev: 32.02%, 95% CI: 31.01-33.11), while, Fasciola gigantica had the widest geographical distribution. CONCLUSIONS Helminths of veterinary and zoonotic importance are prevalent in ruminants and well distributed across Nigeria. Our findings show that helminths of ruminants may also be possible causes of morbidity in humans and economic losses in the livestock industry in Nigeria. High heterogeneity was observed within studies and the different strata. Good agricultural practices on farms, standard veterinary meat inspection and adequate hygiene and sanitation in abattoirs, farms and livestock markets need to be implemented in Nigeria in order to reduce the economic, public health and veterinary threats due to these helminths.
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Affiliation(s)
- Solomon Ngutor Karshima
- Department of Veterinary Public Health and Preventive Medicine, University of Jos, PMB, 2084, Jos, Nigeria.
| | - Beatty-Viv Maikai
- Department of Veterinary Public Health and Preventive Medicine, Ahmadu Bello University, PMB, 1045, Zaria, Nigeria
| | - Jacob Kwada Paghi Kwaga
- Department of Veterinary Public Health and Preventive Medicine, Ahmadu Bello University, PMB, 1045, Zaria, Nigeria
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Jacobson C, Williams A, Yang R, Ryan U, Carmichael I, Campbell AJ, Gardner GE. Greater intensity and frequency of Cryptosporidium and Giardia oocyst shedding beyond the neonatal period is associated with reductions in growth, carcase weight and dressing efficiency in sheep. Vet Parasitol 2016; 228:42-51. [DOI: 10.1016/j.vetpar.2016.08.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 07/29/2016] [Accepted: 08/01/2016] [Indexed: 02/07/2023]
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Eljaki AA, Al Kappany YM, Grosz DD, Smart AJ, Hildreth MB. Molecular survey of trichostrongyle nematodes in a Bison bison herd experiencing clinical parasitism, and effects of avermectin treatment. Vet Parasitol 2016; 227:48-55. [PMID: 27523937 DOI: 10.1016/j.vetpar.2016.07.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 07/16/2016] [Accepted: 07/19/2016] [Indexed: 10/21/2022]
Abstract
North American bison (Bison bison) producers face many challenges, including the potential clinical and economics problems caused by trichostrongyle nematodes within their herds. Little is known about the prevalence, intensity, geographical distribution and clinical significance of these parasites in commercial bison herds, even from regions where bison production has become popular. This study involved a large herd of bison from eastern South Dakota that was experiencing clinical parasitism due to a temporary over-stocking problem. After documenting fecal egg counts (FECs) and trichostrongyle genera present among the 3 main age-categories (i.e. adults, yearlings, calves) of bison during this heavily infected grazing season, the effects of doramectin treatment on the different age groups was also evaluated. This is the first bison study using PCR to identify genera of trichostrongyles in fecal samples. Virtually all 103 bison fecal samples from all 3 age classes were shedding trichostrongyle eggs by the end of the season, and the mean FECs were 34 eggs/g (EPG) among the cows, 125 EPG in the yearlings, and 186 EGP among calves. Based upon this heavily-infected herd, there is evidence that the susceptibility of bison to trichostrongyles is more similar to beef cattle than to sheep. Other parasites such as Moniezia, Nematodirus, Trichuris, and coccidians were also identified in these samples. All but 3 of the 51 samples analyzed with PCR shown at least 1 trichostrongyle genera. Ostertagia was detected in 68.6% of the samples, Cooperia in 80.39%, Haemonchus in at least 73% and Trichostrongylus in 16% of the herd. Most commonly, bison were infected with combinations of Haemonchus/Ostertagia/Cooperia. After treatment with doramectin, the mean FECs dropped by 99.9% for all of the bison age classes.
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Affiliation(s)
- A A Eljaki
- Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States; Departments of Zoology, University of Omar Almukhtar, Al Bayda, Libya and University of Benghazi, Benghazi, Libya
| | - Y M Al Kappany
- Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States; Department of Parasitology. Faculty of Veterinary Medicine, Mansoura University, Mansoura, Dakahlia Governorate 35516, Egypt
| | - D D Grosz
- Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States
| | - A J Smart
- Department of Natural Resources, South Dakota State University, Brookings, SD 57007, United States
| | - M B Hildreth
- Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States.
