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Eads DA, Huyvaert KP, Biggins DE. Estimating parasite infrapopulation size given imperfect detection: Proof-of-concept with ectoparasitic fleas on prairie dogs. Int J Parasitol Parasites Wildl 2023; 20:117-121. [PMID: 36756090 PMCID: PMC9900500 DOI: 10.1016/j.ijppaw.2023.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/06/2023] [Accepted: 01/06/2023] [Indexed: 01/09/2023]
Abstract
Parasite infrapopulation size - the population of parasites affecting a single host - is a central metric in parasitology. However, parasites are small and elusive such that imperfect detection is expected. Repeated sampling of parasites during primary sampling occasions (e.g., each host capture) informs the detection process. Here, we estimate flea (Siphonaptera) infrapopulation size on black-tailed prairie dogs (Cynomys ludovicianus, BTPDs) as a proof-of-concept for estimating parasite infrapopulations given imperfect detection. From Jun-Aug 2011, we live-trapped 299 BTPDs for a total of 573 captures on 20 plots distributed among 13 colonies at the Vermejo Park Ranch, New Mexico, USA. During each capture, an anesthetized BTPD was combed 3 times consecutively, 15 s each, to remove and count fleas. Each flea (n = 4846) was linked to the BTPD from which it was collected and assigned an encounter history ('100', '010', '001'). We analyzed the encounter histories using Huggins closed captures models, setting recapture probabilities to 0, thereby accounting for flea removal from hosts. The probability of detecting an individual flea (p) increased with Julian date; field personnel may have become more efficient at combing fleas as the field season progressed. Combined p across 3 combings equaled 0.99. Estimates of flea infrapopulation size were reasonable and followed the negative binomial distribution. Our general approach may be broadly applicable to estimating infrapopulation sizes for parasites. The utility of this approach increases as p declines but, if p is very low, inference is likely limited.
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Affiliation(s)
- David A. Eads
- U. S. Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, CO, 80526, USA,Corresponding author. U. S. Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, CO, 80526, USA.
| | - Kathryn P. Huyvaert
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Dean E. Biggins
- U. S. Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, CO, 80526, USA
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2
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López-Pérez AM, Pesapane R, Clifford DL, Backus L, Foley P, Voll A, Silva RB, Foley J. Host species and environment drivers of ectoparasite community of rodents in a Mojave Desert wetlands. PLoS One 2022; 17:e0269160. [PMID: 35653332 PMCID: PMC9162374 DOI: 10.1371/journal.pone.0269160] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 05/16/2022] [Indexed: 12/16/2022] Open
Abstract
Drivers of patterns of ectoparasitism in rodents in patchy Mojave Desert wetlands were investigated. A total of 1,571 ectoparasites in Mesostigmata, Trombidiformes, Siphonaptera and Ixodida were collected from 341 rodents (Microtus californicus scirpensis, Mus musculus, Reithrodontomys megalotis, Peromyscus eremicus, and Neotoma lepida) at eleven marshes. Trombiculids accounted for 82.5% of mites, followed by the mesostigmatid Ornithonyssus bacoti (17.5%), with chiggers predominating on voles and harvest mice. There were at least three genera of chiggers (Eutrombicula alfreddugesi, Euschoengastia sp. novel, and Blankaartia sp. novel). Fleas included Orchopeas leucopus (90.3% of all fleas) and O. sexdentatus (9.7%), and ticks were the novel endemic Ixodes mojavensis (82.1% of ticks) and Dermacentor similis (17.9%). On all hosts and at all marshes, coverage-based rarefaction sampling was over 96%, indicating coverage sufficient for analysis. Dissimilarities in ectoparasite community structure were driven mainly by chiggers, I. mojavensis and O. leucopus. Northern marshes were dominated by chiggers; central marshes by I. mojavensis; and southern marshes by O. leucopus. Primary determinants of ectoparasite community structure were host species, patch size, and parasite interspecific interactions. Host species richness and environmental factors such as patch distance and water and plant availability were not significantly associated with patterns of ectoparasitism. There were nine (60%) significant negative pairwise associations between ectoparasite taxa and no significant positive relationships. Ixodes mojavensis had the highest number of negative associations (with five other species), followed by chiggers and O. bacoti with two negative associations each. The study area is among the most arid in North America and supports numerous rare and endemic species in increasingly isolated wetland habitat patches; knowledge of ectoparasite ecology in this region identifies potential ectoparasite vectors, and provides information needed to design and implement programs to manage vector-borne diseases for purposes of wildlife conservation.
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Affiliation(s)
- Andrés M. López-Pérez
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Risa Pesapane
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
- Department of Veterinary Preventive Medicine, School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio, United States of America
| | - Deana L. Clifford
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
- Wildlife Investigations Lab, California Department of Fish and Wildlife, Rancho Cordova, California, United States of America
| | - Laura Backus
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Patrick Foley
- Department of Biological Sciences, California State University Sacramento, Sacramento, California, United States of America
| | - Ashley Voll
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Ricardo Bassini Silva
- Zoological Collections Laboratory, Butantan Institute, Butantã, São Paulo, São Paulo, Brazil
- Faculty of Agrarian and Veterinary Sciences-UNESP, Department of Pathology, Reproduction and Unique Health, Jaboticabal, São Paulo, Brazil
| | - Janet Foley
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
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Antolin MF. From outbreaks to endemic disease. Science 2022; 376:453-454. [PMID: 35482884 DOI: 10.1126/science.abo7428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Relief from the effects of epidemics may signal the start of low-level disease persistence.
