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Smit A, Mulandane FC, Wojcik SH, Horak IG, Makepeace BL, Morar-Leather D, Neves L. Sympatry of Amblyomma eburneum and Amblyomma variegatum on African buffaloes and prevalence of pathogens in ticks. Ticks Tick Borne Dis 2023; 14:102247. [PMID: 37651847 DOI: 10.1016/j.ttbdis.2023.102247] [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: 05/16/2023] [Revised: 07/20/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023]
Abstract
The Amblyomma genus is represented on the African continent by 24 species, out of which 17 are known to occur in different ecological niches of southern Africa. Amblyomma, known for their aggressive hunting behaviour and aptitude as pathogen vectors, are of main concern to travellers, mainly in rural and conservation areas of Africa. In this study, we highlight the overlapping distribution of Amblyomma eburneum and Amblyomma variegatum found on African buffaloes (Syncerus caffer) at Coutada 11, Central Mozambique. In total, 1,039 Amblyomma ticks were collected and morphologically identified using taxonomic keys, and genomic DNA was extracted. They were subjected to reverse line blotting for pathogen identification followed by molecular analysis (COI sequencing) of both tick species. Pathogens such as Ehrlichia ruminantium, Anaplasma centrale, Theileria sp., Babesia sp. and Rickettsia africae were detected, of which R. africae is zoonotic. Ehrlichia ruminantium, R. africae, Theileria mutans and Theileria velifera are well-established pathogens transmitted by Amblyomma ticks; however, Anaplasma spp. and Babesia spp. are not, suggesting residual parasite DNA in the bloodmeal. Little is mentioned in the literature about A. eburneum, including its role as a vector and reservoir for pathogens. In Mozambique A. eburneum is currently restricted to wildlife but the spread of the tick may be observed given the climate change that is occurring. The infection rates for the pathogens in both Amblyomma tick species were lower than expected, but this may be due to the low host density in the forest niche and the innate immunity of these hosts. With the propensity of ticks of the Amblyomma genus to form parapatric distributions, the mechanisms that allows for the overlapping distribution of these two Amblyomma species while maintaining tick species identity is of great interest.
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Affiliation(s)
- Andeliza Smit
- Tick Research Group, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, 0110, South Africa.
| | - Fernando C Mulandane
- Biotechnology Center, Eduardo Mondlane University, Av. Moçambique Km 1.5, Maputo, Mozambique
| | - Stephané H Wojcik
- Tick Research Group, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Ivan G Horak
- Tick Research Group, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom
| | - Darshana Morar-Leather
- Tick Research Group, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Luis Neves
- Tick Research Group, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, 0110, South Africa; Biotechnology Center, Eduardo Mondlane University, Av. Moçambique Km 1.5, Maputo, Mozambique
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Omondi D, Zweygarth E, Murungi E, Jongejan F, Nijhof AM. De novo assembly and annotation of the Amblyomma hebraeum tick midgut transcriptome response to Ehrlichia ruminantium infection. PLoS Negl Trop Dis 2023; 17:e0011554. [PMID: 37578991 PMCID: PMC10449191 DOI: 10.1371/journal.pntd.0011554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 08/24/2023] [Accepted: 07/26/2023] [Indexed: 08/16/2023] Open
Abstract
The South African bont tick Amblyomma hebraeum is a hematophagous vector for the heartwater disease pathogen Ehrlichia ruminantium in southern Africa. During feeding, the tick's enterocytes express proteins that perform vital functions in blood digestion, including proteins that may be involved in E. ruminantium acquisition, colonization or immunity. To delineate the molecular mechanism of midgut response to E. ruminantium infection, we performed comparative analyses of midgut transcriptomes of E. ruminantium infected engorged A. hebraeum nymphs, and infected adult male and female ticks with their corresponding matched uninfected controls, before and during feeding. A total of 102,036 unigenes were annotated in public databases and their expression levels analyzed for engorged nymphs as well as unfed and partly-fed adult ticks. There were 2,025 differentially expressed genes (DEGs) in midguts, of which 1,225 unigenes were up-regulated and 800 unigenes were down-regulated in the midguts of infected ticks. Annotation of DEGs revealed an increase in metabolic and cellular processes among E. ruminantium infected ticks. Notably, among the infected ticks, there was up-regulation in the expression of genes involved in tick immunity, histone proteins and oxidative stress responses. We also observed up-regulation of glycoproteins that E. ruminantium could potentially use as docking sites for host cell entry. Insights uncovered in this study offer a platform for further investigations into the molecular interaction between E. ruminantium and A. hebraeum.
