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Wilson AG, Lapen DR, Provencher JF, Wilson S. The role of species ecology in predicting Toxoplasma gondii prevalence in wild and domesticated mammals globally. PLoS Pathog 2024; 20:e1011908. [PMID: 38198498 PMCID: PMC10805296 DOI: 10.1371/journal.ppat.1011908] [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: 09/18/2023] [Revised: 01/23/2024] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Macroecological approaches can provide valuable insight into the epidemiology of globally distributed, multi-host pathogens. Toxoplasma gondii is a protozoan that infects any warm-blooded animal, including humans, in almost every habitat worldwide. Toxoplasma gondii infects its hosts through oocysts in the environment, carnivory of tissue cysts within intermediate host prey and vertical transmission. These routes of infection enable specific predictions regarding the ecological and life history traits that should predispose specific taxa to higher exposure and, thus infection rates of T. gondii. Using T. gondii prevalence data compiled from 485 studies representing 533 free-ranging wild mammalian species, we examined how ecological (habitat type, trophic level) and life history (longevity, vagility, gestation duration and torpor) traits influence T. gondii infection globally. We also compared T. gondii prevalence between wild and domesticated species from the same taxonomic families using data compiled from 540 studies of domestic cattle, sheep, and pigs. Across free-ranging wildlife, we found the average T. gondii prevalence was 22%, which is comparable to the global human estimate. Among ecological guilds, terrestrial species had lower T. gondii prevalence than aquatic species, with freshwater aquatic taxa having an increased prevalence compared to marine aquatic species. Dietary niches were also influential, with carnivores having an increased risk compared to other trophic feeding groups that have reduced tissue cyst exposure in their diet. With respect to influential life history traits, we found that more vagile wildlife species had higher T. gondii infection rates, perhaps because of the higher cumulative risk of infection during movement through areas with varying T. gondii environmental loads. Domestic farmed species had a higher T. gondii prevalence compared to free-ranging confamilial wildlife species. Through a macroecological approach, we determined the relative significance of transmission routes of a generalist pathogen, demonstrating an increased infection risk for aquatic and carnivorous species and highlighting the importance of preventing pathogen pollution into aquatic environments. Toxoplasma gondii is increasingly understood to be primarily an anthropogenically-associated pathogen whose dissemination is enhanced by ecosystem degradation and human subsidisation of free-roaming domestic cats. Adopting an ecosystem restoration approach to reduce one of the world's most common parasites would synergistically contribute to other initiatives in conservation, feline and wildlife welfare, climate change, food security and public health.
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Affiliation(s)
- Amy G. Wilson
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - David R. Lapen
- Agriculture and Agri-Food Canada/Agriculture et Agroalimentaire Canada, Ottawa Research Development Centre, Ottawa, Ontario, Canada
| | - Jennifer F. Provencher
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario, Canada
| | - Scott Wilson
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Wildlife Research Division, Environment and Climate Change, Pacific Wildlife Research Centre, Delta, British Columbia, Canada
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Antolová D, Stanko M, Jarošová J, Miklisová D. Rodents as Sentinels for Toxoplasma gondii in Rural Ecosystems in Slovakia-Seroprevalence Study. Pathogens 2023; 12:826. [PMID: 37375516 DOI: 10.3390/pathogens12060826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Toxoplasma gondii is a ubiquitous intracellular parasite with felids as definitive hosts and a broad range of intermediate hosts. Rodents are considered suitable sentinels for prevalence studies of many infections, including toxoplasmosis. This study aimed to estimate the seroprevalence of T. gondii in rodents from different localities of Slovakia and investigate the correlation between the seropositivity and the species, age, sex, and sexual activity of animals. Altogether, 1009 wild rodents belonging to 9 species were trapped in 2015 and 2019, and antibodies to T. gondii were detected in 6.7% of the animals. Seropositivity was detected in seven species, ranging from 0.0% in Micromys minutus and Apodemus sylvaticus to 7.7% in A. flavicollis. The females reached significantly higher seropositivity (9.7%) than the males (3.8%), and the adults were positive significantly more often (9.2%) than the subadults (4.9%). The seropositivity differed also among localities, with significantly higher positivity detected in suburban and touristic areas (12.2%) than in localities with a lower level of human activities (5.5%). This study showed that the occurrence of T. gondii varies significantly in rodent species and habitats with various environmental conditions and different levels of anthropic use. Several biological and ecological factors, e.g., soil contamination, soil conditions, the susceptibility of rodent species etc., may influence this variability.