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Affiliation(s)
- Michael F Antolin
- Department of Biology, Colorado State University, Fort Collins, CO, USA
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5
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Augustine DJ, Derner JD. Long‐Term Effects of Black‐Tailed Prairie Dogs on Livestock Grazing Distribution and Mass Gain. J Wildl Manage 2021. [DOI: 10.1002/jwmg.22103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David J. Augustine
- Rangeland Resources and Systems Research Unit USDA‐ARS 1701 Centre Ave. Fort Collins CO 80526 USA
| | - Justin D. Derner
- Rangeland Resources and Systems Research Unit USDA‐ARS 8408 Hildreth Road Cheyenne WY 82009 USA
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6
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Belthoff JR, Elgin AA, Navock KA, Bernhardt SA. Burrowing owls as potential phoretic hosts of ground squirrel fleas during a plague epizootic. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2021; 46:48-56. [PMID: 35229581 DOI: 10.52707/1081-1710-46.1.48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/30/2020] [Indexed: 06/14/2023]
Abstract
During the course of a plague epizootic, decimation of rodent host populations may result in the transfer of fleas to alternate or phoretic hosts, including to sympatric raptors that prey on rodents. We studied flea abundance and flea species assemblages on burrowing owls (Athene cunicularia hypugaea) in southwestern Idaho before (2012 - 2014), during (2015 - 2016), and after (2017) an epizootic of plague in Piute ground squirrels (Urocitellis mollis). We examined (1) if a larger proportion of burrowing owl nests contained fleas, (2) the likelihood that owls within a high flea abundance class increased, and (3) if owls harbored ground squirrel fleas during the epizootic. Using a flea abundance index assigned to 1,184 owls from 236 nests, the proportion of nests and the likelihood that owls had high flea abundance decreased rather than increased during epizootic years. Moreover, of 3,538 collected fleas from owls at 143 nests, no fleas were species that Piute ground squirrels typically harbor. Instead, Pulex irritans was the predominant flea collected in all study years (> 99%). Thus, although raptors may play a role in plague, there was no evidence that the die-off of ground squirrels resulted in higher flea intensity in burrowing owls or that they served as frequent accidental or phoretic hosts for ground squirrel fleas that could potentially be infectious with Yersinia pestis.
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Affiliation(s)
- James R Belthoff
- REU Site in Raptor Research, Raptor Research Center and Department of Biological Sciences, Boise State University, Boise, ID, U.S.A.,
| | - Andrew A Elgin
- REU Site in Raptor Research, Raptor Research Center and Department of Biological Sciences, Boise State University, Boise, ID, U.S.A
- Biology Department, William and Mary, Williamsburg, VA, U.S.A
| | - Kara A Navock
- REU Site in Raptor Research, Raptor Research Center and Department of Biological Sciences, Boise State University, Boise, ID, U.S.A
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Jelinek HF, Mousa M, Alefishat E, Osman W, Spence I, Bu D, Feng SF, Byrd J, Magni PA, Sahibzada S, Tay GK, Alsafar HS. Evolution, Ecology, and Zoonotic Transmission of Betacoronaviruses: A Review. Front Vet Sci 2021; 8:644414. [PMID: 34095271 PMCID: PMC8173069 DOI: 10.3389/fvets.2021.644414] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/25/2021] [Indexed: 12/18/2022] Open
Abstract
Coronavirus infections have been a part of the animal kingdom for millennia. The difference emerging in the twenty-first century is that a greater number of novel coronaviruses are being discovered primarily due to more advanced technology and that a greater number can be transmitted to humans, either directly or via an intermediate host. This has a range of effects from annual infections that are mild to full-blown pandemics. This review compares the zoonotic potential and relationship between MERS, SARS-CoV, and SARS-CoV-2. The role of bats as possible host species and possible intermediate hosts including pangolins, civets, mink, birds, and other mammals are discussed with reference to mutations of the viral genome affecting zoonosis. Ecological, social, cultural, and environmental factors that may play a role in zoonotic transmission are considered with reference to SARS-CoV, MERS, and SARS-CoV-2 and possible future zoonotic events.
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Affiliation(s)
- Herbert F. Jelinek
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Biomedical Engineering, College of Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center of Heath Engineering Innovation, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Mira Mousa
- Nuffield Department of Women's and Reproduction Health, Oxford University, Oxford, United Kingdom
| | - Eman Alefishat
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Pharmacology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, The University of Jordan, Amman, Jordan
| | - Wael Osman
- Department of Chemistry, College of Arts and Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Ian Spence
- Discipline of Pharmacology, University of Sydney, Sydney, NSW, Australia
| | - Dengpan Bu
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Science, Beijing, China
| | - Samuel F. Feng
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Mathematics, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Jason Byrd
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Paola A. Magni
- Discipline of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, WA, Australia
- Murdoch University Singapore, King's Centre, Singapore, Singapore
| | - Shafi Sahibzada
- Antimicrobial Resistance and Infectious Diseases Laboratory, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA, Australia
| | - Guan K. Tay
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Division of Psychiatry, Faculty of Health and Medical Sciences, The University of Western Australia, Crawley, WA, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Habiba S. Alsafar
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Biomedical Engineering, College of Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Genetics and Molecular Biology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
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Overview of Bat and Wildlife Coronavirus Surveillance in Africa: A Framework for Global Investigations. Viruses 2021; 13:v13050936. [PMID: 34070175 PMCID: PMC8158508 DOI: 10.3390/v13050936] [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: 04/06/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 01/13/2023] Open
Abstract
The ongoing coronavirus disease 2019 (COVID-19) pandemic has had devastating health and socio-economic impacts. Human activities, especially at the wildlife interphase, are at the core of forces driving the emergence of new viral agents. Global surveillance activities have identified bats as the natural hosts of diverse coronaviruses, with other domestic and wildlife animal species possibly acting as intermediate or spillover hosts. The African continent is confronted by several factors that challenge prevention and response to novel disease emergences, such as high species diversity, inadequate health systems, and drastic social and ecosystem changes. We reviewed published animal coronavirus surveillance studies conducted in Africa, specifically summarizing surveillance approaches, species numbers tested, and findings. Far more surveillance has been initiated among bat populations than other wildlife and domestic animals, with nearly 26,000 bat individuals tested. Though coronaviruses have been identified from approximately 7% of the total bats tested, surveillance among other animals identified coronaviruses in less than 1%. In addition to a large undescribed diversity, sequences related to four of the seven human coronaviruses have been reported from African bats. The review highlights research gaps and the disparity in surveillance efforts between different animal groups (particularly potential spillover hosts) and concludes with proposed strategies for improved future biosurveillance.