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Affiliation(s)
- David Omondi
- Institute of Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, Berlin, Germany
- Department of Biochemistry and Molecular Biology, Egerton University, Njoro, Kenya
| | - Erich Zweygarth
- Institute of Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Edwin Murungi
- Department of Medical Biochemistry, School of Health Sciences, Kisii University, Kisii, Kenya
| | - Frans Jongejan
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Ard M. Nijhof
- Institute of Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, Berlin, Germany
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Ngnindji-Youdje Y, Diarra AZ, Lontsi-Demano M, Tchuinkam T, Parola P. Detection of Tick-Borne Pathogens in Ticks from Cattle in Western Highlands of Cameroon. Microorganisms 2022; 10:microorganisms10101957. [PMID: 36296233 PMCID: PMC9609823 DOI: 10.3390/microorganisms10101957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/22/2022] [Accepted: 09/27/2022] [Indexed: 11/15/2022] Open
Abstract
This study aimed to detect and identify microorganisms in ticks collected in the Western Highlands of Cameroon. Quantitative real-time and standard PCR assays, coupled with sequencing, were used. A total of 944 ticks collected from cattle in five distinct sites in Cameroon were selected for the analyses. They belonged to five genera (Amblyomma, Hyalomma, Rhipicephalus, Haemaphysalis, and Ixodes) and twelve species. Real-time PCR revealed that 23% (n = 218) of the ticks were positive for Rickettsia spp., 15% (n = 141) for bacteria of the Anaplasmataceae family, 3% (n = 29) for Piroplasmida, 0.5% (n = 5) for Coxiella burnetii, 0.4% (n = 4) for Borrelia spp., and 0.2% (n = 2) for Bartonella spp. The co-infection rate (3.4%, n = 32) involved mainly Rickettsia spp. and Anaplasmataceae. Of the Rickettsia spp. positive ticks, the targeted PCR and sequencing yielded Rickettsia africae (78.9%), Rickettsia aeschlimannii (6.4%), Rickettsia massiliae (7.8%), Candidatus Rickettsia barbariae (0.9%), and Rickettsia sp. (0.9%). Anaplasmataceae included Anaplasma marginale (4.3%), Anaplasma platys (1.4%), Anaplasma centrale (0.7%), Ehrlichia ruminantium (0.7%), Wolbachia sp., Candidatus Ehrlichia rustica (13.5%), Candidatus Ehrlichia urmitei (7%), and an uncultured Ehrlichia sp. (4.2%). Borrelia theileri was identified in one Rhipicephalus microplus tick. Unfortunately, Piroplasmida could not be identified to the species level. This study demonstrates that in Cameroon, ticks harbour a wide variety of microorganisms and present a risk of zoonotic diseases.
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Affiliation(s)
- Yannick Ngnindji-Youdje
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France
- IHU-Méditerranée Infection, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon
| | - Adama Zan Diarra
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France
- IHU-Méditerranée Infection, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
| | - Michel Lontsi-Demano
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon
| | - Timoléon Tchuinkam
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon
| | - Philippe Parola
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France
- IHU-Méditerranée Infection, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Correspondence: ; Tel.: +33-(0)-4-13-73-24-01; Fax: +33-(0)-4-13-73-24-02
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Mnisi SS, Mphuthi MBN, Ramatla T, Mofokeng LS, Thekisoe O, Syakalima M. Molecular Detection and Genetic Characterization of Ehrlichia ruminantium Harbored by Amblyomma hebraeum Ticks of Domestic Ruminants in North West Province, South Africa. Animals (Basel) 2022; 12:ani12192511. [PMID: 36230251 PMCID: PMC9559644 DOI: 10.3390/ani12192511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/12/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022] Open
Abstract
Ehrlichia ruminantium (E. ruminantium) is the causative agent of heartwater disease and it is mainly transmitted to livestock by Amblyomma hebraeum (A. hebraeum) tick in South Africa. This study investigated the occurrence of E. ruminantium and its genetic diversity in ticks within Ngaka Modiri Molema district of North West Province in South Africa. Genomic DNA was extracted from whole A. hebraeum ticks totaling 876 and resulted in a total of 292 pooled DNA samples. Firstly, conventional PCR was used to detect Ehrlichia spp. targeting the dsbA gene, followed by nested PCR targeting the Map1 gene performed on DNA pool samples that were positive from the first PCR. One hundred and six tick DNA pool samples were positive by dsbA gene PCR for the presence of Ehrlichia spp. with minimum infection rate (MIR) of 121, while 13/106 were positive by Map1 PCR with MIR of 15. Different E. ruminantium Map1 genotypes (NWUe1, NWUe2, NWUe3, NWUe5, and NWUe6) were detected from tick samples and were closely related to more than 13 gene sequences of E. ruminantium from the NCBI GenBank database. These findings suggest that there is a significant diversity of E. ruminantium infecting ticks in the study area.
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Affiliation(s)
- Sifiso S. Mnisi
- Department of Animal Health, School of Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
| | - Malekoba B. N. Mphuthi
- Department of Animal Health, School of Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
| | - Tsepo Ramatla
- Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2531, South Africa
- Correspondence: ; Tel.: +27-18-299-2521
| | - Lehlohonolo S. Mofokeng
- Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2531, South Africa
| | - Oriel Thekisoe
- Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2531, South Africa
| | - Michelo Syakalima
- Department of Animal Health, School of Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
- Disease Control Department, School of Veterinary Medicine, University of Zambia, Lusaka P.O. Box 32379, Zambia
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Mendoza-Roldan JA, Mendoza-Roldan MA, Otranto D. Reptile vector-borne diseases of zoonotic concern. Int J Parasitol Parasites Wildl 2021; 15:132-142. [PMID: 34026483 PMCID: PMC8121771 DOI: 10.1016/j.ijppaw.2021.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022]
Abstract
Reptile vector-borne diseases (RVBDs) of zoonotic concern are caused by bacteria, protozoa and viruses transmitted by arthropod vectors, which belong to the subclass Acarina (mites and ticks) and the order Diptera (mosquitoes, sand flies and tsetse flies). The phyletic age of reptiles since their origin in the late Carboniferous, has favored vectors and pathogens to co-evolve through millions of years, bridging to the present host-vector-pathogen interactions. The origin of vector-borne diseases is dated to the early cretaceous with Trypanosomatidae species in extinct sand flies, ancestral of modern protozoan hemoparasites of zoonotic concern (e.g., Leishmania and Trypanosoma) associated to reptiles. Bacterial RVBDs are represented by microorganisms also affecting mammals of the genera Aeromonas, Anaplasma, Borrelia, Coxiella, Ehrlichia and Rickettsia, most of them having reptilian clades. Finally, reptiles may play an important role as reservoirs of arborivuses, given the low host specificity of anthropophilic mosquitoes and sand flies. In this review, vector-borne pathogens of zoonotic concern from reptiles are discussed, as well as the interactions between reptiles, arthropod vectors and the zoonotic pathogens they may transmit.
