1
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Donaldson JE, Ezenwa VO, Morrison TA, Holdo RM. Effects of migratory animals on resident parasite dynamics. Trends Ecol Evol 2024:S0169-5347(24)00019-3. [PMID: 38355367 DOI: 10.1016/j.tree.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 01/08/2024] [Accepted: 01/16/2024] [Indexed: 02/16/2024]
Abstract
Migratory animals can bring parasites into resident animal (i.e., non-migratory) home ranges (transport effects) and exert trophic effects that either promote or reduce parasite exposure to resident hosts. Here, we examine the importance of these transport and trophic effects and their interactions for resident parasite dynamics. We propose that migrant transport and trophic effects are impacted by the number of migratory animals entering a resident's home range (migration intensity), the amount of time that migrants spend within a resident's home range (migration duration), and the timing of migrant-resident interactions. We then incorporate migration intensity, duration, and timing into a framework for exploring the net impact of migrant trophic and transport effects on resident animal parasite prevalence.
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Affiliation(s)
| | - Vanessa O Ezenwa
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Thomas A Morrison
- School of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Ricardo M Holdo
- Odum School of Ecology, University of Georgia, Athens, GA, USA
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2
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Seguel M, Budischak SA, Jolles AE, Ezenwa VO. Helminth-associated changes in host immune phenotype connect top-down and bottom-up interactions during co-infection. Funct Ecol 2023; 37:860-872. [PMID: 37214767 PMCID: PMC10195069 DOI: 10.1111/1365-2435.14237] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 11/01/2022] [Indexed: 11/26/2022]
Abstract
1. Within-host parasite interactions can be mediated by the host and changes in host phenotypes often serve as indicators of the presence or intensity of parasite interactions. 2. Parasites like helminths induce a range of physiological, morphological, and immunological changes in hosts that can drive bottom-up (resource-mediated) or top-down (immune-mediated) interactions with co-infecting parasites. Although top-down and bottom-up interactions are typically studied in isolation, the diverse phenotypic changes induced by parasite infection may serve as a useful tool for understanding if, and when, these processes act in concert. 3. Using an anthelmintic treatment study of African buffalo (Syncerus caffer), we tracked changes in host immunological and morphological phenotypes during helminth-coccidia co-infection to investigate their role in driving independent and combinatorial bottom-up and top-down parasite interactions. We also examined repercussions for host fitness. 4. Clearance of a blood-sucking helminth, Haemonchus, from the host gastrointestinal tract induced a systemic Th2 immune phenotype, while clearance of a tissue-feeding helminth, Cooperia, induced a systemic Th1 phenotype. Furthermore, the Haemonchus-associated systemic Th2 immune phenotype drove simultaneous top-down and bottom-up effects that increased coccidia shedding by changing the immunological and morphological landscapes of the intestine. 5. Higher coccidia shedding was associated with lower host body condition, a lower chance of pregnancy, and older age at first pregnancy, suggesting that coccidia infection imposed significant condition and reproductive costs on the host. 6. Our findings suggest that top-down and bottom-up interactions may commonly co-occur and that tracking key host phenotypes that change in response to infection can help uncover complex pathways by which parasites interact.
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Affiliation(s)
- Mauricio Seguel
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Sarah A. Budischak
- W.M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, USA
| | - Anna E. Jolles
- Department of Biomedical Sciences and Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Vanessa O. Ezenwa
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
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3
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Warburton EM, Budischak SA, Jolles AE, Ezenwa VO. Within-host and external environments differentially shape β-diversity across parasite life stages. J Anim Ecol 2023; 92:665-676. [PMID: 36567629 DOI: 10.1111/1365-2656.13877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 12/09/2022] [Indexed: 12/27/2022]
Abstract
Uncovering drivers of community assembly is a key aspect of learning how biological communities function. Drivers of community similarity can be especially useful in this task as they affect assemblage-level changes that lead to differences in species diversity between habitats. Concepts of β-diversity originally developed for use in free-living communities have been widely applied to parasite communities to gain insight into how infection risk changes with local conditions by comparing parasite communities across abiotic and biotic gradients. Factors shaping β-diversity in communities of immature parasites, such as larvae, are largely unknown. This is a key knowledge gap as larvae are frequently the infective life-stage and understanding variation in these larval communities is thus key for disease prevention. Our goal was to uncover links between β-diversity of parasite communities at different life stages; therefore, we used gastrointestinal nematodes infecting African buffalo in Kruger National Park, South Africa, to investigate within-host and extra-host drivers of adult and larval parasite community similarity. We employed a cross-sectional approach using PERMANOVA that examined each worm community at a single time point to assess independent drivers of β-diversity in larvae and adults as well as a longitudinal approach with path analysis where adult and larval communities from the same host were compared to better link drivers of β-diversity between these two life stages. Using the cross-sectional approach, we generally found that intrinsic, within-host traits had significant effects on β-diversity of adult nematode communities, while extrinsic, extra-host variables had significant effects on β-diversity of larval nematode communities. However, the longitudinal approach provided evidence that intrinsic, within-host factors affected the larval community indirectly via the adult community. Our results provide key data for the comparison of community-level processes where adult and immature stages inhabit vastly different habitats (i.e. within-host vs. abiotic environment). In the context of parasitism, this helps elucidate host infection risk via larval stages and the drivers that shape persistence of adult parasite assemblages, both of which are useful for predicting and preventing infectious disease.