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Colman RE, Brinkerhoff RJ, Busch JD, Ray C, Doyle A, Sahl JW, Keim P, Collinge SK, Wagner DM. No evidence for enzootic plague within black-tailed prairie dog (Cynomys ludovicianus) populations. Integr Zool 2021; 16:834-851. [PMID: 33882192 PMCID: PMC9292313 DOI: 10.1111/1749-4877.12546] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Yersinia pestis, causative agent of plague, occurs throughout the western United States in rodent populations and periodically causes epizootics in susceptible species, including black‐tailed prairie dogs (Cynomys ludovicianus). How Y. pestis persists long‐term in the environment between these epizootics is poorly understood but multiple mechanisms have been proposed, including, among others, a separate enzootic transmission cycle that maintains Y. pestis without involvement of epizootic hosts and persistence of Y. pestis within epizootic host populations without causing high mortality within those populations. We live‐trapped and collected fleas from black‐tailed prairie dogs and other mammal species from sites with and without black‐tailed prairie dogs in 2004 and 2005 and tested all fleas for presence of Y. pestis. Y. pestis was not detected in 2126 fleas collected in 2004 but was detected in 294 fleas collected from multiple sites in 2005, before and during a widespread epizootic that drastically reduced black‐tailed prairie dog populations in the affected colonies. Temporal and spatial patterns of Y. pestis occurrence in fleas and genotyping of Y. pestis present in some infected fleas suggest Y. pestis was introduced multiple times from sources outside the study area and once introduced, was dispersed between several sites. We conclude Y. pestis likely was not present in these black‐tailed prairie dog colonies prior to epizootic activity in these colonies. Although we did not identify likely enzootic hosts, we found evidence that deer mice (Peromyscus maniculatus) may serve as bridging hosts for Y. pestis between unknown enzootic hosts and black‐tailed prairie dogs.
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Affiliation(s)
- Rebecca E Colman
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - R Jory Brinkerhoff
- Environmental Studies Program, University of Colorado at Boulder, Boulder, Colorado, USA
| | - Joseph D Busch
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Chris Ray
- Environmental Studies Program, University of Colorado at Boulder, Boulder, Colorado, USA
| | - Adina Doyle
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Jason W Sahl
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Paul Keim
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Sharon K Collinge
- Environmental Studies Program, University of Colorado at Boulder, Boulder, Colorado, USA
| | - David M Wagner
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
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10
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Thoroughgood JT, Armstrong JS, White B, Anstead CA, Galloway TD, Lindsay LR, Shury TK, Lane JE, Chilton NB. Molecular Differentiation of Four Species of Oropsylla (Siphonaptera: Ceratophyllidae) Using PCR-Based Single Strand Conformation Polymorphism Analyses and DNA Sequencing. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:241-245. [PMID: 33432353 DOI: 10.1093/jme/tjaa161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Indexed: 06/12/2023]
Abstract
It is often difficult to distinguish morphologically between closely related species of fleas (Siphonaptera). Morphological identification of fleas often requires microscopic examination of internal structures in specimens cleared using caustic solutions. This process degrades DNA and/or inhibits DNA extraction from specimens, which limits molecular-based studies on individual fleas and their microbiomes. Our objective was to distinguish between Oropsylla rupestris (Jordan), Oropsylla tuberculata (Baker), Oropsylla bruneri (Baker), and Oropsylla labis (Jordan & Rothschild) (Ceratophyllidae) using PCR-based single strand conformation polymorphism (SSCP) analyses and DNA sequencing. A 446 bp region of the nuclear 28S ribosomal RNA (rRNA) gene was used as the genetic marker. The results obtained for 36 reference specimens (i.e., fleas that were morphologically identified to species) revealed no intraspecific variation in DNA sequence, whereas the DNA sequences of the four species of Oropsylla differed from one another at two to six nucleotide positions. Each flea species also had a unique SSCP banding pattern. SSCP analyses were then used to identify another 84 fleas that had not been identified morphologically. DNA sequencing data confirmed the species identity of fleas subjected to SSCP. This demonstrates that PCR-SSCP combined with DNA sequencing of the 28S rRNA gene is a very effective approach for the delineation of four closely related species of flea.
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Affiliation(s)
| | - James S Armstrong
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Brandon White
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Clare A Anstead
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Terry D Galloway
- Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - L Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada R3T 2R2
| | - Todd K Shury
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada R3T 2R2
- Parks Canada Agency, Department of Veterinary Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4
| | - Jeffery E Lane
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Neil B Chilton
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Keuler KM, Bron GM, Griebel R, Richgels KLD. An invasive disease, sylvatic plague, increases fragmentation of black-tailed prairie dog (Cynomys ludovicianus) colonies. PLoS One 2020; 15:e0235907. [PMID: 32701990 PMCID: PMC7377483 DOI: 10.1371/journal.pone.0235907] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 06/24/2020] [Indexed: 12/03/2022] Open
Abstract
Context A disease can be a source of disturbance, causing population declines or extirpations, altering species interactions, and affecting habitat structure. This is particularly relevant for diseases that affect keystone species or ecosystem engineers, leading to potentially cascading effects on ecosystems. Objective We investigated the invasion of a non-native disease, plague, to a keystone species, prairie dogs, and documented the resulting extent of fragmentation and habitat loss in western grasslands. Specifically, we assessed how the arrival of plague in the Conata Basin, South Dakota, United States, affected the size, shape, and aggregation of prairie dog colonies, an animal species known to be highly susceptible to plague. Methods Colonies in the prairie dog complex were mapped every 1 to 3 years from 1993 to 2015. Plague was first confirmed in 2008 and we compared prairie dog complex and colony characteristics before and after the arrival of plague. Results As expected the colony complex and the patches in colonies became smaller and more fragmented after the arrival of plague; the total area of each colony and the mean area per patch within a colony decreased, the number of patches per colony increased, and mean contiguity of each patch decreased, leading to habitat fragmentation. Conclusion We demonstrate how an emerging infectious disease can act as a source of disturbance to natural systems and lead to potentially permanent alteration of habitat characteristics. While perhaps not traditionally thought of as a source of ecosystem disturbances, in recent years emerging infectious diseases have shown to be able to have large effects on ecosystems if they affect keystone species.