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Affiliation(s)
| | | | - Domenico Otranto
- Department of Veterinary Medicine, University of Bari, Valenzano, Italy
- Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamedan, Iran
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Noroy C, Meyer DF. The super repertoire of type IV effectors in the pangenome of Ehrlichia spp. provides insights into host-specificity and pathogenesis. PLoS Comput Biol 2021; 17:e1008788. [PMID: 34252087 PMCID: PMC8274917 DOI: 10.1371/journal.pcbi.1008788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/26/2021] [Indexed: 11/28/2022] Open
Abstract
The identification of bacterial effectors is essential to understand how obligatory intracellular bacteria such as Ehrlichia spp. manipulate the host cell for survival and replication. Infection of mammals–including humans–by the intracellular pathogenic bacteria Ehrlichia spp. depends largely on the injection of virulence proteins that hijack host cell processes. Several hypothetical virulence proteins have been identified in Ehrlichia spp., but one so far has been experimentally shown to translocate into host cells via the type IV secretion system. However, the current challenge is to identify most of the type IV effectors (T4Es) to fully understand their role in Ehrlichia spp. virulence and host adaptation. Here, we predict the T4E repertoires of four sequenced Ehrlichia spp. and four other Anaplasmataceae as comparative models (pathogenic Anaplasma spp. and Wolbachia endosymbiont) using previously developed S4TE 2.0 software. This analysis identified 579 predicted T4Es (228 pT4Es for Ehrlichia spp. only). The effector repertoires of Ehrlichia spp. overlapped, thereby defining a conserved core effectome of 92 predicted effectors shared by all strains. In addition, 69 species-specific T4Es were predicted with non-canonical GC% mostly in gene sparse regions of the genomes and we observed a bias in pT4Es according to host-specificity. We also identified new protein domain combinations, suggesting novel effector functions. This work presenting the predicted effector collection of Ehrlichia spp. can serve as a guide for future functional characterisation of effectors and design of alternative control strategies against these bacteria. A fundamental step for the survival and replication of intravacuolar bacterial pathogens is the establishment of a replicative niche inside host cells by the secretion of bacterial effector proteins in the cytoplasm of the infected cells. These effectors manipulate host signaling pathways, thus allowing to escape the host degradative pathway and uptake nutrients required for intracellular replication of bacteria. In this study, we used S4TE2.0 software for high-throughput computational prediction of bacterial type IV effectors in zoonotic bacteria of the Anaplasmataceae family. The analysis of protein architecture of effectors helped us to identify the cellular pathways targeted during the infection process. The demonstration that effectors are modular components with a broad variety of protein architectures nicely explains their pleotropic mode of action and enlightens their function. We showed that bacterial adaptation to a given host during evolution requires a minimal repertoire of candidate effectors although further experimental determination is needed. T4Es are of increasing interest for basic research, including comprehension of hijacked cellular pathways, manipulated innate immunity, and application for therapeutics. Indeed pathogenomics-driven studies, especially on genetically intractable intracellular bacteria such as Anaplasmataceae, have now a substantial impact for the development of host-targeted antimicrobials, as an alternative to antibiotics.
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Affiliation(s)
- Christophe Noroy
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRA, Univ Montpellier, Montpellier, France
- Université des Antilles, Fouillole, Pointe-à-Pitre, Guadeloupe, France
| | - Damien F. Meyer
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRA, Univ Montpellier, Montpellier, France
- * E-mail:
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Mora-Rivera C, Suarez-Páez F, Pacheco-Sierra G, Vargas-Cuevas L, Padilla-Barreto M. Tick Infection of Caiman crocodilus fuscus at the Hidroprado Hydroelectric Dam in Colombia: New Records, Parasite Prevalence, and Blood Loss Rate. SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2020. [DOI: 10.2994/sajh-d-18-00080.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Cristina Mora-Rivera
- Grupo de Investigación en Biodiversidad y Dinámica de Ecosistemas Tropicales, Universidad de Tolima, Ibagué 730006299, Colombia
| | - Fernando Suarez-Páez
- Semillero de Investigación en Fauna Silvestre, Facultad de Medicina Veterinaria y Zootecnia, Universidad Cooperativa de Colombia sede Ibagué-Espinal, Ibagué, Colombia
| | - Gualberto Pacheco-Sierra
- Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción, Matteri y España E3105BWA, Diamante, Argentina
| | - Laura Vargas-Cuevas
- Semillero de Investigación en Fauna Silvestre, Facultad de Medicina Veterinaria y Zootecnia, Universidad Cooperativa de Colombia sede Ibagué-Espinal, Ibagué, Colombia
| | - Mónica Padilla-Barreto
- Grupode Investigación Impronta, Facultad de Medicina Veterinaria y Zootecnia, Universidad Cooperativa de Colombia sede Ibagué-Espinal, Ibagué, Tolima, Colombia
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Abstract
Emerging infectious diseases (EIDs) are a growing global health threat. The Stockholm Paradigm suggests that their toll will grow tragically in the face of climate change, in particular. The best research protocol for predicting and preventing infectious disease emergence states that an urgent search must commence to identify unknown human and animal pathogens. This short communication proposes that the ethnobiological knowledge of indigenous and impoverished communities can be a source of information about some of those unknown pathogens. I present the ecological and anthropological theory behind this proposal, followed by a few case studies that serve as a limited proof of concept. This paper also serves as a call to action for the medical anthropology community. It gives a brief primer on the EID crisis and how anthropology research may be vital to limiting its havoc on global health. Local knowledge is not likely to play a major role in EID research initiatives, but the incorporation of an awareness of EIDs into standard medical anthropological practice would have myriad other benefits.