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Affiliation(s)
- Elizabeth M Warburton
- Center for the Ecology of Infectious Diseases, Odum School of Ecology, University of Georgia, Athens, Georgia, USA
| | - Sarah A Budischak
- W.M. Keck Department of Science, Claremont McKenna College, Claremont, California, USA
| | - Anna E Jolles
- College of Veterinary Medicine and Department of Integrative Biology, Oregon State University, Corvallis, Oregon, USA
| | - Vanessa O Ezenwa
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
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4
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Koltz AM, Civitello DJ, Becker DJ, Deem SL, Classen AT, Barton B, Brenn-White M, Johnson ZE, Kutz S, Malishev M, Preston DL, Vannatta JT, Penczykowski RM, Ezenwa VO. Sublethal effects of parasitism on ruminants can have cascading consequences for ecosystems. Proc Natl Acad Sci U S A 2022; 119:e2117381119. [PMID: 35533278 PMCID: PMC9171767 DOI: 10.1073/pnas.2117381119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/17/2022] [Indexed: 12/29/2022] Open
Abstract
Parasitic infections are common, but how they shape ecosystem-level processes is understudied. Using a mathematical model and meta-analysis, we explored the potential for helminth parasites to trigger trophic cascades through lethal and sublethal effects imposed on herbivorous ruminant hosts after infection. First, using the model, we linked negative effects of parasitic infection on host survival, fecundity, and feeding rate to host and producer biomass. Our model, parameterized with data from a well-documented producer–caribou–helminth system, reveals that even moderate impacts of parasites on host survival, fecundity, or feeding rate can have cascading effects on ruminant host and producer biomass. Second, using meta-analysis, we investigated the links between helminth infections and traits of free-living ruminant hosts in nature. We found that helminth infections tend to exert negative but sublethal effects on ruminant hosts. Specifically, infection significantly reduces host feeding rates, body mass, and body condition but has weak and highly variable effects on survival and fecundity. Together, these findings suggest that while helminth parasites can trigger trophic cascades through multiple mechanisms, overlooked sublethal effects on nonreproductive traits likely dominate their impacts on ecosystems. In particular, by reducing ruminant herbivory, pervasive helminth infections may contribute to a greener world.
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Affiliation(s)
- Amanda M. Koltz
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | | | | | - Sharon L. Deem
- Saint Louis Zoo Institute for Conservation Medicine, Saint Louis, MO 63110
| | - Aimée T. Classen
- Ecology and Evolutionary Biology Department, University of Michigan, Ann Arbor, MI 48109
| | - Brandon Barton
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Maris Brenn-White
- Saint Louis Zoo Institute for Conservation Medicine, Saint Louis, MO 63110
| | - Zoë E. Johnson
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762
| | - Susan Kutz
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | | | - Daniel L. Preston
- Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, CO 80523
| | - J. Trevor Vannatta
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | | | - Vanessa O. Ezenwa
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511
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5
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Richards RL, Drake JM, Ezenwa VO. Do predators keep prey healthy or make them sicker? A meta-analysis. Ecol Lett 2021; 25:278-294. [PMID: 34738700 DOI: 10.1111/ele.13919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/17/2021] [Accepted: 10/14/2021] [Indexed: 11/27/2022]
Abstract
Ecological theory suggests that predators can either keep prey populations healthy by reducing parasite burdens or alternatively, increase parasitism in prey. To quantify the overall magnitude and direction of the effect of predation on parasitism in prey observed in practice, we conducted a meta-analysis of 47 empirical studies. We also examined how study attributes, including parasite type and life cycle, habitat type, study design, and whether predators were able to directly consume prey contributed to variation in the predator-prey-parasite interaction. We found that the overall effect of predation on parasitism differed between parasites and parasitoids and that whether consumptive effects were present, and whether a predator was a non-host spreader of parasites, were the most important traits predicting the parasite response. Our results suggest that the mechanistic basis of predator-prey interactions strongly influences the effects of predators on parasites and that these effects, although context dependent, are predictable.
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Affiliation(s)
- Robert L Richards
- Odum School of Ecology, University of Georgia, Athens, Georgia, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - John M Drake
- Odum School of Ecology, University of Georgia, Athens, Georgia, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, Georgia, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, USA.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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6
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Ezenwa VO, Civitello DJ, Classen AT, Barton BT, Becker DJ, Brenn-White M, Deem SL, Kutz S, Malishev M, Penczykowski RM, Preston DL, Vannatta JT, Koltz AM. Response to Charlier et al.: Climate-Disease Feedbacks Mediated by Livestock Methane Emissions Are Plausible. Trends Ecol Evol 2021; 36:578-579. [PMID: 33966920 DOI: 10.1016/j.tree.2021.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 11/19/2022]
Affiliation(s)
- Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
| | | | - Aimée T Classen
- The Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Brandon T Barton
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | - Daniel J Becker
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Maris Brenn-White
- Institute for Conservation Medicine, Saint Louis Zoo, St. Louis, MO 63110, USA
| | - Sharon L Deem
- Institute for Conservation Medicine, Saint Louis Zoo, St. Louis, MO 63110, USA
| | - Susan Kutz
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | | | | | - Daniel L Preston
- Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - J Trevor Vannatta
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Amanda M Koltz
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
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7
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Sabey KA, Song SJ, Jolles A, Knight R, Ezenwa VO. Coinfection and infection duration shape how pathogens affect the African buffalo gut microbiota. ISME J 2021; 15:1359-1371. [PMID: 33328653 PMCID: PMC8115229 DOI: 10.1038/s41396-020-00855-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/10/2020] [Accepted: 11/20/2020] [Indexed: 01/07/2023]
Abstract
Changes in the gut microbiota during pathogen infection are often predicted to influence disease outcomes. However, studies exploring whether pathogens induce microbiota shifts have yielded inconsistent results. This suggests that variation in infection, rather than the presence of infection alone, might shape pathogen-microbiota relationships. For example, most hosts are coinfected with multiple pathogens simultaneously, and hosts vary in how long they are infected, which may amplify or diminish microbial shifts expected in response to a focal pathogen. We used a longitudinal anthelmintic treatment study of free-ranging African buffalo (Syncerus caffer) to examine whether (i) coinfection with bovine tuberculosis (Mycobacterium bovis, TB) and gastrointestinal nematodes, and (ii) the duration of TB infection, modified effects of single pathogens on the gut microbiota. By accounting for the interaction between TB and nematodes, we found that coinfection affected changes in microbial abundance associated with single infections. Furthermore, the duration of TB infection predicted more microbiota variation than the presence of TB. Importantly, coinfection and infection duration had nearly as much influence on microbial patterns as demographic and environmental factors commonly examined in microbiota research. These findings demonstrate that acknowledging infection heterogeneities may be crucial to understanding relationships between pathogens and the gut microbiota.