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Affiliation(s)
- Krystal M. Keuler
- National Wildlife Health Center, U. S. Geological Survey, Madison, WI, United States of America
| | - Gebbiena M. Bron
- National Wildlife Health Center, U. S. Geological Survey, Madison, WI, United States of America
| | - Randall Griebel
- U. S. Forest Service, Bridger-Teton National Forest, Jackson, WY, United States of America
| | - Katherine L. D. Richgels
- National Wildlife Health Center, U. S. Geological Survey, Madison, WI, United States of America
- * E-mail:
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12
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Ditmer MA, McGraw AM, Cornicelli L, Forester JD, Mahoney PJ, Moen RA, Stapleton SP, St-Louis V, VanderWaal K, Carstensen M. Using movement ecology to investigate meningeal worm risk in moose, Alces alces. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Anthropogenic habitat change and moderating climatic conditions have enabled the northward geographic expansion of white-tailed deer, Odocoileus virginianus, and of the parasitic nematode (meningeal worm) it carries, Parelaphostrongylus tenuis. This expansion can have consequences in dead-end host species for other ungulates because meningeal worm reduces health, causes morbidity or direct mortality, and has been attributed to population declines. In northeastern Minnesota, which marks the southern extent of the bioclimatic range for moose (Alces alces), the moose population has declined more than 50% in the last decade, with studies detecting P. tenuis in 25–45% of necropsied animals. We assessed the factors that most commonly are associated with meningeal worm infection by linking moose movement ecology with known P. tenuis infection status from necropsy. We outfitted moose with GPS collars to assess their space use and cause-specific mortality. Upon death of the subject animal, we performed a necropsy to determine the cause of death and document meningeal worm infection. We then created statistical models to assess the relationship between meningeal worm infection and exposure to hypothesized factors of infection risk based on the space use of each moose by season. Predictors included land cover types, deer space use and density, environmental conditions, and demographics of individual moose (age and sex). Moose with autumn home ranges that included more upland shrub/conifer, and individuals with high proportions of wet environments, regardless of season, had increased infection risk. In contrast, the strongest relationships we found showed that high proportions of mixed and conifer forest within spring home ranges resulted in reduced risk of infection. The spring models showed the strongest relationships between exposure and infection, potentially due to moose foraging on ground vegetation during spring. By incorporating movement of moose into disease ecology, we were able to take a top-down approach to test hypothesized components of infection risk with actual spatial and temporal exposure of individual necropsied moose. The probability of infection for moose was not influenced by deer density, although deer densities did not vary greatly within the study area (2–4 deer/km2), highlighting the importance of also considering both moose space use and environmental conditions in understanding infection risk. We suggest management strategies that use a combination of deer and land management prescriptions designed to limit contact rates in susceptible populations.
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Affiliation(s)
- Mark A Ditmer
- Conservation Department, Minnesota Zoo, Apple Valley, MN, USA
- Department of Fisheries, Wildlife & Conservation Biology, University of Minnesota, St. Paul, MN, USA
| | - Amanda M McGraw
- Natural Resources Research Institute and Department of Biology, University of Minnesota, Duluth, MN, USA
| | - Louis Cornicelli
- Wildlife Research Unit, Minnesota Department of Natural Resources, St. Paul, MN, USA
| | - James D Forester
- Department of Fisheries, Wildlife & Conservation Biology, University of Minnesota, St. Paul, MN, USA
| | - Peter J Mahoney
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, USA
| | - Ron A Moen
- Natural Resources Research Institute and Department of Biology, University of Minnesota, Duluth, MN, USA
| | - Seth P Stapleton
- Conservation Department, Minnesota Zoo, Apple Valley, MN, USA
- Department of Fisheries, Wildlife & Conservation Biology, University of Minnesota, St. Paul, MN, USA
| | - Véronique St-Louis
- Wildlife Research Unit, Minnesota Department of Natural Resources, Forest Lake, MN, USA
| | - Kimberly VanderWaal
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Michelle Carstensen
- Wildlife Research Unit, Minnesota Department of Natural Resources, Forest Lake, MN, USA
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FLEA PARASITISM AND HOST SURVIVAL IN A PLAGUE-RELEVANT SYSTEM: THEORETICAL AND CONSERVATION IMPLICATIONS. J Wildl Dis 2019; 56:378-387. [PMID: 31880988 DOI: 10.7589/2019-08-201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Plague is a bacterial zoonosis of mammalian hosts and flea vectors. The disease is capable of ravaging rodent populations and transforming ecosystems. Because plague mortality is likely to be predicted by flea parasitism, it is critical to understand vector dynamics. It has been hypothesized that paltry precipitation and reduced vegetative production predispose herbivorous rodents to malnourishment and flea parasitism, and flea parasitism varies directly with plague mortality. We evaluated these hypotheses on five colonies of Utah prairie dogs (UPDs; Cynomys parvidens), on the Awapa Plateau, Utah, US, in 2013-16. Ten flea species were identified among 3,257 fleas from UPDs. These 10 flea species parasitize prairie dogs, mice, rats, voles, ground squirrels, chipmunks, and marmots, all known hosts of plague. The abundance of fleas on individual UPDs (1,198 observations) varied inversely with UPD body condition; fleas were most abundant on lightweight, malnourished UPDs. Flea abundance on UPDs was highest in dry years that were preceded by wet years. Increased precipitation and soil moisture in the prior year might generate humid microclimates in UPD burrows (that could facilitate flea survival and reproduction) and paltry precipitation in the current year could predispose UPDs to malnourishment and flea parasitism. Annual re-encounter rates for UPDs (1,072 observations) were reduced in wetter years preceded by drier years; reduced precipitation and vegetative production might kill UPDs, and increased flea densities in drier years could provide conditions for plague transmission (and UPD mortality) when moisture returns. Re-encounter rates were reduced for UPDs carrying at least one flea compared to UPDs with no detected fleas. These results support the hypothesis that reduced precipitation in the current year predisposes UPDs to flea parasitism. Our results also suggest a link between flea parasitism and UPD mortality. Given documented connections between flea parasitism and plague transmission, our results point toward an effect of flea parasitism on plague-related deaths for individual UPDs, a phenomenon rarely investigated in nature.