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Affiliation(s)
- Hampton Gray Gaddy
- Institute of Human Sciences, University of Oxford, 58a Banbury Rd, Oxford, OX2 6QS, United Kingdom.
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Clift SJ, Collins NE, Oosthuizen MC, Steyl JCA, Lawrence JA, Mitchell EP. The Pathology of Pathogenic Theileriosis in African Wild Artiodactyls. Vet Pathol 2019; 57:24-48. [PMID: 31854265 DOI: 10.1177/0300985819879443] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The published literature on schizont-"transforming," or pathogenic theileriosis, in African wild artiodactyls is dated and based on limited information. Here the authors review the taxonomy, diagnosis, epidemiology, hematology, pathology, and aspects of control in various species. Molecular studies based on 18S and 16S rRNA gene sequences have shown that African wild artiodactyls are commonly infected with diverse Theileria spp., as well as nontheilerial hemoprotozoa and rickettsia-like bacteria, and coinfections with pathogenic and nonpathogenic Theileria species are often recorded. Although theileriosis is still confusingly referred to as cytauxzoonosis in many species, the validity of a separate Cytauxzoon genus in artiodactyls is debated. The epidemiology of theileriosis is complex; the likelihood of fatal disease depends on the interplay of parasite, vertebrate host, tick vector, and environmental factors. Roan calves (Hippotragus equinus) and stressed animals of all host species are more susceptible to fatal theileriosis. Even though regenerative anemia is common, peripheral blood piroplasm parasitemia does not correlate with disease severity. Other than anemia, common macroscopic lesions include icterus, hemorrhages (mucosal, serosal, and tissue), fluid effusions into body cavities, lung edema, and variably sized raised cream-colored foci of leukocyte infiltration in multiple organs. Histopathologic findings include vasocentric hyperproliferation and lysis of atypical leukocytes with associated intracellular schizonts, parenchymal necrosis, hemorrhage, thromboembolism, and edema. Immunophenotyping is required to establish the identity of the schizont-transformed leukocytes in wild ungulates. Throughout the review, we propose avenues for future research by comparing existing knowledge on selected aspects of theileriosis in domestic livestock with that in African wild artiodactyls.
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Affiliation(s)
- Sarah J Clift
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Nicola E Collins
- Vectors and Vector-Borne Diseases Research Program, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Marinda C Oosthuizen
- Vectors and Vector-Borne Diseases Research Program, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Johan C A Steyl
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - John A Lawrence
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Emily P Mitchell
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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Peter SG, Gakuya DW, Maingi N, Mulei CM. Prevalence and risk factors associated with Ehrlichia infections in smallholder dairy cattle in Nairobi City County, Kenya. Vet World 2019; 12:1599-1607. [PMID: 31849422 PMCID: PMC6868257 DOI: 10.14202/vetworld.2019.1599-1607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 09/03/2019] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND AND AIM Ehrlichiosis caused by Ehrlichia ruminantium is a tick-borne disease of great economic importance in cattle production worldwide. Despite its economic impact, limited knowledge is available on its epidemiology in Africa, including Kenya. Suspected cases of E. ruminantium infections have been reported in the recent past to the University of Nairobi's Veterinary Hospital, prompting the need to investigate their possible re-emergence. Therefore, this study was aimed at determining the prevalence of E. ruminantium among smallholder dairy cattle in Nairobi City County and to assess potential risk factors. This knowledge may guide the development of appropriate control strategies of ehrlichiosis, subsequently reducing associated losses. MATERIALS AND METHODS A total of 107 smallholder dairy farms from Nairobi City County were recruited for the study. Blood samples were collected from 314 apparently healthy dairy cattle, and Giemsa-stained blood smears were screened under the microscope for Ehrlichia species. A commercial antigen enzyme-linked immunosorbent assay (ELISA) kit was then used to confirm the presence of the infections in serum samples. A pre-tested questionnaire was used to collect data on management practices that may be potential risk factors. A univariate and mixed-effects logistic regression was then used to determine significant risk factors. RESULTS On microscopy, 79.3% (249/314) of the sampled animals had Ehrlichia-like inclusion bodies in white blood cells, though only 18.6% (95% confidence interval [CI] 14.2-23.0) of these were confirmed to be E. ruminantium on ELISA. A farm-level prevalence of 35.5% (95% CI 27.0-45.3) was reported. Female-headed households (p=0.013), farms in Langata region (p=0.027), cleaning of cowsheds fortnightly (p=0.019), and roofing of cowshed (p=0.022) were factors significantly associated with E. ruminantium infections. CONCLUSION There is a relatively high prevalence of E. ruminantium infections in apparently healthy cattle in smallholder dairy farms in this area, warranting control measures. It is critical to improve animal welfare-related factors, such as cowshed cleaning and roofing, as well as the strategic location of farms, especially, since reservoirs may reduce infection levels in the farms, in relation to wildlife. However, since Ehrlichia-like inclusion bodies other than those of E. ruminantium were observed in this study, there is a need to investigate further these factors and the possibility of other Ehrlichia species infecting cattle in the study area.