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Affiliation(s)
- Kate A Sabey
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Se Jin Song
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Center for Microbiome Innovation, University of California San Diego, La Jolla, CA, USA
| | - Anna Jolles
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR, USA
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Rob Knight
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Center for Microbiome Innovation, University of California San Diego, La Jolla, CA, USA
- Department of Computer Science and Engineering, University of California San Diego, La Jolla, CA, USA
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
- Odum School of Ecology, University of Georgia, Athens, GA, USA.
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8
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LaVere AA, Hamlin HJ, Lowers RH, Parrott BB, Ezenwa VO. Associations between testosterone and immune activity in alligators depend on bacteria species and temperature. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Russell H. Lowers
- Herndon Solutions Group, LLC, NASA Environmental and Medical Contract Kennedy Space Center FL USA
| | - Benjamin B. Parrott
- Odum School of Ecology University of Georgia Athens GA USA
- Savannah River Ecology Laboratory University of Georgia Aiken SC USA
| | - Vanessa O. Ezenwa
- Odum School of Ecology University of Georgia Athens GA USA
- Department of Infectious Diseases College of Veterinary Medicine University of Georgia Athens GA USA
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9
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Glidden CK, Coon CAC, Beechler BR, McNulty C, Ezenwa VO, Jolles AE. Co-infection best predicts respiratory viral infection in a wild host. J Anim Ecol 2021; 90:602-614. [PMID: 33232513 DOI: 10.1111/1365-2656.13391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/02/2020] [Indexed: 11/29/2022]
Abstract
The dynamics of directly transmitted pathogens in natural populations are likely to result from the combined effects of host traits, pathogen biology, and interactions among pathogens within a host. Discovering how these factors work in concert to shape variation in pathogen dynamics in natural host-multi-pathogen systems is fundamental to understanding population health. Here, we describe temporal variation in incidence and then elucidate the effect of hosts trait, season and pathogen co-occurrence on host infection risk using one of the most comprehensive studies of co-infection in a wild population: a suite of seven directly transmitted viral and bacterial respiratory infections from a 4-year study of 200 free-ranging African buffalo Syncerus caffer. Incidence of upper respiratory infections was common throughout the study-five out of the seven pathogens appeared to be consistently circulating throughout our study population. One pathogen exhibited clear outbreak dynamics in our final study year and another was rarely detected. Co-infection was also common in this system: The strongest indicator of pathogen occurrence for respiratory viruses was in fact the presence of other viral respiratory infections. Host traits had minimal effects on odds of pathogen occurrence but did modify pathogen-pathogen associations. In contrast, only season predicted bacterial pathogen occurrence. Though a combination of environmental, behavioural, and physiological factors work together to shape disease dynamics, we found pathogen associations best determined infection risk. Our study demonstrates that, in the absence of very fine-scale data, the intricate changes among these factors are best represented by co-infection.
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Affiliation(s)
- Caroline K Glidden
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Courtney A C Coon
- Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
| | - Brianna R Beechler
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - Chase McNulty
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Anna E Jolles
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.,College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
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10
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Tchouassi DP, Torto B, Sang R, Riginos C, Ezenwa VO. Large herbivore loss has complex effects on mosquito ecology and vector-borne disease risk. Transbound Emerg Dis 2020; 68:2503-2513. [PMID: 33170555 DOI: 10.1111/tbed.13918] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/25/2020] [Accepted: 11/06/2020] [Indexed: 12/15/2022]
Abstract
Loss of biodiversity can affect transmission of infectious diseases in at least two ways: by altering host and vector abundance or by influencing host and vector behaviour. We used a large herbivore exclusion experiment to investigate the effects of wildlife loss on the abundance and feeding behaviour of mosquito vectors and to explore consequences for vector-borne disease transmission. Large herbivore loss affected both mosquito abundance and blood-feeding behaviour. For Aedes mcintoshi, the dominant mosquito species in our study and a primary vector of Rift Valley fever virus (RVFV), abundance decreased with large herbivore loss, while blood feeding on humans increased. Despite an elevated human biting rate in the absence of large herbivores, we estimated that the potential for RVFV transmission to humans doubles in the presence of large herbivores. These results demonstrate that multiple effects of biodiversity loss on vectors can lead to counterintuitive outcomes for human disease risk.