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Affiliation(s)
- Daniela Antolová
- Institute of Parasitology SAS, Hlinkova 3, 040 01 Košice, Slovakia
| | - Michal Stanko
- Institute of Parasitology SAS, Hlinkova 3, 040 01 Košice, Slovakia
| | - Júlia Jarošová
- Institute of Parasitology SAS, Hlinkova 3, 040 01 Košice, Slovakia
| | - Dana Miklisová
- Institute of Parasitology SAS, Hlinkova 3, 040 01 Košice, Slovakia
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PARASITES OF AN ENDANGERED HARVEST MOUSE (REITHRODONTOMYS RAVIVENTRIS HALICOETES) IN A NORTHERN CALIFORNIA MARSH. J Wildl Dis 2021; 58:122-136. [PMID: 34814173 DOI: 10.7589/jwd-d-21-00059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/15/2021] [Indexed: 11/20/2022]
Abstract
Disease may limit recovery of endangered species. We surveyed parasites in the federally endangered salt marsh harvest mouse (SMHM; Reithrodontomys raviventris halicoetes) and sympatric rodents in Suisun Marsh (Solano County, California, USA) from April 2018 through March 2019. We investigated individual SMHM risk factors (age, sex, reproductive status, and body condition) for infection and relationships among the estimated parasite prevalence and season and habitat management (natural tidal habitats versus diked, nontidal habitats). We captured 625 individual rodents, including 439 SMHM, and tested these for infection with Bartonella spp., Borrelia spp., Rickettsia spp., Francisella tularensis, Leptospira spp., Cryptosporidium spp., Giardia spp., and Toxoplasma gondii by PCR. Over one-third (34.6%, confidence interval [CI], 30.2%-39.3%) of SMHM tested positive for at least one parasite. Four percent (CI, 2.8%-6.3%) of SMHM were infected with F. tularensis holarctica, a virulent bacterium that causes mortality in rodents shortly after infection. Additionally, we detected three species of Bartonella (B. henselae, B. rochalimae, B. vinsonii arupensis), Leptospira borgpetersenii serovar Ballum, Cryptosporidium sp. (deer mouse [Peromyscus maniculatus] genotype), Cryptosporidium parvum, Giardia intestinalis, and an unidentified Borrelia sp. The only parasite that was associated with habitat management was Bartonella spp., which was more prevalent in diked than tidal areas. Male SMHM were more likely to be parasitized than females, and individuals in modestly poor body condition were most likely to be infected with Bartonella spp. The estimated sample prevalence of multiple parasites varied by season and by host species. This is the first major parasite assessment in a long-endangered species, and these results will assist managers to incorporate parasitic disease into recovery planning and provide a critical baseline for future investigations, including how climatically induced habitat and species composition changes could alter disease dynamics.
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TRANSMISSION DYNAMICS OF TOXOPLASMA GONDII IN ARCTIC FOXES (VULPES LAGOPUS): A LONG-TERM MARK-RECAPTURE SEROLOGIC STUDY AT KARRAK LAKE, NUNAVUT, CANADA. J Wildl Dis 2019; 55:619-626. [DOI: 10.7589/2018-06-144] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Human impact on the diversity and virulence of the ubiquitous zoonotic parasite Toxoplasma gondii. Proc Natl Acad Sci U S A 2018; 115:E6956-E6963. [PMID: 29967142 PMCID: PMC6055184 DOI: 10.1073/pnas.1722202115] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A majority of emerging infectious diseases in humans are zoonoses. Understanding factors that influence the emergence and transmission of zoonoses is pivotal for their prevention and control. Toxoplasma gondii is one of the most widespread zoonotic pathogens known today. Whereas only a few genotypes of T. gondii dominate in the Northern Hemisphere, many genotypes coexist in South America. Furthermore, T. gondii strains from South America are more likely to be virulent than those from the Northern Hemisphere. However, it is not clear what factor(s) shaped modern-day genetic diversity and virulence of T. gondii Here, our analysis suggests that the rise and expansion of farming in the past 11,000 years established the domestic cat/mouse transmission cycle for T. gondii, which has undoubtedly played a significant role in the selection of certain linages of T. gondii Our mathematical simulations showed that within the domestic transmission cycle, intermediately mouse-virulent T. gondii genotypes have an adaptive advantage and eventually become dominant due to a balance between lower host mortality and the ability to superinfect mice previously infected with a less virulent T. gondii strain. Our analysis of the global type II lineage of T. gondii suggests its Old World origin but recent expansion in North America, which is likely the consequence of global human migration and trading. These results have significant implications concerning transmission and evolution of zoonotic pathogens in the rapidly expanding anthropized environment demanded by rapid growth of the human population and intensive international trading at present and in the future.