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Affiliation(s)
- Shepelo Getrude Peter
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Kenya
| | - Daniel Waweru Gakuya
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Kenya
| | - Ndichu Maingi
- Department of Veterinary Pathology, Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Nairobi, Kenya
| | - Charles Matiku Mulei
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Kenya
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El-Neweshy MS, Al Mawly JH, Aboollo SH, El-Manakhly EM. Natural Ehrlichia ruminantium infection in two captive Arabian tahrs (Arabitragus jayakari) in Oman. Trop Anim Health Prod 2019; 51:2539-2545. [PMID: 31214965 DOI: 10.1007/s11250-019-01970-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 06/06/2019] [Indexed: 11/28/2022]
Abstract
This study was investigated the cause of death of two captive adult Arabian tahrs (Arabitragus jayakari) died within 2-3 days after onset of fever and neurologic signs in a private farm in northern Batinah Region of Oman. Blood counting revealed leukocytosis attributed to neutrophilia and serum chemistry showed hypoproteinemia, increased creatine kinase and BUN. Upon autopsy, the animals exhibited mild ascites and hydrothorax, prominent hydropericardium, with large pale-yellow clear fluid coagulum, prominent epicardial petechiation, as well as severe pulmonary edema associated with frothy fluid in airways. Brain edema with congestion of meningeal and parenchymal vessels was prominent. Histopathology revealed severe congestion and edema of both lung and brain as well as cardiac myopathy. Ehrlichia ruminantium colonies (the causative organism of cowdriosis; OIE-listed disease) were demonstrated in the capillary endothelium of fresh brain squash and lung macrophages. This is the first report of natural E. ruminantium infection in Arabian tahr, the highly endangered species, based on typical clinical signs of acute cowdriosis and demonstration of E. ruminantium colonies in the brain capillary endothelial cells.
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Affiliation(s)
- Mahmoud S El-Neweshy
- Department of Pathology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt. .,Central Laboratory for Animal Health, Ministry of Agriculture and Fisheries, Muscat, Sultanate of Oman.
| | - Julanda H Al Mawly
- Central Laboratory for Animal Health, Ministry of Agriculture and Fisheries, Muscat, Sultanate of Oman
| | - Safaa H Aboollo
- Pathology Unit, Damnhour Provincial Lab., Animal Health Research Institute, Giza, Egypt
| | - E M El-Manakhly
- Department of Pathology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt.,Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia
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Machado RZ, Teixeira MMG, Rodrigues AC, André MR, Gonçalves LR, Barbosa da Silva J, Pereira CL. Molecular diagnosis and genetic diversity of tick-borne Anaplasmataceae agents infecting the African buffalo Syncerus caffer from Marromeu Reserve in Mozambique. Parasit Vectors 2016; 9:454. [PMID: 27531003 PMCID: PMC4987998 DOI: 10.1186/s13071-016-1715-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/19/2015] [Indexed: 01/08/2023] Open
Abstract
Background Tick-borne diseases (TBDs) are very important in relation to domestic ruminants, but their occurrence among wild ruminants, mainly in the African buffalo Syncerus caffer, remains little known. Methods Molecular diagnostic methods were applied to detect Anaplasma marginale, Anaplasma centrale, Anaplasma phagocytophilum, Ehrlichia ruminantium and Ehrlichia chaffeensis in 97 blood samples of African buffalo captured at the Marromeu Reserve in Mozambique. Molecular detection of agents belonging to the family Anaplasmataceae were based on conventional and qPCR assays based on msp5, groEL, 16S rRNA, msp2, pCS20 and vlpt genes. Phylogenetic reconstruction of new Anaplasma isolates detected in African buffalo was evaluated based on msp5, groEL and 16S rRNA genes. Results All the animals evaluated were negative for specific PCR assays for A. phagocytophilum, E. ruminantium and E. chaffeensis, but 70 animals were positive for A. marginale, showing 2.69 × 100 up to 2.00 × 105msp1β copies/μl. This result overcomes the conventional PCR for A. marginale based on msp5 gene that detected only 65 positive samples. Sequencing and phylogenetic analyses were performed for selected positive samples based on the genes msp5, groEL and 16S rRNA. Trees inferred using different methods separated the 29 msp5 sequences from buffalo in two distinct groups, assigned to A. centrale and A. marginale. The groEL sequences determined for African buffalo samples revealed to be more heterogeneous and inferred trees could not assign them to any species of Anaplasma despite being more related to A. marginale and A. centrale. The highly conserved 16S rRNA gene sequences suggested a close relationship of the new 16 sequences with A. centrale/A. marginale, A. platys and A. phagocytophilum. Conclusions Our analysis suggests that different species of Anaplasma are simultaneously present in the African buffalo. To the best of our knowledge, this is the first study that diagnosed Anaplasma spp. in the African buffalo and inferred the taxonomic status of new isolates with different gene sequences. The small fragment of msp5 sequences revealed to be a good target for phylogenetic positioning of new Anaplasma spp. isolates.
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Affiliation(s)
- Rosangela Zacarias Machado
- Department of Veterinary Pathology, School of Agrarian and Veterinary Sciences (FCAV/UNESP), Jaboticabal, SP, Brazil.