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Drag M, Höglund J, Nejsum P, Thamsborg SM, Enemark HL. The level of embryonation influences detection of Ostertagia ostertagi eggs by semi-quantitative PCR. Parasit Vectors 2016; 9:368. [PMID: 27357701 PMCID: PMC4928311 DOI: 10.1186/s13071-016-1657-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/20/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Internal Transcribed Spacer 2 (ITS2) is a candidate diagnostic marker of the pathogenic cattle nematode Ostertagia ostertagi. The aims of this study were: (i) to document and quantify how the development of O. ostertagi eggs affects ITS2 copies under different storage conditions, and (ii) to suggest optimal storage conditions for faecal samples in a diagnostic pipeline that involves detection and semi-quantification by real-time semi-quantitative polymerase chain reaction (qPCR). FINDINGS Eggs of Ostertagia ostertagi were obtained from fresh faeces and stored at 4 °C or 25 °C under aerobic or anaerobic (vacuum packing) conditions. Development was monitored by microscopy for up to 336 h, and the ITS2 copies were determined by qPCR from a fixed number of parasites. Under aerobic conditions at 25 °C, embryonation and a significant increase of ITS2 copies (P < 0.0001) were observed after 12 h. At 4 °C, embryonation occurred after 168 h with a trend towards increased ITS2 copies. Anaerobic conditions inhibited egg development at both temperatures and no significant increase in ITS2 copies was noticed (P = 0.90). ITS2 copies were analysed for each parasite stage: first-stage larvae (L1) exhibited significantly higher copy numbers (20,353 ± 1,950) than unembryonated eggs (568 ± 168; P < 0.0001) with lower coefficient of variation (33 vs 266 %). CONCLUSIONS Aerobic storage of O. ostertagi eggs at 25 °C led to a significant increase in ITS2 copies after 12 h due to embryonation and subsequent hatching. In contrast, anaerobic storage (vacuum packing) at 25 °C completely inhibited egg development and any undesirable semi-quantification bias for up to 336 h. Hence, vacuum packing is an optimal storage strategy prior to molecular diagnostic analyses. Alternatively, aerobic storage at 4 °C for up to 72 h can be used. Due to high copy numbers and lower genetic variation, the L1 stage may be considered for diagnostics and further molecular research.
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Affiliation(s)
- Markus Drag
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark. .,Section for Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, Frederiksberg C, Denmark.
| | - Johan Höglund
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Peter Nejsum
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Stig M Thamsborg
- Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Heidi L Enemark
- Section for Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, Frederiksberg C, Denmark.,Norwegian Veterinary Institute, PO Box 750 Sentrum, Oslo, N-0106, Norway
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Besier RB, Kahn LP, Sargison ND, Van Wyk JA. Diagnosis, Treatment and Management of Haemonchus contortus in Small Ruminants. ADVANCES IN PARASITOLOGY 2016; 93:181-238. [PMID: 27238006 DOI: 10.1016/bs.apar.2016.02.024] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Haemonchus contortus is a highly pathogenic, blood-feeding nematode of small ruminants, and a significant cause of mortalities worldwide. Haemonchosis is a particularly significant threat in tropical, subtropical and warm temperate regions, where warm and moist conditions favour the free-living stages, but periodic outbreaks occur more widely during periods of transient environmental favourability. The clinical diagnosis of haemonchosis is based mostly on the detection of anaemia in association with a characteristic epidemiological picture, and confirmed at postmortem by the finding of large numbers of H. contortus in the abomasum. The detection of impending haemonchosis relies chiefly on periodic monitoring for anaemia, including through the 'FAMACHA' conjunctival-colour index, or through faecal worm egg counts and other laboratory procedures. A range of anthelmintics for use against H. contortus is available, but in most endemic situations anthelmintic resistance significantly limits the available treatment options. Effective preventative programmes vary depending on environments and enterprise types, and according to the scale of the haemonchosis risk and the local epidemiology of infections, but should aim to prevent disease outbreaks while maintaining anthelmintic efficacy. Appropriate strategies include animal management programmes to avoid excessive H. contortus challenge, genetic and nutritional approaches to enhance resistance and resilience to infection, and the monitoring of H. contortus infection on an individual animal or flock basis. Specific strategies to manage anthelmintic resistance centre on the appropriate use of effective anthelmintics, and refugia-based treatment schedules. Alternative approaches, such as biological control, may also prove useful, and vaccination against H. contortus appears to have significant potential in control programmes.