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Russell RE, Tripp DW, Rocke TE. Differential plague susceptibility in species and populations of prairie dogs. Ecol Evol 2019; 9:11962-11971. [PMID: 31695901 PMCID: PMC6822031 DOI: 10.1002/ece3.5684] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 08/28/2019] [Accepted: 09/02/2019] [Indexed: 11/24/2022] Open
Abstract
Laboratory trials conducted over the past decade at U.S. Geological Survey National Wildlife Health Center indicate that wild populations of prairie dogs (Cynomys spp.) display different degrees of susceptibility to experimental challenge with fully virulent Yersinia pestis, the causative agent of plague. We evaluated patterns in prairie dog susceptibility to plague to determine whether the historical occurrence of plague at location of capture was related to survival times of prairie dogs challenged with Y. pestis. We found that black-tailed prairie dogs (Cynomys ludovicianus) from South Dakota (captured prior to the detection of plague in the state), Gunnison's prairie dogs (Cynomys gunnisoni) from Colorado, and Utah prairie dogs (Cynomys parvidens) from Utah were most susceptible to plague. Though the susceptibility of black-tailed prairie dogs in South Dakota compared with western locations supports our hypothesis regarding historical exposure, both Colorado and Utah prairie dogs have a long history of exposure to plague. It is possible that for these populations, genetic isolation/bottle necks have made them more susceptible to plague outbreaks.
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Affiliation(s)
- Robin E. Russell
- National Wildlife Health CenterU.S. Geological SurveyMadisonWIUSA
| | - Daniel W. Tripp
- Wildlife Health ProgramColorado Parks and WildlifeFort CollinsCOUSA
| | - Tonie E. Rocke
- National Wildlife Health CenterU.S. Geological SurveyMadisonWIUSA
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15
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Zhu S, Zimmerman D, Deem SL. A Review of Zoonotic Pathogens of Dromedary Camels. ECOHEALTH 2019; 16:356-377. [PMID: 31140075 PMCID: PMC7087575 DOI: 10.1007/s10393-019-01413-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 06/09/2023]
Abstract
Dromedary, or one-humped, camels Camelus dromedarius are an almost exclusively domesticated species that are common in arid areas as both beasts of burden and production animals for meat and milk. Currently, there are approximately 30 million dromedary camels, with highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability for camels to act as a point source or vector for disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and a growth in the interface with wildlife as camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that the majority of publications (65%) focused on Middle East respiratory syndrome (MERS), brucellosis, Echinococcus granulosus, and Rift Valley fever. The high fatality from MERS outbreaks during 2012-2016 elicited an immediate response from the research community as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Yersinia pestis, Coxiella burnetii, and Crimean-Congo hemorrhagic fever are just as important to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. In this review, we provide an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events.
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Affiliation(s)
- Sophie Zhu
- Graduate Group in Epidemiology, University of California, Davis, CA, 95616, USA.
| | - Dawn Zimmerman
- Global Health Program, Smithsonian Conservation Biology Institute, Washington, DC, 20008, USA
| | - Sharon L Deem
- Institute for Conservation Medicine, Saint Louis Zoo, Saint Louis, MO, 63110, USA
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16
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Bron GM, Malavé CM, Boulerice JT, Osorio JE, Rocke TE. Plague-Positive Mouse Fleas on Mice Before Plague Induced Die-Offs in Black-Tailed and White-Tailed Prairie Dogs. Vector Borne Zoonotic Dis 2019; 19:486-493. [PMID: 30994405 DOI: 10.1089/vbz.2018.2322] [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] [Indexed: 11/12/2022] Open
Abstract
Plague is a lethal zoonotic disease associated with rodents worldwide. In the western United States, plague outbreaks can decimate prairie dog (Cynomys spp.) colonies. However, it is unclear where the causative agent, Yersinia pestis, of this flea-borne disease is maintained between outbreaks, and what triggers plague-induced prairie dog die-offs. Less susceptible rodent hosts, such as mice, could serve to maintain the bacterium, transport infectious fleas across a colony, or introduce the pathogen to other colonies, possibly facilitating an outbreak. Here, we assess the potential role of two short-lived rodent species, North American deer mice (Peromyscus maniculatus) and Northern grasshopper mice (Onychomys leucogaster) in plague dynamics on prairie dog colonies. We live-trapped short-lived rodents and collected their fleas on black-tailed (Cynomys ludovicianus, Montana and South Dakota), white-tailed (Cynomys leucurus, Utah and Wyoming), and Utah prairie dog colonies (Cynomys parvidens, Utah) annually, from 2013 to 2016. Plague outbreaks occurred on colonies of all three species. In all study areas, deer mouse abundance was high the year before plague-induced prairie dog die-offs, but mouse abundance per colony was not predictive of plague die-offs in prairie dogs. We did not detect Y. pestis DNA in mouse fleas during prairie dog die-offs, but in three cases we found it beforehand. On one white-tailed prairie dog colony, we detected Y. pestis positive fleas on one grasshopper mouse and several prairie dogs live-trapped 10 days later, months before visible declines and plague-confirmed mortality of prairie dogs. On one black-tailed prairie dog colony, we detected Y. pestis positive fleas on two deer mice 3 months before evidence of plague was detected in prairie dogs or their fleas and also well before a plague-induced die-off. These observations of plague positive fleas on mice could represent early spillover events of Y. pestis from prairie dogs or an unknown reservoir, or possible movement of infectious fleas by mice.