| | | | | | - Marcos Rogério André
- Department of Veterinary Pathology, School of Agrarian and Veterinary Sciences (FCAV/UNESP), Jaboticabal, SP, Brazil
| | - Luiz Ricardo Gonçalves
- Department of Veterinary Pathology, School of Agrarian and Veterinary Sciences (FCAV/UNESP), Jaboticabal, SP, Brazil
| | - Jenevaldo Barbosa da Silva
- Department of Veterinary Pathology, School of Agrarian and Veterinary Sciences (FCAV/UNESP), Jaboticabal, SP, Brazil
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Moumène A, Marcelino I, Ventosa M, Gros O, Lefrançois T, Vachiéry N, Meyer DF, Coelho AV. Proteomic profiling of the outer membrane fraction of the obligate intracellular bacterial pathogen Ehrlichia ruminantium. PLoS One 2015; 10:e0116758. [PMID: 25710494 PMCID: PMC4339577 DOI: 10.1371/journal.pone.0116758] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 12/13/2014] [Indexed: 01/27/2023] Open
Abstract
The outer membrane proteins (OMPs) of Gram-negative bacteria play a crucial role in virulence and pathogenesis. Identification of these proteins represents an important goal for bacterial proteomics, because it aids in vaccine development. Here, we have developed such an approach for Ehrlichia ruminantium, the obligate intracellular bacterium that causes heartwater. A preliminary whole proteome analysis of elementary bodies, the extracellular infectious form of the bacterium, had been performed previously, but information is limited about OMPs in this organism and about their role in the protective immune response. Identification of OMPs is also essential for understanding Ehrlichia's OM architecture, and how the bacterium interacts with the host cell environment. First, we developed an OMP extraction method using the ionic detergent sarkosyl, which enriched the OM fraction. Second, proteins were separated via one-dimensional electrophoresis, and digested peptides were analyzed via nano-liquid chromatographic separation coupled with mass spectrometry (LC-MALDI-TOF/TOF). Of 46 unique proteins identified in the OM fraction, 18 (39%) were OMPs, including 8 proteins involved in cell structure and biogenesis, 4 in transport/virulence, 1 porin, and 5 proteins of unknown function. These experimental data were compared to the predicted subcellular localization of the entire E. ruminantium proteome, using three different algorithms. This work represents the most complete proteome characterization of the OM fraction in Ehrlichia spp. The study indicates that suitable subcellular fractionation experiments combined with straightforward computational analysis approaches are powerful for determining the predominant subcellular localization of the experimentally observed proteins. We identified proteins potentially involved in E. ruminantium pathogenesis, which are good novel targets for candidate vaccines. Thus, combining bioinformatics and proteomics, we discovered new OMPs for E. ruminantium that are valuable data for those investigating new vaccines against this organism. In summary, we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium.
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Affiliation(s)
- Amal Moumène
- CIRAD, UMR CMAEE, Site de Duclos, Prise d’eau, F-97170, Petit-Bourg, Guadeloupe, France
- INRA, UMR1309 CMAEE, F-34398, Montpellier, France
- Université des Antilles et de la Guyane, 97159, Pointe-à-Pitre cedex, Guadeloupe, France
| | - Isabel Marcelino
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Miguel Ventosa
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Olivier Gros
- Université des Antilles et de la Guyane, Institut de Biologie Paris Seine, UMR7138 UPMC-CNRS, Equipe Biologie de la Mangrove, UFR des Sciences Exactes et Naturelles, Département de Biologie, BP 592, 97159, Pointe-à-Pitre cedex, Guadeloupe, France
| | | | - Nathalie Vachiéry
- CIRAD, UMR CMAEE, Site de Duclos, Prise d’eau, F-97170, Petit-Bourg, Guadeloupe, France
- INRA, UMR1309 CMAEE, F-34398, Montpellier, France
| | - Damien F. Meyer
- CIRAD, UMR CMAEE, Site de Duclos, Prise d’eau, F-97170, Petit-Bourg, Guadeloupe, France
- INRA, UMR1309 CMAEE, F-34398, Montpellier, France
- * E-mail:
| | - Ana V. Coelho
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
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Jori F, Godfroid J, Michel AL, Potts AD, Jaumally MR, Sauzier J, Roger M. An assessment of Zoonotic and Production Limiting Pathogens in Rusa Deer (Cervus timorensis rusa) from Mauritius. Transbound Emerg Dis 2013; 61 Suppl 1:31-42. [DOI: 10.1111/tbed.12206] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Indexed: 11/28/2022]
Affiliation(s)
- F. Jori
- Integrated Animal Risk Management Unit (AGIRs); International Agricultural Research Centre for Development (CIRAD); Montpellier France
- Mammal Research Institute; Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
- Department of Animal Science and Production; Botswana College of Agriculture; Gaborone Botswana
| | - J. Godfroid
- Department of Food Safety and Infection Biology; Norwegian School of Veterinary Science; Tromsø Norway
- Department of Veterinary Tropical Diseases; Faculty of Veterinary Science; University of Pretoria; Pretoria South Africa
| | - A. L. Michel
- Department of Veterinary Tropical Diseases; Faculty of Veterinary Science; University of Pretoria; Pretoria South Africa
- Bacteriology Section; ARC-Onderstepoort Veterinary Institute; Pretoria South Africa
| | - A. D. Potts
- Bacteriology Section; ARC-Onderstepoort Veterinary Institute; Pretoria South Africa
| | | | - J. Sauzier
- Mauritius Deer Farming Cooperative Society Ltd; Curepipe Mauritius
| | - M. Roger
- Integrated Animal Risk Management Unit (AGIRs); International Agricultural Research Centre for Development (CIRAD); Montpellier France
- Centre de Recherche et de veille sur les maladies émergentes dans l'Océan Indien (CRVOI); Sainte Clotilde La Réunion
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Lobanov VA, Gajadhar AA, Al-Adhami B, Schwantje HM. Molecular study of free-ranging mule deer and white-tailed deer from British Columbia, Canada, for evidence of Anaplasma spp. and Ehrlichia spp. Transbound Emerg Dis 2011; 59:233-43. [PMID: 21933360 DOI: 10.1111/j.1865-1682.2011.01259.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Twenty-three free-ranging white-tailed deer (WTD; Odocoileus virginianus) and six mule deer (MD; Odocoileus hemionus) from south-central British Columbia, Canada, were tested for Anaplasma marginale by msp5 gene-specific PCR and Ehrlichia spp. by 16S rRNA or citrate synthase (gltA) gene-specific PCR, as well as by PCR with universal 16S rRNA primers detecting a wide range of bacteria. No deer tested positive for A. marginale. Amplification with universal 16S rRNA primers followed by sequencing of cloned fragments detected an Anaplasma sp. in one of 23 (4.3%) WTD and six of six (100%) MD and Bartonella sp. in four of 23 (17.4%) WTD. The Anaplasma sp. was genetically distinct from A. marginale and all other recognized members of the genus. Four of six (66.7%) MD and 0 of 23 (0%) WTD were Ehrlichia positive by PCR with primers for 16S rRNA and gltA genes. The sequences of gltA PCR fragments were identical to each other and to the respective region of the gltA gene of an Ehrlichia sp. which we detected previously in naturally infected cattle from the same area, suggesting the possibility of biological transmission of this rickettsia between cattle and wild cervids. Antibodies reactive with the MSP5 protein of A. marginale were detected using a competitive enzyme-linked immunosorbent assay in two of six (33.3%) MD, but not in WTD. The two seropositive MD were PCR positive for both the Anaplasma sp. and Ehrlichia sp. detected in this study, suggesting a reaction of antibodies against one or both of these rickettsias with the MSP5 antigen.