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Affiliation(s)
- R B Besier
- Department of Agriculture and Food Western Australia, Albany, WA, Australia
| | - L P Kahn
- University of New England, Armidale, NSW, Australia
| | - N D Sargison
- University of Edinburgh, Roslin, Midlothian, United Kingdom
| | - J A Van Wyk
- University of Pretoria, Hatfield, South Africa
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Zarlenga D, Hoberg E, Tuo W. The Identification of Haemonchus Species and Diagnosis of Haemonchosis. ADVANCES IN PARASITOLOGY 2016; 93:145-80. [PMID: 27238005 DOI: 10.1016/bs.apar.2016.02.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Diagnosis is often equated with identification or detection when discussing parasitic diseases. Unfortunately, these are not necessarily mutually exclusive activities; diseases and infections are generally diagnosed and organisms are identified. Diagnosis is commonly predicated upon some clinical signs; in an effort to determine the causative agent, identification of genera and species is subsequently performed. Both identification and diagnosis play critical roles in managing an infection, and involve the interplay of direct and indirect methods of detection, particularly in light of the complex and expanding problem of drug-resistance in parasites. Accurate and authoritative identification that is cost- and time-effective, based on structural and molecular attributes of specimens, provides a foundation for defining parasite diversity and changing patterns of geographical distribution, host association and emergence of disease. Most techniques developed thus far have been grounded in assumptions based on strict host associations between Haemonchus contortus and small ruminants, that is, sheep and goats, and between Haemonchus placei and bovids. Current research and increasing empirical evidence of natural infections in the field demonstrates that this assumption misrepresents the host associations for these species of Haemonchus. Furthermore, the capacity of H. contortus to utilize a considerably broad spectrum of ungulate hosts is reflected in our understanding of the role of anthropogenic forcing, the 'breakdown' of ecological isolation, global introduction and host switching as determinants of distribution. Nuanced insights about distribution, host association and epidemiology have emerged over the past 30years, coincidently with the development of increasingly robust means for parasite identification. In this review and for the sake of argument, we would like to delineate the diagnosis of haemonchosis from the identification of the specific pathogen. As a foundation for exploring host and parasite biology, we will examine the evolution of methods for distinguishing H. contortus from other common gastrointestinal nematodes of agriculturally significant and free-ranging wild ruminants using morphological, molecular and/or immunological methods for studies at the species and genus levels.
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Collender PA, Kirby AE, Addiss DG, Freeman MC, Remais JV. Methods for Quantification of Soil-Transmitted Helminths in Environmental Media: Current Techniques and Recent Advances. Trends Parasitol 2015; 31:625-639. [PMID: 26440788 DOI: 10.1016/j.pt.2015.08.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/12/2015] [Accepted: 08/14/2015] [Indexed: 12/24/2022]
Abstract
Limiting the environmental transmission of soil-transmitted helminths (STHs), which infect 1.5 billion people worldwide, will require sensitive, reliable, and cost-effective methods to detect and quantify STHs in the environment. We review the state-of-the-art of STH quantification in soil, biosolids, water, produce, and vegetation with regard to four major methodological issues: environmental sampling; recovery of STHs from environmental matrices; quantification of recovered STHs; and viability assessment of STH ova. We conclude that methods for sampling and recovering STHs require substantial advances to provide reliable measurements for STH control. Recent innovations in the use of automated image identification and developments in molecular genetic assays offer considerable promise for improving quantification and viability assessment.