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Affiliation(s)
- Gebbiena M Bron
- 1 U.S. Geological Survey National Wildlife Health Center, Madison, Wisconsin.,2 Department of Pathobiological Sciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, Wisconsin
| | - Carly M Malavé
- 1 U.S. Geological Survey National Wildlife Health Center, Madison, Wisconsin
| | | | - Jorge E Osorio
- 2 Department of Pathobiological Sciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, Wisconsin
| | - Tonie E Rocke
- 1 U.S. Geological Survey National Wildlife Health Center, Madison, Wisconsin
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17
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Maestas LP, Britten HB. Effects of Deltamethrin Treatment on Small Mammal and Ectoparasite Population Dynamics and Plague Prevalence in a North American Mixed-Grass Prairie System. Vector Borne Zoonotic Dis 2019; 19:274-283. [DOI: 10.1089/vbz.2018.2332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lauren P. Maestas
- Department of Biology, University of South Dakota, Vermillion, South Dakota
| | - Hugh B. Britten
- Department of Biology, University of South Dakota, Vermillion, South Dakota
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18
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Biggins DE, Eads DA. Prairie Dogs, Persistent Plague, Flocking Fleas, and Pernicious Positive Feedback. Front Vet Sci 2019; 6:75. [PMID: 30984769 PMCID: PMC6447679 DOI: 10.3389/fvets.2019.00075] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 02/21/2019] [Indexed: 01/21/2023] Open
Abstract
Plague (caused by the bacterium Yersinia pestis) is a deadly flea-borne disease that remains a threat to public health nearly worldwide and is particularly disruptive ecologically where it has been introduced. We review hypotheses regarding maintenance and transmission of Y. pestis, emphasizing recent data from North America supporting maintenance by persistent transmission that results in sustained non-epizootic (but variable) rates of mortality in hosts. This maintenance mechanism may facilitate periodic epizootic eruptions "in place" because the need for repeated reinvasion from disjunct sources is eliminated. Resulting explosive outbreaks that spread rapidly in time and space are likely enhanced by synergistic positive feedback (PFB) cycles involving flea vectors, hosts, and the plague bacterium itself. Although PFB has been implied in plague literature for at least 50 years, we propose this mechanism, particularly with regard to flea responses, as central to epizootic plague rather than a phenomenon worthy of just peripheral mention. We also present new data on increases in flea:host ratios resulting from recreational shooting and poisoning as possible triggers for the transition from enzootic maintenance to PFB cycles and epizootic explosions. Although plague outbreaks have received much historic attention, PFB cycles that result in decimation of host populations lead to speculation that epizootic eruptions might not be part of the adaptive evolutionary strategy of Y. pestis but might instead be a tolerated intermittent cost of its modus operandi. We also speculate that there may be mammal communities where epizootics, as we define them, are rare or absent. Absence of plague epizootics might translate into reduced public health risk but does not necessarily equate to inconsequential ecologic impact.
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Affiliation(s)
- Dean E. Biggins
- United States Geological Survey, Fort Collins Science Center, Fort Collins, CO, United States
| | - David A. Eads
- United States Geological Survey, Fort Collins Science Center, Fort Collins, CO, United States
- Department of Biology, Colorado State University, Fort Collins, CO, United States
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19
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Eads DA, Biggins DE, Bowser J, McAllister JC, Griebel RL, Childers E, Livieri TM, Painter C, Krank LS, Bly K. RESISTANCE TO DELTAMETHRIN IN PRAIRIE DOG ( CYNOMYS LUDOVICIANUS) FLEAS IN THE FIELD AND IN THE LABORATORY. J Wildl Dis 2018; 54:745-754. [PMID: 29723100 PMCID: PMC6710209 DOI: 10.7589/2017-10-250] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sylvatic plague poses a substantial risk to black-tailed prairie dogs ( Cynomys ludovicianus) and their obligate predator, the black-footed ferret ( Mustela nigripes). The effects of plague on prairie dogs and ferrets are mitigated using a deltamethrin pulicide dust that reduces the spread of plague by killing fleas, the vector for the plague bacterium. In portions of Conata Basin, Buffalo Gap National Grassland, and Badlands National Park, South Dakota, US, 0.05% deltamethrin has been infused into prairie dog burrows on an annual basis since 2005. We aimed to determine if fleas ( Oropsylla hirsuta) in portions of the Conata Basin and Badlands National Park have evolved resistance to deltamethrin. We assessed flea prevalence, obtained by combing prairie dogs for fleas, as an indirect measure of resistance. Dusting was ineffective in two colonies treated with deltamethrin for >8 yr; flea prevalence rebounded within 1 mo of dusting. We used a bioassay that exposed fleas to deltamethrin to directly evaluate resistance. Fleas from colonies with >8 yr of exposure to deltamethrin exhibited survival rates that were 15% to 83% higher than fleas from sites that had never been dusted. All fleas were paralyzed or dead after 55 min. After removal from deltamethrin, 30% of fleas from the dusted colonies recovered, compared with 1% of fleas from the not-dusted sites. Thus, deltamethrin paralyzed fleas from colonies with long-term exposure to deltamethrin, but a substantial number of those fleas was resistant and recovered. Flea collections from live-trapped prairie dogs in Thunder Basin National Grassland, Wyoming, US, suggest that, in some cases, fleas might begin to develop a moderate level of resistance to deltamethrin after 5-6 yr of annual treatments. Restoration of black-footed ferrets and prairie dogs will rely on an adaptive, integrative approach to plague management, for instance involving the use of vaccines and rotating applications of insecticidal products with different active ingredients.