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Antonovics J, Wilson AJ, Forbes MR, Hauffe HC, Kallio ER, Leggett HC, Longdon B, Okamura B, Sait SM, Webster JP. The evolution of transmission mode. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0083. [PMID: 28289251 PMCID: PMC5352810 DOI: 10.1098/rstb.2016.0083] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2016] [Indexed: 12/31/2022] Open
Abstract
This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode have been inferred through experimental and phylogenetic studies, including changes in transmission associated with host shifts and with evolution of the unusually complex life cycles of many parasites. Understanding the forces that determine the evolution of particular transmission modes presents a fascinating medley of problems for which there is a lack of good data and often a lack of conceptual understanding or appropriate methodologies. Our best information comes from studies that have been focused on the vertical versus horizontal transmission dichotomy. With other kinds of transitions, theoretical approaches combining epidemiology and population genetics are providing guidelines for determining when and how rapidly new transmission modes may evolve, but these are still in need of empirical investigation and application to particular cases. Obtaining such knowledge is a matter of urgency in relation to extant disease threats.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
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Affiliation(s)
- Janis Antonovics
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Anthony J Wilson
- Integrative Entomology group, Vector-borne Viral Diseases programme, The Pirbright Institute, Pirbright GU24 0NF, UK
| | - Mark R Forbes
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B7
| | - Heidi C Hauffe
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S. Michele all'Adige, Trentino, Italy
| | - Eva R Kallio
- Department of Biological and Environmental Science, University of Jyvaskyla, PO Box 35, 40014 Jyvaskyla, Finland.,Department of Ecology, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - Helen C Leggett
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Ben Longdon
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Beth Okamura
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW5 7BD, UK
| | - Steven M Sait
- School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Joanne P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, London AL9 7TA, UK
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Webster JP, Borlase A, Rudge JW. Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the 'elimination' era. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160091. [PMID: 28289259 PMCID: PMC5352818 DOI: 10.1098/rstb.2016.0091] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2016] [Indexed: 12/21/2022] Open
Abstract
Multi-host infectious agents challenge our abilities to understand, predict and manage disease dynamics. Within this, many infectious agents are also able to use, simultaneously or sequentially, multiple modes of transmission. Furthermore, the relative importance of different host species and modes can itself be dynamic, with potential for switches and shifts in host range and/or transmission mode in response to changing selective pressures, such as those imposed by disease control interventions. The epidemiology of such multi-host, multi-mode infectious agents thereby can involve a multi-faceted community of definitive and intermediate/secondary hosts or vectors, often together with infectious stages in the environment, all of which may represent potential targets, as well as specific challenges, particularly where disease elimination is proposed. Here, we explore, focusing on examples from both human and animal pathogen systems, why and how we should aim to disentangle and quantify the relative importance of multi-host multi-mode infectious agent transmission dynamics under contrasting conditions, and ultimately, how this can be used to help achieve efficient and effective disease control.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
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Affiliation(s)
- Joanne P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Hatfield AL9 7TA, UK
| | - Anna Borlase
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Hatfield AL9 7TA, UK
| | - James W Rudge
- Communicable Diseases Policy Research Group, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
- Faculty of Public Health, Mahidol University, 420/1 Rajavithi Road, Bangkok 10400, Thailand
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PREVALENCE AND POTENTIAL IMPACT OFTOXOPLASMA GONDIION THE ENDANGERED AMARGOSA VOLE (MICROTUS CALIFORNICUS SCIRPENSIS), CALIFORNIA, USA. J Wildl Dis 2017; 53:62-72. [DOI: 10.7589/2015-12-349] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Hide G. Role of vertical transmission of Toxoplasma gondii in prevalence of infection. Expert Rev Anti Infect Ther 2016; 14:335-44. [PMID: 26807498 DOI: 10.1586/14787210.2016.1146131] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The parasite, Toxoplasma gondii, is a highly successful pathogen that infects around 30% of the global human population. Additionally, it is able to infect all warm blooded animals with high prevalence. This is surprising as it is a parasite of the cat and can only complete its full sexual cycle in that host. This review examines the important key routes of transmission: infective oocysts from the cat, ingestion of raw infected tissue and vertical transmission. The latter route of transmission has traditionally been thought to be rare. In this review, this assumption is examined and discussed in the light of the current literature. The available evidence points to the possibility that vertical transmission occurs frequently in natural populations of mice however the evidence in sheep is currently ambivalent and controversial. In humans, the situation appears as though vertical transmission may be rare although there is still much that is unexplained.