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Affiliation(s)
- Philip A Collender
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Amy E Kirby
- Center for Global Safe Water, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | | | - Matthew C Freeman
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
| | - Justin V Remais
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
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Roeber F, Kahn L. The specific diagnosis of gastrointestinal nematode infections in livestock: larval culture technique, its limitations and alternative DNA-based approaches. Vet Parasitol 2014; 205:619-28. [PMID: 25182210 DOI: 10.1016/j.vetpar.2014.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/01/2014] [Accepted: 08/09/2014] [Indexed: 11/29/2022]
Abstract
The specific diagnosis of gastrointestinal nematode infections in ruminants is routinely based on larval culture technique and on the morphological identification of developed third-stage larvae. However, research on the ecology and developmental requirements of different species suggests that environmental conditions (e.g., temperature and humidity) for optimal development to occur vary between the different species. Thus, employing a common culture protocol for all species will favour the development of certain species over others and can cause a biased result in particular when species proportions in a mixed infection are to be determined. Furthermore, the morphological identification of L3 larvae is complicated by a lack of distinctive, obvious features that would allow the identification of all key species. In the present paper we review in detail the potential limitations of larval culture technique and morphological identification and provide account to some modern molecular alternatives to the specific diagnosis of gastrointestinal nematode infection in ruminants.
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Affiliation(s)
- Florian Roeber
- AusDiagnostics Pty. Ltd., Beaconsfield 2015, NSW, Australia.
| | - Lewis Kahn
- Environmental and Rural Science, University of New England, Armidale 2351, NSW, Australia
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22
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Brown DS, Symondson WOC. Sex and age-biased nematode prevalence in reptiles. Mol Ecol 2014; 23:3890-9. [DOI: 10.1111/mec.12688] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 01/30/2014] [Accepted: 01/31/2014] [Indexed: 12/01/2022]
Affiliation(s)
- David S. Brown
- Cardiff School of Biosciences; Cardiff University; The Sir Martin Evans Building, Museum Avenue Cardiff CF10 3AX UK
| | - William O. C. Symondson
- Cardiff School of Biosciences; Cardiff University; The Sir Martin Evans Building, Museum Avenue Cardiff CF10 3AX UK
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McNally J, Callan D, Andronicos N, Bott N, Hunt PW. DNA-based methodology for the quantification of gastrointestinal nematode eggs in sheep faeces. Vet Parasitol 2013; 198:325-35. [DOI: 10.1016/j.vetpar.2013.09.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 07/08/2013] [Accepted: 09/14/2013] [Indexed: 10/26/2022]
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Roeber F, Jex AR, Gasser RB. Advances in the diagnosis of key gastrointestinal nematode infections of livestock, with an emphasis on small ruminants. Biotechnol Adv 2013; 31:1135-52. [PMID: 23376340 PMCID: PMC7126997 DOI: 10.1016/j.biotechadv.2013.01.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 12/19/2022]
Abstract
Parasitic nematodes (roundworms) of livestock have major economic impact globally. In spite of the diseases caused by these nematodes and some advances in the design of new therapeutic agents (anthelmintics) and attempts to develop vaccines against some of them, there has been limited progress in the establishment of practical diagnostic techniques. The specific and sensitive diagnosis of gastrointestinal nematode infections of livestock underpins effective disease control, which is highly relevant now that anthelmintic resistance (AR) is a major problem. Traditional diagnostic techniques have major constraints, in terms of sensitivity and specificity. The purpose of this article is to provide a brief background on gastrointestinal nematodes (Strongylida) of livestock and their control; to summarize conventional methods used for the diagnosis and discuss their constraints; to review key molecular-diagnostic methods and recent progress in the development of advanced amplification-based and sequencing technologies, and their implications for epidemiological investigations and the control of parasitic diseases.