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Affiliation(s)
- David P Tchouassi
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Baldwyn Torto
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Rosemary Sang
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | | | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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11
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Ezenwa VO, Civitello DJ, Barton BT, Becker DJ, Brenn-White M, Classen AT, Deem SL, Johnson ZE, Kutz S, Malishev M, Penczykowski RM, Preston DL, Vannatta JT, Koltz AM. Infectious Diseases, Livestock, and Climate: A Vicious Cycle? Trends Ecol Evol 2020; 35:959-962. [PMID: 33039158 PMCID: PMC7539894 DOI: 10.1016/j.tree.2020.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 01/29/2023]
Abstract
Ruminant livestock are a significant contributor to global methane emissions. Infectious diseases have the potential to exacerbate these contributions by elevating methane outputs associated with animal production. With the increasing spread of many infectious diseases, the emergence of a vicious climate–livestock–disease cycle is a looming threat.
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Affiliation(s)
- Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30606, USA.
| | | | - Brandon T Barton
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | - Daniel J Becker
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Maris Brenn-White
- Institute for Conservation Medicine, Saint Louis Zoo, St. Louis, MO 63110, USA
| | - Aimée T Classen
- The Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor 48109, USA
| | - Sharon L Deem
- Institute for Conservation Medicine, Saint Louis Zoo, St. Louis, MO 63110, USA
| | - Zoë E Johnson
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA
| | - Susan Kutz
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | | | | | - Daniel L Preston
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - J Trevor Vannatta
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Amanda M Koltz
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
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12
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Richards RL, Cleveland CA, Hall RJ, Tchindebet Ouakou P, Park AW, Ruiz-Tiben E, Weiss A, Yabsley MJ, Ezenwa VO. Identifying correlates of Guinea worm (Dracunculus medinensis) infection in domestic dog populations. PLoS Negl Trop Dis 2020; 14:e0008620. [PMID: 32925916 PMCID: PMC7515199 DOI: 10.1371/journal.pntd.0008620] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/24/2020] [Accepted: 07/20/2020] [Indexed: 12/21/2022] Open
Abstract
Few human infectious diseases have been driven as close to eradication as dracunculiasis, caused by the Guinea worm parasite (Dracunculus medinensis). The number of human cases of Guinea worm decreased from an estimated 3.5 million in 1986 to mere hundreds by the 2010s. In Chad, domestic dogs were diagnosed with Guinea worm for the first time in 2012, and the numbers of infected dogs have increased annually. The presence of the parasite in a non-human host now challenges efforts to eradicate D. medinensis, making it critical to understand the factors that correlate with infection in dogs. In this study, we evaluated anthropogenic and environmental factors most predictive of detection of D. medinensis infection in domestic dog populations in Chad. Using boosted regression tree models to identify covariates of importance for predicting D. medinensis infection at the village and spatial hotspot levels, while controlling for surveillance intensity, we found that the presence of infection in a village was predicted by a combination of demographic (e.g. fishing village identity, dog population size), geographic (e.g. local variation in elevation), and climatic (e.g. precipitation and temperature) factors, which differed between northern and southern villages. In contrast, the presence of a village in a spatial infection hotspot, was primarily predicted by geography and climate. Our findings suggest that factors intrinsic to individual villages are highly predictive of the detection of Guinea worm parasite presence, whereas village membership in a spatial infection hotspot is largely determined by location and climate. This study provides new insight into the landscape-scale epidemiology of a debilitating parasite and can be used to more effectively target ongoing research and possibly eradication and control efforts.
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Affiliation(s)
- Robert L. Richards
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, United States of America
| | - Christopher A. Cleveland
- Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America
| | - Richard J. Hall
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | | | - Andrew W. Park
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | | | - Adam Weiss
- The Carter Center, Atlanta, Georgia, United States of America
| | - Michael J. Yabsley
- Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America
| | - Vanessa O. Ezenwa
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
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13
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Gawriluk TR, Simkin J, Hacker CK, Kimani JM, Kiama SG, Ezenwa VO, Seifert AW. Complex Tissue Regeneration in Mammals Is Associated With Reduced Inflammatory Cytokines and an Influx of T Cells. Front Immunol 2020; 11:1695. [PMID: 32849592 PMCID: PMC7427103 DOI: 10.3389/fimmu.2020.01695] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/25/2020] [Indexed: 12/12/2022] Open
Abstract
While mammals tend to repair injuries, other adult vertebrates like salamanders and fish regenerate damaged tissue. One prominent hypothesis offered to explain an inability to regenerate complex tissue in mammals is a bias during healing toward strong adaptive immunity and inflammatory responses. Here we directly test this hypothesis by characterizing part of the immune response during regeneration in spiny mice (Acomys cahirinus and Acomys percivali) vs. fibrotic repair in Mus musculus. By directly quantifying cytokines during tissue healing, we found that fibrotic repair was associated with a greater release of pro-inflammatory cytokines (i.e., IL-6, CCL2, and CXCL1) during acute inflammation in the wound microenvironment. However, reducing inflammation via COX-2 inhibition was not sufficient to reduce fibrosis or induce a regenerative response, suggesting that inflammatory strength does not control how an injury heals. Although regeneration was associated with lower concentrations of many inflammatory markers, we measured a comparatively larger influx of T cells into regenerating ear tissue and detected a local increase in the T cell associated cytokines IL-12 and IL-17 during the proliferative phase of regeneration. Taken together, our data demonstrate that a strong adaptive immune response is not antagonistic to regeneration and that other mechanisms likely explain the distribution of regenerative ability in vertebrates.