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Affiliation(s)
- David A. Eads
- Department of Biology, Colorado State University, Campus Delivery 1878, Fort Collins, Colorado 80523, USA
- Corresponding author ()
| | - Dean E. Biggins
- US Geological Survey, Fort Collins Science Center, 2150 Centre Avenue Building C, Fort Collins, Colorado 80526, USA
| | - Jonathan Bowser
- US Geological Survey, Fort Collins Science Center, 2150 Centre Avenue Building C, Fort Collins, Colorado 80526, USA
| | - Janet C. McAllister
- Centers for Disease Control and Prevention, Fort Collins, Colorado 80521, USA
| | - Randall L. Griebel
- US Forest Service, Wall Ranger District, 710 Main Street, Wall, South Dakota 57790, USA
| | - Eddie Childers
- National Park Service, Badlands National Park, 25216 Ben Reifel Road, Interior, South Dakota 57750, USA
| | - Travis M. Livieri
- Prairie Wildlife Research, PO Box 308, Wellington, Colorado 80549, USA
| | - Cristi Painter
- US Forest Service, Thunder Basin National Grassland, 2250 E Richards Street, Douglas, Wyoming 82633, USA
| | - Lindsey Sterling Krank
- The Humane Society of the United States, Prairie Dog Coalition, 2525 Arapahoe #E4-527, Boulder, Colorado 80302, USA
| | - Kristy Bly
- World Wildlife Fund, Northern Great Plains Program, 458 Saddle Ridge Road, Hamilton, Montana 59840, USA
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20
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Danforth M, Tucker J, Novak M. The Deer Mouse (Peromyscus maniculatus) as an Enzootic Reservoir of Plague in California. ECOHEALTH 2018; 15:566-576. [PMID: 29700709 DOI: 10.1007/s10393-018-1337-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 05/17/2023]
Abstract
It has long been theorized that deer mice (Peromyscus maniculatus) are a primary reservoir of Yersinia pestis in California. However, recent research from other parts of the western USA has implicated deer mice as spillover hosts during epizootic plague transmission. This retrospective study analyzed deer mouse data collected for plague surveillance by public health agencies in California from 1971 to 2016 to help elucidate the role of deer mice in plague transmission. The fleas most commonly found on deer mice were poor vectors of Y. pestis and occurred in insufficient numbers to maintain transmission of the pathogen, while fleas whose natural hosts are deer mice were rarely observed and even more rarely found infected with Y. pestis on other rodent hosts. Seroprevalence of Y. pestis antibodies in deer mice was significantly lower than that of several chipmunk and squirrel species. These analyses suggest that it is unlikely that deer mice play an important role in maintaining plague transmission in California. While they may not be primary reservoirs, results supported the premise that deer mice are occasionally exposed to and infected by Y. pestis and instead may be spillover hosts.
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Affiliation(s)
- Mary Danforth
- California Department of Public Health, Vector-Borne Disease Section, 8633 Bond Rd, Elk Grove, CA, 95624, USA.
| | - James Tucker
- California Department of Public Health, Vector-Borne Disease Section, 8633 Bond Rd, Elk Grove, CA, 95624, USA
| | - Mark Novak
- California Department of Public Health, Vector-Borne Disease Section, 8633 Bond Rd, Elk Grove, CA, 95624, USA
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21
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D’Ortenzio E, Lemaître N, Brouat C, Loubet P, Sebbane F, Rajerison M, Baril L, Yazdanpanah Y. Plague: Bridging gaps towards better disease control. Med Mal Infect 2018; 48:307-317. [DOI: 10.1016/j.medmal.2018.04.393] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/13/2018] [Indexed: 01/14/2023]
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22
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Markman DW, Antolin MF, Bowen RA, Wheat WH, Woods M, Gonzalez-Juarrero M, Jackson M. Yersinia pestis Survival and Replication in Potential Ameba Reservoir. Emerg Infect Dis 2018; 24:294-302. [PMID: 29350155 PMCID: PMC5782900 DOI: 10.3201/eid2402.171065] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Plague ecology is characterized by sporadic epizootics, then periods of dormancy. Building evidence suggests environmentally ubiquitous amebae act as feral macrophages and hosts to many intracellular pathogens. We conducted environmental genetic surveys and laboratory co-culture infection experiments to assess whether plague bacteria were resistant to digestion by 5 environmental ameba species. First, we demonstrated that Yersinia pestis is resistant or transiently resistant to various ameba species. Second, we showed that Y. pestis survives and replicates intracellularly within Dictyostelium discoideum amebae for ˃48 hours postinfection, whereas control bacteria were destroyed in <1 hour. Finally, we found that Y. pestis resides within ameba structures synonymous with those found in infected human macrophages, for which Y. pestis is a competent pathogen. Evidence supporting amebae as potential plague reservoirs stresses the importance of recognizing pathogen-harboring amebae as threats to public health, agriculture, conservation, and biodefense.
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23
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Salkeld DJ. Vaccines for Conservation: Plague, Prairie Dogs & Black-Footed Ferrets as a Case Study. ECOHEALTH 2017; 14:432-437. [PMID: 28879613 DOI: 10.1007/s10393-017-1273-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 08/08/2017] [Indexed: 06/07/2023]
Abstract
The endangered black-footed ferret (Mustela nigripes) is affected by plague, caused by Yersinia pestis, both directly, as a cause of mortality, and indirectly, because of the impacts of plague on its prairie dog (Cynomys spp.) prey base. Recent developments in vaccines and vaccine delivery have raised the possibility of plague control in prairie dog populations, thereby protecting ferret populations. A large-scale experimental investigation across the western US shows that sylvatic plague vaccine delivered in oral baits can increase prairie dog survival. In northern Colorado, an examination of the efficacy of insecticides to control fleas and plague vaccine shows that timing and method of plague control is important, with different implications for long-term and large-scale management of Y. pestis delivery. In both cases, the studies show that ambitious field-work and cross-sectoral collaboration can provide potential solutions to difficult issues of wildlife management, conservation and disease ecology.