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Affiliation(s)
| | | | - Robin B. Gasser
- Faculty of Veterinary Science, The University of Melbourne, Victoria 3010, Australia
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Grosz D, Eljaki A, Holler L, Petersen D, Holler S, Hildreth M. Overwintering strategies of a population of anthelmintic-resistant Haemonchus contortus within a sheep flock from the United States Northern Great Plains. Vet Parasitol 2013; 196:143-52. [DOI: 10.1016/j.vetpar.2013.01.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 01/27/2013] [Accepted: 01/28/2013] [Indexed: 10/27/2022]
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Demeler J, Ramünke S, Wolken S, Ianiello D, Rinaldi L, Gahutu JB, Cringoli G, von Samson-Himmelstjerna G, Krücken J. Discrimination of gastrointestinal nematode eggs from crude fecal egg preparations by inhibitor-resistant conventional and real-time PCR. PLoS One 2013; 8:e61285. [PMID: 23620739 PMCID: PMC3631180 DOI: 10.1371/journal.pone.0061285] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/08/2013] [Indexed: 11/18/2022] Open
Abstract
Diagnosis of gastrointestinal nematodes relies predominantly on coproscopic methods such as flotation, Kato-Katz, McMaster or FLOTAC. Although FLOTAC allows accurate quantification, many nematode eggs can only be differentiated to genus or family level. Several molecular diagnostic tools discriminating closely related species suffer from high costs for DNA isolation from feces and limited sensitivity since most kits use only small amounts of feces (<1 g). A direct PCR from crude egg preparations was designed for full compatibility with FLOTAC to accurately quantify eggs per gram feces (epg) and determine species composition. Eggs were recovered from the flotation solution and concentrated by sieving. Lysis was achieved by repeated boiling and freezing cycles – only Trichuris eggs required additional mechanic disruption. Egg lysates were directly used as template for PCR with Phusion DNA polymerase which is particularly resistant to PCR inhibitors. Qualitative results were obtained with feces of goats, cattle, horses, swine, cats, dogs and mice. The finally established protocol was also compatible with quantitative real-time PCR in the presence of EvaGreen and no PCR inhibition was detectable when extracts were diluted at least fourfold. Sensitivity was comparable to DNA isolation protocols and spiked samples with five epg were reliably detected. For Toxocara cati a detection limit below one epg was demonstrated. It was possible to distinguish T. cati and Toxocara canis using high resolution melt (HRM) analysis, a rapid tool for species identification. In human samples, restriction fragment length polymorphism (RFLP) and HRM analysis were used to discriminate Necator americanus and Ancylostoma duodenale. The method is able to significantly improve molecular diagnosis of gastrointestinal nematodes by increasing speed and sensitivity while decreasing overall costs. For identification of species or resistance alleles, analysis of PCR products with many different post PCR methods can be used such as RFLP, reverse-line-blot, Sanger sequencing and HRM.
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Affiliation(s)
- Janina Demeler
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Sabrina Ramünke
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Sonja Wolken
- Institute for Parasitology, University for Veterinary Medicine, Hannover, Germany
| | - Davide Ianiello
- Department of Pathology and Animal Health, Faculty of Veterinary Medicine, University of Napels Frederico II, Naples, Italy
| | - Laura Rinaldi
- Department of Pathology and Animal Health, Faculty of Veterinary Medicine, University of Napels Frederico II, Naples, Italy
| | - Jean Bosco Gahutu
- University Teaching Hospital of Butare, Faculty of Medicine, National University of Rwanda, Butare, Rwanda
| | - Giuseppe Cringoli
- Department of Pathology and Animal Health, Faculty of Veterinary Medicine, University of Napels Frederico II, Naples, Italy
| | | | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail:
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Developmental stage of strongyle eggs affects the outcome variations of real-time PCR analysis. Vet Parasitol 2013; 191:191-6. [DOI: 10.1016/j.vetpar.2012.08.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 08/23/2012] [Indexed: 11/23/2022]
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28
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Roeber F, Jex AR, Gasser RB. Next-generation molecular-diagnostic tools for gastrointestinal nematodes of livestock, with an emphasis on small ruminants: a turning point? ADVANCES IN PARASITOLOGY 2013; 83:267-333. [PMID: 23876874 PMCID: PMC7150098 DOI: 10.1016/b978-0-12-407705-8.00004-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Parasitic nematodes of livestock have major economic impact worldwide. Despite the diseases caused by these nematodes, some advances towards the development of new therapeutic agents and attempts to develop effective vaccines against some of them, there has been limited progress in the development of practical diagnostic methods. The specific and sensitive diagnosis of parasitic nematode infections of livestock underpins effective disease control, which is now particularly important given the problems associated with anthelmintic resistance in parasite populations. Traditional diagnostic methods have major limitations, in terms of sensitivity and specificity. This chapter provides an account of the significance of parasitic nematodes (order Strongylida), reviews conventional diagnostic techniques that are presently used routinely and describes advances in polymerase chain reaction (PCR)-based methods for the specific diagnosis of nematode infections. A particular emphasis is placed on the recent development of a robotic PCR-based platform for high-throughput diagnosis, and its significance and implications for epidemiological investigations and for use in control programmes.