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Affiliation(s)
- Geoff Hide
- a Ecosystems and Environment Research Centre and Biomedical Research Centre, School of Environment and Life Sciences , University of Salford , Salford , UK
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10
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Dual congenital transmission of Toxoplasma gondii and Sarcocystis neurona in a late-term aborted pup from a chronically infected southern sea otter (Enhydra lutris nereis). Parasitology 2015; 143:276-88. [PMID: 26494610 DOI: 10.1017/s0031182015001377] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Toxoplasma gondii and Sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. Close monitoring of threatened southern sea otters (Enhydra lutris nereis) in California allowed for the diagnosis of dual transplacental transmission of T. gondii and S. neurona in a wild female otter that was chronically infected with both parasites. Congenital infection resulted in late-term abortion due to disseminated toxoplasmosis. Toxoplasma gondii and S. neurona DNA was amplified from placental tissue culture, as well as from fetal lung tissue. Molecular characterization of T. gondii revealed a Type X genotype in isolates derived from placenta and fetal brain, as well as in all tested fetal organs (brain, lung, spleen, liver and thymus). This report provides the first evidence for transplacental transmission of T. gondii in a chronically infected wild sea otter, and the first molecular and immunohistochemical confirmation of concurrent transplacental transmission of T. gondii and S. neurona in any species. Repeated fetal and/or neonatal losses in the sea otter dam also suggested that T. gondii has the potential to reduce fecundity in chronically infected marine mammals through parasite recrudescence and repeated fetal infection.
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Elmore S, Samelius G, Fernando C, Alisauskas R, Jenkins E. Evidence for Toxoplasma gondii in migratory vs. nonmigratory herbivores in a terrestrial arctic ecosystem. CAN J ZOOL 2015. [DOI: 10.1139/cjz-2015-0078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is currently unclear how Toxoplasma gondii (Nicolle and Manceaux, 1908) persists in arctic tundra ecosystems in the absence of felid definitive hosts. To investigate potential transmission routes of T. gondii in a terrestrial arctic food web, we collected samples from two migratory herbivores, Ross’s Geese (Chen rossi (Cassin, 1861)) and Lesser Snow Geese (Chen caerulescens (L., 1758)), and from two resident herbivores, Nearctic brown lemmings (Lemmus trimucronatus (Richardson, 1825)) and collared lemmings (Dicrostonyx groenlandicus (Traill, 1823)), trapped at Karrak Lake, Nunavut, Canada. Antibodies were detected in 76 of 234 (32.4%) serum samples from Ross’s Geese and 66 of 233 (28.3%) serum samples from Lesser Snow Geese. We did not detect T. gondii antibodies in filter-paper eluate tested from thoracic fluid samples collected from 84 lemmings. We did not detect T. gondii DNA in brain tissue from these lemmings. Although a small sample size, our findings suggest that lemmings in this terrestrial arctic ecosystem are not exposed to, or infected with, the parasite. This suggests that oocysts are not introduced into the terrestrial arctic ecosystem at Karrak Lake via freshwater runoff from temperate regions. This study demonstrated that live adult arctic-nesting geese are exposed to T. gondii and therefore migratory herbivorous hosts are potential sources of T. gondii infection for predators in terrestrial arctic ecosystems.