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Affiliation(s)
- V A Lobanov
- Canadian Food Inspection Agency, Centre for Food-Borne and Animal Parasitology, Saskatoon, SK, Canada
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Vieira RFDC, Biondo AW, Guimarães AMS, Dos Santos AP, Dos Santos RP, Dutra LH, Diniz PPVDP, de Morais HA, Messick JB, Labruna MB, Vidotto O. Ehrlichiosis in Brazil. ACTA ACUST UNITED AC 2011; 20:1-12. [PMID: 21439224 DOI: 10.1590/s1984-29612011000100002] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 11/03/2010] [Indexed: 11/21/2022]
Abstract
Ehrlichiosis is a disease caused by rickettsial organisms belonging to the genus Ehrlichia. In Brazil, molecular and serological studies have evaluated the occurrence of Ehrlichia species in dogs, cats, wild animals and humans. Ehrlichia canis is the main species found in dogs in Brazil, although E. ewingii infection has been recently suspected in five dogs. Ehrlichia chaffeensis DNA has been detected and characterized in mash deer, whereas E. muris and E. ruminantium have not yet been identified in Brazil. Canine monocytic ehrlichiosis caused by E. canis appears to be highly endemic in several regions of Brazil, however prevalence data are not available for several regions. Ehrlichia canis DNA also has been detected and molecularly characterized in three domestic cats, and antibodies against E. canis were detected in free-ranging Neotropical felids. There is serological evidence suggesting the occurrence of human ehrlichiosis in Brazil but its etiologic agent has not yet been established. Improved molecular diagnostic resources for laboratory testing will allow better identification and characterization of ehrlichial organisms associated with human ehrlichiosis in Brazil.
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Pfitzer S, Oosthuizen M, Bosman AM, Vorster I, Penzhorn B. Tick-borne blood parasites in nyala (Tragelaphus angasii, Gray 1849) from KwaZulu-Natal, South Africa. Vet Parasitol 2011; 176:126-31. [DOI: 10.1016/j.vetpar.2010.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 11/01/2010] [Accepted: 11/08/2010] [Indexed: 11/30/2022]
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Oura CAL, Tait A, Asiimwe B, Lubega GW, Weir W. Haemoparasite prevalence and Theileria parva strain diversity in Cape buffalo (Syncerus caffer) in Uganda. Vet Parasitol 2010; 175:212-9. [PMID: 21074945 DOI: 10.1016/j.vetpar.2010.10.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 10/09/2010] [Accepted: 10/12/2010] [Indexed: 11/30/2022]
Abstract
Cape buffalo (Syncerus caffer) are considered to be an important reservoir for various tick-borne haemoparasites of veterinary importance. In this study we have compared the haemoparasite carrier prevalence in buffalo from four geographically isolated national parks in Uganda [Lake Mburo National Park (LMNP), Queen Elizabeth National Park (QENP), Murchison Falls National Park (MFNP) and Kidepo Valley National Park (KVNP)]. Differences were seen in haemoparasite prevalence in buffalo from the four national parks. All the buffalo sampled in LMNP were carriers of Theileria parva however, buffalo from MFNP and KVNP, which are both located in the north of Uganda, were negative for T. parva. Interestingly, 95% of buffalo in the northern part of QENP were T. parva positive, however all buffalo sampled in the south of the park were negative. A high multiplicity of infection was recorded in all the buffalo found to be carrying T. parva, with evidence of at least nine parasite genotypes in some animals. Most of the buffalo sampled in all four national parks were carriers of T. mutans and T. velifera, however none were carriers of T. taurotragi, Babesia bovis, Babesia bigemina, Ehrlichia bovis or Ehrlichia ruminantium. All the buffalo sampled from LMNP were positive for T. buffeli and T. sp. (buffalo) however, buffalo from the parks in the north of the country (KVNP and MFNP) were negative for these haemoparasites. Anaplasma centrale and Anaplasma marginale were circulating in buffalo from all four national parks. T. parva gene pools from two geographically separated populations of buffalo in two of the national parks in Uganda (LMNP and QENP) were compared. The T. parva populations in the two national parks were distinct, indicating that there was limited gene flow between the populations. The results presented highlight the complexity of tick-borne pathogen infections in buffalo and the significant role that buffalo may play as reservoir hosts for veterinary haemoparasites that have the potential to cause severe disease in domestic cattle.
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Affiliation(s)
- C A L Oura
- Department of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Makerere, P.O. Box 7062, Kampala, Uganda.
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Kasari TR, Miller RS, James AM, Freier JE. Recognition of the threat of Ehrlichia ruminantium infection in domestic and wild ruminants in the continental United States. J Am Vet Med Assoc 2010; 237:520-30. [PMID: 20807129 DOI: 10.2460/javma.237.5.520] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Thomas R Kasari
- National Surveillance Unit, Centers for Epidemiology and Animal Health, Veterinary Services, APHIS, USDA, 2150 Centre Ave, Building B, Fort Collins, CO 80526, USA.