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Affiliation(s)
| | | | - Robin B. Gasser
- Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia
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29
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Demeler J, Schein E, von Samson-Himmelstjerna G. Advances in laboratory diagnosis of parasitic infections of sheep. Vet Parasitol 2012; 189:52-64. [DOI: 10.1016/j.vetpar.2012.03.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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30
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Which McMaster egg counting technique is the most reliable? Parasitol Res 2011; 109:1387-94. [DOI: 10.1007/s00436-011-2385-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 04/06/2011] [Indexed: 11/30/2022]
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31
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Schriewer A, Wehlmann A, Wuertz S. Improving qPCR efficiency in environmental samples by selective removal of humic acids with DAX-8. J Microbiol Methods 2011; 85:16-21. [DOI: 10.1016/j.mimet.2010.12.027] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 11/15/2022]
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32
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Fang W, Liu F, Zhang S, Lin J, Xu S, Luo D. Anisakis pegreffii: a quantitative fluorescence PCR assay for detection in situ. Exp Parasitol 2010; 127:587-92. [PMID: 21110972 DOI: 10.1016/j.exppara.2010.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 11/13/2010] [Accepted: 11/17/2010] [Indexed: 10/18/2022]
Abstract
To facilitate improved diagnosis and detection of the third stage larva (L3) of Anisakis pegreffii from the Minnan-Taiwan bank fishing ground in Taiwan Strait, a real-time PCR method for the detection in situ and differentiation was developed to amplify a region of the second internal transcribed spacer (ITS-2) of this parasite. The real-time PCR assay was capable of detecting 1/3 of a single L3 in 30 mg of marine fish tissue, and also exhibited a high level of specificity for A. pegreffii, no fluorescence signals were observed in other five major larval anisakid species found in commercial marine fishes caught in this fishing ground.
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Affiliation(s)
- Wenzhen Fang
- School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China
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33
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Dangoudoubiyam S, Vemulapalli R, Kazacos KR. PCR assays for detection of Baylisascaris procyonis eggs and larvae. J Parasitol 2010; 95:571-7. [PMID: 19090651 DOI: 10.1645/ge-1905.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 12/11/2008] [Indexed: 11/10/2022] Open
Abstract
The objective of this study was to develop polymerase chain reaction (PCR) assays for detection of Baylisascaris procyonis eggs and larvae in fecal, environmental, and tissue samples. We have optimized conventional and real-time PCR assays for B. procyonis using the mitochondrial cytochrome oxidase 2 gene as the target for amplification. The lower limit of detection of the parasite genomic DNA was 10 pg in the conventional PCR and 100 fg in the real-time PCR. In both PCR assays, specific amplification of a 146 bp product was achieved with DNA extracted from a single in vitro hatched B. procyonis larva and also from canine fecal samples spiked with as few as 20 unembryonated B. procyonis eggs per gram of feces. The PCR assays were successfully used for detection of B. procyonis eggs and larvae in fecal, environmental, and tissue samples. No DNA amplification was seen when the genomic DNA of related ascarids (including B. transfuga) and a hookworm was used as template in the PCR; however, amplification was seen with the very closely related B. columnaris.
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Affiliation(s)
- Sriveny Dangoudoubiyam
- Department of Comparative Pathobiology, Purdue University, West Lafayette, Indiana 47907, USA.