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Affiliation(s)
- Thomas R. Gawriluk
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Jennifer Simkin
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Corin K. Hacker
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - John M. Kimani
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
| | - Stephen G. Kiama
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
| | - Vanessa O. Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, United States
- Department of Infectious Disease, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Ashley W. Seifert
- Department of Biology, University of Kentucky, Lexington, KY, United States
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
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14
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Shearer CL, Ezenwa VO. Rainfall as a driver of seasonality in parasitism. Int J Parasitol Parasites Wildl 2020; 12:8-12. [PMID: 32346510 PMCID: PMC7183095 DOI: 10.1016/j.ijppaw.2020.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 11/19/2022]
Abstract
Parasite burdens are known to vary seasonally in wildlife, and rainfall is one key aspect of seasonality that has been linked to parasitism in a range of systems. Rainfall can have immediate effects on parasitism rates by affecting parasite survival and movement in the environment, or it can have delayed effects by affecting host susceptibility to parasites through changes in host body condition or immune function. In this study, we examined how helminth infection in a wild ungulate (Grant's gazelle, Nanger granti) is impacted by seasonal changes in rainfall. We looked at how the burdens of three helminth parasites varied in relation to current (immediate effect) and prior (delayed effect) rainfall by comparing parasite fecal egg and larval counts to rainfall 0, 1, and 2 months prior to parasite sampling. We found burdens of all three parasites to be negatively associated with rainfall, and that delayed effects were stronger than immediate effects. Our findings implicate rainfall as a driver of seasonal variation in infection and suggest one important mechanism may be through delayed effects on host susceptibility.
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Affiliation(s)
| | - Vanessa O. Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, USA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
- Corresponding author. Odum School of Ecology, University of Georgia, 140 E. Green Street, Athens, GA, USA.
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15
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Cyr JL, Gawriluk TR, Kimani JM, Rada B, Watford WT, Kiama SG, Seifert AW, Ezenwa VO. Regeneration-Competent and -Incompetent Murids Differ in Neutrophil Quantity and Function. Integr Comp Biol 2020; 59:1138-1149. [PMID: 30989211 DOI: 10.1093/icb/icz023] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Regeneration is rare in mammals, but spiny mice (Acomys spp.) naturally regenerate skin and ear holes. Inflammation is thought to inhibit regeneration during wound healing, but aspects of inflammation contribute to both regeneration and pathogen defense. We compared neutrophil traits among uninjured, regeneration-competent (Acomys: A. cahirinus, A. kempi, A. percivali) and -incompetent (Mus musculus: Swiss Webster, wild-caught strains) murids to test for constitutive differences in neutrophil quantity and function between these groups. Neutrophil quantity differed significantly among species. In blood, Acomys had lower percentages of circulating neutrophils than Mus; and in bone marrow, Acomys had higher percentages of band neutrophils and lower percentages of segmented neutrophils. Functionally, Acomys and Mus neutrophils did not differ in their ability to migrate or produce reactive oxygen species, but Acomys neutrophils phagocytosed more fungal zymosan. Despite this enhanced phagocytosis activity, Acomys neutrophils were not more effective than Mus neutrophils at killing Escherichia coli. Interestingly, whole blood bacteria killing was dominated by serum in Acomys versus neutrophils only or neutrophils and serum in Mus, suggesting that Acomys primarily rely on serum to kill bacteria whereas Mus do not. These subtle differences in neutrophil traits may allow regeneration-competent species to offset damaging effects of inflammation without compromising pathogen defense.
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Affiliation(s)
- Jennifer L Cyr
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Thomas R Gawriluk
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - John M Kimani
- Department of Veterinary Anatomy and Physiology, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Balázs Rada
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Wendy T Watford
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Stephen G Kiama
- Department of Veterinary Anatomy and Physiology, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Ashley W Seifert
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA.,Department of Veterinary Anatomy and Physiology, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.,Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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16
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Abstract
An association between malaria and risk for death among patients with Ebola virus disease has suggested within-host interactions between Plasmodium falciparum parasites and Ebola virus. To determine whether such an interaction might also influence the probability of acquiring either infection, we used a large snapshot surveillance study from rural Gabon to test if past exposure to Ebola virus is associated with current infection with Plasmodium spp. during nonepidemic conditions. We found a strong positive association, on population and individual levels, between seropositivity for antibodies against Ebola virus and the presence of Plasmodium parasites in the blood. According to a multiple regression model accounting for other key variables, antibodies against Ebola virus emerged as the strongest individual-level risk factor for acquiring malaria. Our results suggest that within-host interactions between malaria parasites and Ebola virus may underlie epidemiologic associations.
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17
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Gawriluk TR, Simkin J, Hacker CK, Kimani JM, Kiama SG, Ezenwa VO, Seifert AW. Complex Tissue Regeneration in Mammals Is Associated With Reduced Inflammatory Cytokines and an Influx of T Cells. Front Immunol 2020. [PMID: 32849592 DOI: 10.3389/fimmu.2020.01695/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2023] Open
Abstract
While mammals tend to repair injuries, other adult vertebrates like salamanders and fish regenerate damaged tissue. One prominent hypothesis offered to explain an inability to regenerate complex tissue in mammals is a bias during healing toward strong adaptive immunity and inflammatory responses. Here we directly test this hypothesis by characterizing part of the immune response during regeneration in spiny mice (Acomys cahirinus and Acomys percivali) vs. fibrotic repair in Mus musculus. By directly quantifying cytokines during tissue healing, we found that fibrotic repair was associated with a greater release of pro-inflammatory cytokines (i.e., IL-6, CCL2, and CXCL1) during acute inflammation in the wound microenvironment. However, reducing inflammation via COX-2 inhibition was not sufficient to reduce fibrosis or induce a regenerative response, suggesting that inflammatory strength does not control how an injury heals. Although regeneration was associated with lower concentrations of many inflammatory markers, we measured a comparatively larger influx of T cells into regenerating ear tissue and detected a local increase in the T cell associated cytokines IL-12 and IL-17 during the proliferative phase of regeneration. Taken together, our data demonstrate that a strong adaptive immune response is not antagonistic to regeneration and that other mechanisms likely explain the distribution of regenerative ability in vertebrates.