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Affiliation(s)
- S.A. Elmore
- Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada
| | - G. Samelius
- Snow Leopard Trust, 4649 Sunnyside Avenue North, Suite 325, Seattle, WA 98103, USA
| | - C. Fernando
- Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada
| | - R.T. Alisauskas
- Environment Canada, Prairie and Northern Wildlife Research Centre, 115 Perimeter Road, Saskatoon, SK S7N 0X4, Canada
| | - E.J. Jenkins
- Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada
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EPIDEMIOLOGY AND PATHOLOGY OFTOXOPLASMA GONDIIIN FREE-RANGING CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS). J Wildl Dis 2015; 51:362-73. [DOI: 10.7589/2014-08-205] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Pathogen infection and exposure, and ectoparasites of the federally endangered Amargosa vole (Microtus californicus scirpensis), California, USA. J Wildl Dis 2014; 50:767-76. [PMID: 25121407 DOI: 10.7589/2013-09-248] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract We surveyed pathogens and ectoparasites among federally endangered Amargosa voles (Microtus californicus scirpensis) and sympatric rodents in Tecopa Hot Springs, Inyo County, California, December 2011-November 2012. We aimed to assess disease and detect possible spillover from or connectivity with other hosts within and outside the Amargosa ecosystem. We assessed 71 individual voles and 38 individual sympatric rodents for current infection with seven vector-borne zoonotic pathogens and past exposure to five pathogens. Thirteen percent of Amargosa voles were PCR positive for Toxoplasma gondii, a zoonotic protozoan that may alter host behavior or cause mortality. Additionally, we found antibodies against Borrelia burgdorferi sensu lato (SL) spp. in 21% of voles, against Anaplasma phagocytophilum in 2.6%, Rickettsia spp. in 13%, relapsing fever Borrelia (3.9%), and T. gondii (7.9%). Sympatric rodents also had active infections with Borrelia SL spp. (15%). Of the ectoparasites collected, the tick Ixodes minor is of particular interest because the study area is well outside of the species' reported range and because I. minor ticks infest migratory birds as well as rodents, showing a potential mechanism for pathogens to be imported from outside the Amargosa ecosystem.
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Congenital Toxoplasmosis in Wild Boar (Sus scrofa) and Identification of theToxoplasma gondiiTypes Involved. J Wildl Dis 2013; 49:1019-23. [DOI: 10.7589/2013-01-024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Technical specifications on harmonised epidemiological indicators for biological hazards to be covered by meat inspection of domestic sheep and goats. EFSA J 2013. [DOI: 10.2903/j.efsa.2013.3277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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VanWormer E, Fritz H, Shapiro K, Mazet JAK, Conrad PA. Molecules to modeling: Toxoplasma gondii oocysts at the human-animal-environment interface. Comp Immunol Microbiol Infect Dis 2013; 36:217-31. [PMID: 23218130 PMCID: PMC3779781 DOI: 10.1016/j.cimid.2012.10.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 10/17/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Environmental transmission of extremely resistant Toxoplasma gondii oocysts has resulted in infection of diverse species around the world, leading to severe disease and deaths in human and animal populations. This review explores T. gondii oocyst shedding, survival, and transmission, emphasizing the importance of linking laboratory and landscape from molecular characterization of oocysts to watershed-level models of oocyst loading and transport in terrestrial and aquatic systems. Building on discipline-specific studies, a One Health approach incorporating tools and perspectives from diverse fields and stakeholders has contributed to an advanced understanding of T. gondii and is addressing transmission at the rapidly changing human-animal-environment interface.
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Affiliation(s)
- Elizabeth VanWormer
- One Health Institute, School of Veterinary Medicine, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA.