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34
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Learmount J, Conyers C, Hird H, Morgan C, Craig BH, von Samson-Himmelstjerna G, Taylor M. Development and validation of real-time PCR methods for diagnosis of Teladorsagia circumcincta and Haemonchus contortus in sheep. Vet Parasitol 2009; 166:268-74. [PMID: 19836895 DOI: 10.1016/j.vetpar.2009.08.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/06/2009] [Accepted: 08/18/2009] [Indexed: 10/20/2022]
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35
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Bott NJ, Campbell BE, Beveridge I, Chilton NB, Rees D, Hunt PW, Gasser RB. A combined microscopic-molecular method for the diagnosis of strongylid infections in sheep. Int J Parasitol 2009; 39:1277-87. [PMID: 19328802 DOI: 10.1016/j.ijpara.2009.03.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 03/16/2009] [Accepted: 03/18/2009] [Indexed: 11/29/2022]
Abstract
We evaluated a combined microscopic-molecular approach for the diagnosis of key strongylid infections in sheep using panels of well-defined control and test samples. The method established is based on the separation of nematode eggs from faecal samples using a salt flotation procedure, the extraction and column-purification of genomic DNA, followed by real-time PCR and melting-curve analysis. Specific and semi-quantitative amplification from (a minimum of 0.1-2.0pg) genomic DNA of Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp., Cooperia oncophora, Oesophagostomum columbianum, Oesophagostomum venulosum or Chabertia ovina is achieved using a specific, forward oligonucleotide primer located in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) together with a conserved reverse primer in the large subunit of rDNA. Using a panel of well-defined genomic DNA samples from eggs from sheep monospecifically infected with H. contortus or Te. circumcincta, there was a correlation between cycle threshold (Ct) values in the PCR and numbers of egg per gram of faeces, thus allowing the semi-quantitation of parasite DNA in faeces. The findings of the present study indicate that a microscopic-molecular approach provides a useful tool for diagnosis, for epidemiological and ecological surveys as well as for integration into parasite monitoring, drug resistance (i.e. 'egg count reduction') testing or control programmes, particularly following semi- or full-automation.
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Affiliation(s)
- Nathan J Bott
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Vic. 3030, Australia
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36
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Toward practical, DNA-based diagnostic methods for parasitic nematodes of livestock — Bionomic and biotechnological implications. Biotechnol Adv 2008; 26:325-34. [DOI: 10.1016/j.biotechadv.2008.03.003] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/06/2008] [Accepted: 03/14/2008] [Indexed: 11/22/2022]
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37
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Nielsen MK, Peterson DS, Monrad J, Thamsborg SM, Olsen SN, Kaplan RM. Detection and semi-quantification of Strongylus vulgaris DNA in equine faeces by real-time quantitative PCR. Int J Parasitol 2008; 38:443-53. [PMID: 17889881 DOI: 10.1016/j.ijpara.2007.07.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 07/22/2007] [Accepted: 07/27/2007] [Indexed: 10/23/2022]
Abstract
Strongylus vulgaris is an important strongyle nematode with high pathogenic potential infecting horses world-wide. Several decades of intensive anthelmintic use has virtually eliminated clinical disease caused by S. vulgaris, but has also caused high levels of anthelmintic resistance in equine small strongyle (cyathostomin) nematodes. Recommendations aimed at limiting the development of anthelmintic resistance by reducing treatment intensity raises a simultaneous demand for reliable and accurate diagnostic tools for detecting important parasitic pathogens. Presently, the only means available to differentiate among strongyle species in a faecal sample is by identifying individual L3 larvae following a two week coproculture procedure. The aim of the present study is to overcome this diagnostic obstacle by developing a fluorescence-based quantitative PCR assay capable of identifying S. vulgaris eggs in faecal samples from horses. Species-specific primers and a TaqMan probe were designed by alignment of published ribosomal DNA sequences of the second internal transcribed spacer of cyathostomin and Strongylus spp. nematodes. The assay was tested for specificity and optimized using genomic DNA extracted from identified male worms of Strongylus and cyathostomin species. In addition, eggs were collected from adult female worms and used to evaluate the quantitative potential of the assay. Statistically significant linear relationships were found between egg numbers and cycle of threshold (Ct) values. PCR results were unaffected by the presence of cyathostomin DNA in the sample and there was no indication of PCR inhibition by faecal sources. A field evaluation on faecal samples obtained from four Danish horse farms revealed a good agreement with the traditional larval culture (kappa-value=0.78), but with a significantly higher performance of the PCR assay. An association between Ct values and S. vulgaris larval counts was statistically significant. The present assay can reliably and semi-quantitatively detect minute quantities of S. vulgaris eggs in faecal samples.
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Affiliation(s)
- Martin K Nielsen
- Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Denmark.
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