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Affiliation(s)
- Thomas R Gawriluk
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Jennifer Simkin
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Corin K Hacker
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - John M Kimani
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
| | - Stephen G Kiama
- Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, United States.,Department of Infectious Disease, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Ashley W Seifert
- Department of Biology, University of Kentucky, Lexington, KY, United States.,Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
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18
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Park AW, Ezenwa VO. Characterising interactions between co-infecting parasites using age-intensity profiles. Int J Parasitol 2019; 50:23-26. [PMID: 31846621 DOI: 10.1016/j.ijpara.2019.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/28/2019] [Accepted: 11/08/2019] [Indexed: 11/26/2022]
Abstract
Interactions between co-infecting parasite species can impact transmission. Whether co-infection is beneficial or detrimental to a target parasite, and whether the mechanism involves changes in host susceptibility or parasite clearance, can be difficult to assess. We demonstrate the potential for host age-parasite intensity curves to allow assessment of these factors. A model is developed to generate predictions and test these predictions using helminth parasites of white-tailed deer (Odocoileus virginianus). We identify three beneficial interactions involving five helminth species, including susceptibility and clearance-based mechanisms. Our results suggest that analysis of age-intensity data represents a new tool for assessing the nature and strength of co-infecting parasite interactions.
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Affiliation(s)
- Andrew W Park
- Odum School of Ecology, Dept. of Infectious Diseases, College of Veterinary Medicine, and Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, United States.
| | - Vanessa O Ezenwa
- Odum School of Ecology, Dept. of Infectious Diseases, College of Veterinary Medicine, and Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, United States
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19
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Seguel M, Beechler BR, Coon CC, Snyder PW, Spaan JM, Jolles AE, Ezenwa VO. Immune stability predicts tuberculosis infection risk in a wild mammal. Proc Biol Sci 2019; 286:20191401. [PMID: 31575363 DOI: 10.1098/rspb.2019.1401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Immunity is one of the most variable phenotypic traits in animals; however, some individuals may show less fluctuation in immune traits, resulting in stable patterns of immune variation over time. It is currently unknown whether immune variation has consequences for infectious disease risk. In this study, we identified moderately stable immune traits in wild African buffalo and asked whether the stability of these traits affected bovine tuberculosis (TB) infection risk. We found that adaptive immune traits such as the level of interferon-γ (IFN-γ) released after white blood cell stimulation, the number of circulating lymphocytes and the level of antibodies against bovine adenovirus-3 were moderately repeatable (i.e. stable) over time, whereas parameters related to innate immunity either had low repeatability (circulating eosinophil numbers) or were not repeatable (e.g. neutrophil numbers, plasma bacteria killing capacity). Intriguingly, individuals with more repeatable IFN-γ and lymphocyte levels were at a significantly higher risk of acquiring TB infection. In stark contrast, average IFN-γ and lymphocyte levels were poor predictors of TB risk, indicating that immune variability rather than absolute response level better captured variation in disease susceptibility. This work highlights the important and under-appreciated role of immune variability as a predictor of infection risk.
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Affiliation(s)
- Mauricio Seguel
- Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Brianna R Beechler
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - Courtney C Coon
- Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, South Africa.,Felidae Conservation Fund, Mill Valley, CA, USA
| | - Paul W Snyder
- Odum School of Ecology, University of Georgia, Athens, GA, USA.,Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Johannie M Spaan
- College of Osteopathic Medicine of the Pacific Northwest, Western University of Health Sciences, Lebanon, OR, USA
| | - Anna E Jolles
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA.,Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, USA.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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20
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Tavalire HF, Hoal EG, le Roex N, van Helden PD, Ezenwa VO, Jolles AE. Risk alleles for tuberculosis infection associate with reduced immune reactivity in a wild mammalian host. Proc Biol Sci 2019; 286:20190914. [PMID: 31311473 PMCID: PMC6661349 DOI: 10.1098/rspb.2019.0914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Integrating biological processes across scales remains a central challenge in disease ecology. Genetic variation drives differences in host immune responses, which, along with environmental factors, generates temporal and spatial infection patterns in natural populations that epidemiologists seek to predict and control. However, genetics and immunology are typically studied in model systems, whereas population-level patterns of infection status and susceptibility are uniquely observable in nature. Despite obvious causal connections, organizational scales from genes to host outcomes to population patterns are rarely linked explicitly. Here we identify two loci near genes involved in macrophage (phagocyte) activation and pathogen degradation that additively increase risk of bovine tuberculosis infection by up to ninefold in wild African buffalo. Furthermore, we observe genotype-specific variation in IL-12 production indicative of variation in macrophage activation. Here, we provide measurable differences in infection resistance at multiple scales by characterizing the genetic and inflammatory variation driving patterns of infection in a wild mammal.