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Affiliation(s)
- Daniel J Salkeld
- Department of Biology, Colorado State University, Fort Collins, CO, USA.
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24
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Tripp DW, Rocke TE, Runge JP, Abbott RC, Miller MW. Burrow Dusting or Oral Vaccination Prevents Plague-Associated Prairie Dog Colony Collapse. ECOHEALTH 2017; 14:451-462. [PMID: 28643090 PMCID: PMC5662691 DOI: 10.1007/s10393-017-1236-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/15/2017] [Accepted: 03/20/2017] [Indexed: 05/24/2023]
Abstract
Plague impacts prairie dogs (Cynomys spp.), the endangered black-footed ferret (Mustela nigripes) and other sensitive wildlife species. We compared efficacy of prophylactic treatments (burrow dusting with deltamethrin or oral vaccination with recombinant "sylvatic plague vaccine" [RCN-F1/V307]) to placebo treatment in black-tailed prairie dog (C. ludovicianus) colonies. Between 2013 and 2015, we measured prairie dog apparent survival, burrow activity and flea abundance on triplicate plots ("blocks") receiving dust, vaccine or placebo treatment. Epizootic plague affected all three blocks but emerged asynchronously. Dust plots had fewer fleas per burrow (P < 0.0001), and prairie dogs captured on dust plots had fewer fleas (P < 0.0001) than those on vaccine or placebo plots. Burrow activity and prairie dog density declined sharply in placebo plots when epizootic plague emerged. Patterns in corresponding dust and vaccine plots were less consistent and appeared strongly influenced by timing of treatment applications relative to plague emergence. Deltamethrin or oral vaccination enhanced apparent survival within two blocks. Applying insecticide or vaccine prior to epizootic emergence blunted effects of plague on prairie dog survival and abundance, thereby preventing colony collapse. Successful plague mitigation will likely entail strategic combined uses of burrow dusting and oral vaccination within large colonies or colony complexes.
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Affiliation(s)
- Daniel W Tripp
- Colorado Division of Parks and Wildlife, Wildlife Health Program, 4330 Laporte Avenue, Fort Collins, CO, 80521-2153, USA.
| | - Tonie E Rocke
- United States Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI, 53711, USA
| | - Jonathan P Runge
- Colorado Division of Parks and Wildlife, Terrestrial Resources Program, 317 West Prospect Road, Fort Collins, CO, 80526-2097, USA
| | - Rachel C Abbott
- United States Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI, 53711, USA
| | - Michael W Miller
- Colorado Division of Parks and Wildlife, Wildlife Health Program, 4330 Laporte Avenue, Fort Collins, CO, 80521-2153, USA
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25
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Eads DA, Biggins DE. Paltry past-precipitation: Predisposing prairie dogs to plague? J Wildl Manage 2017. [DOI: 10.1002/jwmg.21281] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- David A. Eads
- Department of Biology, Colorado State University; U.S. Geological Survey, Fort Collins Science Center; 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
| | - Dean E. Biggins
- U.S. Geological Survey; Fort Collins Science Center; 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
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26
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Maestas LP, Britten HB. Flea and Small Mammal Species Composition in Mixed-Grass Prairies: Implications for the Maintenance ofYersinia pestis. Vector Borne Zoonotic Dis 2017; 17:467-474. [DOI: 10.1089/vbz.2016.2069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Lauren P. Maestas
- Department of Biology, University of South Dakota, Vermillion, South Dakota
| | - Hugh B. Britten
- Department of Biology, University of South Dakota, Vermillion, South Dakota
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27
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Eads DA, Hoogland JL. Precipitation, Climate Change, and Parasitism of Prairie Dogs by Fleas that Transmit Plague. J Parasitol 2017; 103:309-319. [PMID: 28359175 DOI: 10.1645/16-195] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Fleas (Insecta: Siphonaptera) are hematophagous ectoparasites that can reduce the fitness of vertebrate hosts. Laboratory populations of fleas decline under dry conditions, implying that populations of fleas will also decline when precipitation is scarce under natural conditions. If precipitation and hence vegetative production are reduced, however, then herbivorous hosts might suffer declines in body condition and have weakened defenses against fleas, so that fleas will increase in abundance. We tested these competing hypotheses using information from 23 yr of research on 3 species of colonial prairie dogs in the western United States: Gunnison's prairie dog (Cynomys gunnisoni, 1989-1994), Utah prairie dog (Cynomys parvidens, 1996-2005), and white-tailed prairie dog (Cynomys leucurus, 2006-2012). For all 3 species, flea-counts per individual varied inversely with the number of days in the prior growing season with >10 mm of precipitation, an index of the number of precipitation events that might have caused a substantial, prolonged increase in soil moisture and vegetative production. Flea-counts per Utah prairie dog also varied inversely with cumulative precipitation of the prior growing season. Furthermore, flea-counts per Gunnison's and white-tailed prairie dog varied inversely with cumulative precipitation of the just-completed January and February. These results complement research on black-tailed prairie dog (Cynomys ludovicianus) and might have important ramifications for plague, a bacterial disease transmitted by fleas that devastates populations of prairie dogs. In particular, our results might help to explain why, at some colonies, epizootics of plague, which can kill >95% of prairie dogs, are more likely to occur during or shortly after periods of reduced precipitation. Climate change is projected to increase the frequency of droughts in the grasslands of western North America. If so, then climate change might affect the occurrence of plague epizootics among prairie dogs and other mammalian species that associate with them.
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Affiliation(s)
- David A Eads
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523. Correspondence should be sent to David A. Eads at:
| | - John L Hoogland
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523. Correspondence should be sent to David A. Eads at:
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