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Raliniaina M, Meyer DF, Pinarello V, Sheikboudou C, Emboulé L, Kandassamy Y, Adakal H, Stachurski F, Martinez D, Lefrançois T, Vachiéry N. Mining the genetic diversity of Ehrlichia ruminantium using map genes family. Vet Parasitol 2010; 167:187-95. [DOI: 10.1016/j.vetpar.2009.09.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Ehrlichia ruminantium is an obligately intracellular proteobacterium which causes a disease known as heartwater or cowdriosis in some wild, and all domestic, ruminants. The organism is transmitted by ticks of the genus Amblyomma, and it is of serious economic importance wherever the natural vectors occur, an area which includes all of sub-Saharan Africa, and several islands in the Caribbean. The disease was first recognized in South Africa in the 19th century, where its tick-borne nature was determined in 1900, but the organism itself was not demonstrated until 1925, when it was recognized to be a rickettsia, initially named Rickettsia ruminantium. It was thus the first species of what are now known as Ehrlichia to be discovered, and most of the early work to elucidate the nature of the organisms, and its reservoirs and vectors, was performed in South Africa. The next milestone was the development, in 1945, of an infection and treatment regimen to immunize livestock, and this is still the only commercially available "vaccine" against the disease. Then in 1985, after fruitless attempts over many years, the organism was propagated reliably in tissue culture, opening the way for the first application of the newly developed techniques of molecular genetics. From 1990 onwards the pace of heartwater research accelerated rapidly, with notable advances in phylogeny, diagnosis, epidemiology, immunology, and vaccine development. The complete genome sequence was published in 2005, and during the last two years a new understanding has arisen of the remarkable genetic variability of the organism and new experimental vaccines have been developed. Despite all this the goal of producing an effective vaccine against the disease in the field still remains frustratingly just beyond reach. This article summarises our current understanding of the nature of E. ruminantium, at a time when the prospects for the development of an effective vaccine against the organism seem better than at any time since its discovery 83 years ago.
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Affiliation(s)
- Basil A Allsopp
- Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort 0110, South Africa.
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Loftis AD, Mixson TR, Stromdahl EY, Yabsley MJ, Garrison LE, Williamson PC, Fitak RR, Fuerst PA, Kelly DJ, Blount KW. Geographic distribution and genetic diversity of the Ehrlichia sp. from Panola Mountain in Amblyomma americanum. BMC Infect Dis 2008; 8:54. [PMID: 18433500 PMCID: PMC2394526 DOI: 10.1186/1471-2334-8-54] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 04/23/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A novel Ehrlichia, closely related to Ehrlichia ruminantium, was recently discovered from Panola Mountain State Park, GA, USA. We conducted a study to determine if this agent was recently introduced into the United States. METHODS We developed a sensitive PCR assay based on the conserved gltA (citrate synthase) gene and tested DNA samples extracted from 1964 field-collected and 1835 human-biting Amblyomma americanum from 23 eastern states of the USA. RESULTS The novel agent was detected in 36 ticks collected from 10 states between 1998 and 2006. Infected ticks were collected both from vegetation (n = 14, 0.7%) and from humans (n = 22, 1.2%). Fragments of the conserved gltA gene and the variable map1 gene were sequenced from positive samples. Two distinct clades, with 10.5% nucleic acid divergence over the 730 bp map1 sequence, were identified. CONCLUSION These data suggest that the Panola Mountain Ehrlichia was not recently introduced to the United States; this agent has an extensive distribution throughout the range of its tick vector, has been present in some locations for several years, and displays genetic variability. Furthermore, people in several states were exposed to this agent through the bite of infected ticks, underscoring the potential public health risk of this emerging ehrlichiosis.
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Affiliation(s)
- Amanda D Loftis
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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Feng HM, Walker DH. Mechanisms of immunity to Ehrlichia muris: a model of monocytotropic ehrlichiosis. Infect Immun 2004; 72:966-71. [PMID: 14742542 PMCID: PMC321622 DOI: 10.1128/iai.72.2.966-971.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia species can cause life-threatening infections or chronic persistent infections. Mechanisms of protective immunity were examined in an Ehrlichia muris mouse model of monocytotropic ehrlichiosis. C57BL/6 mice possessed strong genetic resistance to E. muris of an undetermined mechanism. CD8 T lymphocytes were particularly important, as revealed by 81% fatalities for E. muris-infected, major histocompatibility complex class I gene knockout mice compared with no deaths for wild-type C3H mice. Moreover, 80% of C3H mice depleted of CD8 and CD4 cells died of E. muris infection compared with only 44% of CD4 cell-depleted mice. CD8 T lymphocytes were demonstrated for the first time in an Ehrlichia infection to exhibit cytotoxic T-lymphocyte activity against Ehrlichia-infected target cells. Both gamma interferon and tumor necrosis factor were shown to play synergistic roles in protective immunity in vivo for the first time, as demonstrated by 75% fatalities when both cytokines were neutralized compared with minimal mortality when they were depleted separately. Passive transfer of antibodies, but not Fab fragments, to E. muris protected C3H/SCID mice against lethal infection. The mechanism of increased susceptibility (22% lethality) of C57BL/6 major histocompatibility complex class II gene knockout mice and CD4 cell-depleted C3H mice (i.e., through a gamma interferon or antibody mechanism), as well as the more important role of CD8 T lymphocytes (in the form of cytotoxic T-lymphocyte activity and/or gamma interferon production), remains to be elucidated. Protective immunity against monocytotropic E. muris is mediated by a combination of CD8 and CD4 T lymphocytes, gamma interferon, tumor necrosis factor alpha, and antibodies.
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Affiliation(s)
- Hui-Min Feng
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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