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Affiliation(s)
- Hannah F Tavalire
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Eileen G Hoal
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Nikki le Roex
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Paul D van Helden
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Anna E Jolles
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.,College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
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21
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Beechler BR, Boersma KS, Buss PE, Coon CAC, Gorsich EE, Henrichs BS, Siepielski AM, Spaan JM, Spaan RS, Ezenwa VO, Jolles AE. Bovine tuberculosis disturbs parasite functional trait composition in African buffalo. Proc Natl Acad Sci U S A 2019; 116:14645-14650. [PMID: 31262813 PMCID: PMC6642339 DOI: 10.1073/pnas.1903674116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Novel parasites can have wide-ranging impacts, not only on host populations, but also on the resident parasite community. Historically, impacts of novel parasites have been assessed by examining pairwise interactions between parasite species. However, parasite communities are complex networks of interacting species. Here we used multivariate taxonomic and trait-based approaches to determine how parasite community composition changed when African buffalo (Syncerus caffer) acquired an emerging disease, bovine tuberculosis (BTB). Both taxonomic and functional parasite richness increased significantly in animals that acquired BTB than in those that did not. Thus, the presence of BTB seems to catalyze extraordinary shifts in community composition. There were no differences in overall parasite taxonomic composition between infected and uninfected individuals, however. The trait-based analysis revealed an increase in direct-transmitted, quickly replicating parasites following BTB infection. This study demonstrates that trait-based approaches provide insight into parasite community dynamics in the context of emerging infections.
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Affiliation(s)
- Brianna R Beechler
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331;
| | - Kate S Boersma
- Department of Biology, University of San Diego, San Diego, CA 92110
| | - Peter E Buss
- Veterinary Wildlife Services, South African National Parks, Kruger National Park, Skukuza 1350, South Africa
| | - Courtney A C Coon
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331
- Felidae Conservation Fund, Mill Valley, CA 94941
| | - Erin E Gorsich
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331
- Zeeman Institute: Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry CV4 7AL, United Kingdom
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Brian S Henrichs
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331
| | - Adam M Siepielski
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
| | - Johannie M Spaan
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331
| | - Robert S Spaan
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331
| | - Vanessa O Ezenwa
- Odum School of Ecology & Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602
| | - Anna E Jolles
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331
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22
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Hodgkinson JE, Kaplan RM, Kenyon F, Morgan ER, Park AW, Paterson S, Babayan SA, Beesley NJ, Britton C, Chaudhry U, Doyle SR, Ezenwa VO, Fenton A, Howell SB, Laing R, Mable BK, Matthews L, McIntyre J, Milne CE, Morrison TA, Prentice JC, Sargison ND, Williams DJL, Wolstenholme AJ, Devaney E. Refugia and anthelmintic resistance: Concepts and challenges. Int J Parasitol Drugs Drug Resist 2019; 10:51-57. [PMID: 31125837 PMCID: PMC6531808 DOI: 10.1016/j.ijpddr.2019.05.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/10/2019] [Accepted: 05/12/2019] [Indexed: 12/17/2022]
Abstract
Anthelmintic resistance is a threat to global food security. In order to alleviate the selection pressure for resistance and maintain drug efficacy, management strategies increasingly aim to preserve a proportion of the parasite population in 'refugia', unexposed to treatment. While persuasive in its logic, and widely advocated as best practice, evidence for the ability of refugia-based approaches to slow the development of drug resistance in parasitic helminths is currently limited. Moreover, the conditions needed for refugia to work, or how transferable those are between parasite-host systems, are not known. This review, born of an international workshop, seeks to deconstruct the concept of refugia and examine its assumptions and applicability in different situations. We conclude that factors potentially important to refugia, such as the fitness cost of drug resistance, the degree of mixing between parasite sub-populations selected through treatment or not, and the impact of parasite life-history, genetics and environment on the population dynamics of resistance, vary widely between systems. The success of attempts to generate refugia to limit anthelmintic drug resistance are therefore likely to be highly dependent on the system in hand. Additional research is needed on the concept of refugia and the underlying principles for its application across systems, as well as empirical studies within systems that prove and optimise its usefulness.
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Affiliation(s)
- Jane E Hodgkinson
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Ray M Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Fiona Kenyon
- Moredun Research Institute, Pentlands Science Park, Edinburgh, EH26 0PZ, UK
| | - Eric R Morgan
- School of Biological Sciences, Queen's University Belfast, Chlorine Gardens, Belfast, BT9 5BL, UK
| | - Andrew W Park
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA; Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, L69 7ZB, UK
| | - Simon A Babayan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Nicola J Beesley
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Collette Britton
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Umer Chaudhry
- Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
| | - Stephen R Doyle
- Wellcome Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA; Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, L69 7ZB, UK
| | - Sue B Howell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Roz Laing
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Barbara K Mable
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Louise Matthews
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Jennifer McIntyre
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Catherine E Milne
- SRUC, Peter Wilson Building, West Mains Road, Edinburgh, EH9 3JG, UK
| | - Thomas A Morrison
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Jamie C Prentice
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK
| | - Neil D Sargison
- Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
| | - Diana J L Williams
- Institute of Infection and Global Health, University of Liverpool, Liverpool, L69 7ZJ, UK
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Eileen Devaney
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G61 1QH, UK.