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Proteomic analysis of fractionated Toxoplasma oocysts reveals clues to their environmental resistance. PLoS One 2012; 7:e29955. [PMID: 22279555 PMCID: PMC3261165 DOI: 10.1371/journal.pone.0029955] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/07/2011] [Indexed: 11/19/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that is unique in its ability to infect a broad range of birds and mammals, including humans, leading to an extremely high worldwide prevalence and distribution. This work focuses on the environmentally resistant oocyst, which is the product of sexual replication in felids and an important source of human infection. Due to the difficulty in producing and working with oocysts, relatively little is known about how this stage is able to resist extreme environmental stresses and how they initiate a new infection, once ingested. To fill this gap, the proteome of the wall and sporocyst/sporozoite fractions of mature, sporulated oocysts were characterized using one-dimensional gel electrophoresis followed by LC-MS/MS on trypsin-digested peptides. A combined total of 1021 non-redundant T. gondii proteins were identified in the sporocyst/sporozoite fraction and 226 were identified in the oocyst wall fraction. Significantly, 172 of the identified proteins have not previously been identified in Toxoplasma proteomic studies. Among these are several of interest for their likely role in conferring environmental resistance including a family of small, tyrosine-rich proteins present in the oocyst wall fractions and late embryogenesis abundant domain-containing (LEA) proteins in the cytosolic fractions. The latter are known from other systems to be key to enabling survival against desiccation.
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Elmore SA, Jenkins EJ, Huyvaert KP, Polley L, Root JJ, Moore CG. Toxoplasma gondiiin Circumpolar People and Wildlife. Vector Borne Zoonotic Dis 2012; 12:1-9. [DOI: 10.1089/vbz.2011.0705] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Stacey A. Elmore
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan
| | - Emily J. Jenkins
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan
| | - Kathryn P. Huyvaert
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado
| | - Lydden Polley
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan
| | - J. Jeffrey Root
- United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado
| | - Chester G. Moore
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado
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Fritz H, Barr B, Packham A, Melli A, Conrad PA. Methods to produce and safely work with large numbers of Toxoplasma gondii oocysts and bradyzoite cysts. J Microbiol Methods 2011; 88:47-52. [PMID: 22037023 DOI: 10.1016/j.mimet.2011.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 10/13/2011] [Accepted: 10/13/2011] [Indexed: 10/16/2022]
Abstract
Two major obstacles to conducting studies with Toxoplasma gondii oocysts are the difficulty in reliably producing large numbers of this life stage and safety concerns because the oocyst is the most environmentally resistant stage of this zoonotic organism. Oocyst production requires oral infection of the definitive feline host with adequate numbers of T. gondii organisms to obtain unsporulated oocysts that are shed in the feces for 3-10 days after infection. Since the most successful and common mode of experimental infection of kittens with T. gondii is by ingestion of bradyzoite tissue cysts, the first step in successful oocyst production is to ensure a high bradyzoite tissue cyst burden in the brains of mice that can be used for the oral inoculum. We compared two methods for producing bradyzoite brain cysts in mice, by infecting them either orally or subcutaneously with oocysts. In both cases, oocysts derived from a low passage T. gondii Type II strain (M4) were used to infect eight-ten week-old Swiss Webster mice. First the number of bradyzoite cysts that were purified from infected mouse brains was compared. Then to evaluate the effect of the route of oocyst inoculation on tissue cyst distribution in mice, a second group of mice was infected with oocysts by one of each route and tissues were examined by histology. In separate experiments, brains from infected mice were used to infect kittens for oocyst production. Greater than 1.3 billion oocysts were isolated from the feces of two infected kittens in the first production and greater than 1.8 billion oocysts from three kittens in the second production. Our results demonstrate that oral delivery of oocysts to mice results in both higher cyst loads in the brain and greater cyst burdens in other tissues examined as compared to those of mice that received the same number of oocysts subcutaneously. The ultimate goal in producing large numbers of oocysts in kittens is to generate adequate amounts of starting material for oocyst studies. Given the potential risks of working with live oocysts in the laboratory, we also tested a method of oocyst inactivation by freeze-thaw treatment. This procedure proved to completely inactivate oocysts without evidence of significant alteration of the oocyst molecular integrity.
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Affiliation(s)
- H Fritz
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, 1 Shields Avenue, University of California Davis, CA 95616, USA.
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Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats. Parasitology 2011; 138:1117-23. [PMID: 21756421 DOI: 10.1017/s0031182011000904] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%-47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%-67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses from pregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%-6·66%); M. domesticus: 3·08% (95% CI: 0·11%-6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems.
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