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23
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Spaan RS, Epps CW, Ezenwa VO, Jolles AE. Why did the buffalo cross the park? Resource shortages, but not infections, drive dispersal in female African buffalo ( Syncerus caffer). Ecol Evol 2019; 9:5651-5663. [PMID: 31160988 PMCID: PMC6540691 DOI: 10.1002/ece3.5145] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/06/2019] [Accepted: 03/13/2019] [Indexed: 12/04/2022] Open
Abstract
Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management implications, particularly with respect to disease spread. Although the role of adult dispersal in spreading disease has been documented, the potential influence of disease on dispersal has received little attention. African buffalo (Syncerus caffer) are wide-ranging and harbor many pathogens that can affect nearby livestock. Dispersal of adult buffalo has been described, but ecological and social drivers of buffalo dispersal are poorly understood. We investigated drivers of adult buffalo dispersal during a 4-year longitudinal study at Kruger National Park, South Africa. We monitored the spatial movement of 304 female buffalo in two focal areas using satellite and radio collars, capturing each buffalo every 6 months to assess animal traits and disease status. We used generalized linear mixed models to determine whether likelihood of dispersal for individual female buffalo was influenced by animal traits, herd identity, environmental variables, gastrointestinal parasites, or microparasite infections. The likelihood and drivers of buffalo dispersal varied by herd, area, and year. In the Lower Sabie herd, where resources were abundant, younger individuals were more likely to disperse, with most dispersal occurring in the early wet season and during an unusually dry year, 2009. In the resource-poor Crocodile Bridge area, buffalo in poor condition were most likely to disperse. Our findings suggest that dispersal of female buffalo is driven by either seasonal (Lower Sabie) or perhaps social (Crocodile Bridge) resource restriction, indicating resource limitation and dispersal decisions are tightly linked for this social ungulate. We found no direct effects of infections on buffalo dispersal, assuaging fears that highly infectious individuals might be more prone to dispersing, which could accelerate the spatial spread of infectious diseases.
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Affiliation(s)
- Robert S. Spaan
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon
| | - Clinton W. Epps
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon
| | - Vanessa O. Ezenwa
- Department of Infectious Diseases, Odum School of EcologyUniversity of GeorgiaAthensGeorgia
| | - Anna E. Jolles
- Department of Biomedical SciencesOregon State UniversityCorvallisOregon
- Department of Integrative BiologyOregon State UniversityCorvallisOregon
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24
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Stephens PR, Altizer S, Ezenwa VO, Gittleman JL, Moan E, Han B, Huang S, Pappalardo P. Parasite sharing in wild ungulates and their predators: Effects of phylogeny, range overlap, and trophic links. J Anim Ecol 2019; 88:1017-1028. [PMID: 30921468 DOI: 10.1111/1365-2656.12987] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/26/2019] [Indexed: 12/12/2022]
Abstract
Understanding factors that facilitate interspecific pathogen transmission is a central issue for conservation, agriculture, and human health. Past work showed that host phylogenetic relatedness and geographical proximity can increase cross-species transmission, but further work is needed to examine the importance of host traits, and species interactions such as predation, in determining the degree to which parasites are shared between hosts. Here we consider the factors that predict patterns of parasite sharing across a diverse assemblage of 116 wild ungulates (i.e., hoofed mammals in the Artiodactyla and Perissodactyla) and nearly 900 species of micro- and macroparasites, controlling for differences in total parasite richness and host sampling effort. We also consider the effects of trophic links on parasite sharing between ungulates and carnivores. We tested for the relative influence of range overlap, phylogenetic distance, body mass, and ecological dissimilarity (i.e., the distance separating species in a Euclidean distance matrix based on standardized traits) on parasite sharing. We also tested for the effects of variation in study effort as a potential source of bias in our data, and tested whether carnivores reported to feed on ungulates have more ungulate parasites than those that use other resources. As in other groups, geographical range overlap and phylogenetic similarity predicted greater parasite community similarity in ungulates. Ecological dissimilarity showed a weak negative relationship with parasite sharing. Counter to our expectations, differences, not similarity, in host body mass predicted greater parasite sharing between pairs of ungulate hosts. Pairs of well-studied host species showed higher overlap than poorly studied species, although including sampling effort did not reduce the importance of biological traits in our models. Finally, carnivores that feed on ungulates harboured a greater richness of ungulate helminths. Overall, we show that the factors that predict parasite sharing in wild ungulates are similar to those known for other mammal groups, and demonstrate the importance of controlling for heterogeneity in host sampling effort in future analyses of parasite sharing. We also show that ecological interactions, in this case trophic links via predation, can allow sharing of some parasite species among distantly related host species.
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Affiliation(s)
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, Georgia
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, Georgia.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | | | - Emili Moan
- Department of Statistics, North Carolina State University, Raleigh, North Carolina
| | - Barbara Han
- Cary Institute of Ecosystem Studies, Millbrook, New York
| | - Shan Huang
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Frankfurt (Main), Germany
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25
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Tavalire HF, Beechler BR, Buss PE, Gorsich EE, Hoal EG, le Roex N, Spaan JM, Spaan RS, van Helden PD, Ezenwa VO, Jolles AE. Context-dependent costs and benefits of tuberculosis resistance traits in a wild mammalian host. Ecol Evol 2018; 8:12712-12726. [PMID: 30619576 PMCID: PMC6308860 DOI: 10.1002/ece3.4699] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 10/02/2018] [Accepted: 10/12/2018] [Indexed: 12/24/2022] Open
Abstract
Disease acts as a powerful driver of evolution in natural host populations, yet individuals in a population often vary in their susceptibility to infection. Energetic trade-offs between immune and reproductive investment lead to the evolution of distinct life history strategies, driven by the relative fitness costs and benefits of resisting infection. However, examples quantifying the cost of resistance outside of the laboratory are rare. Here, we observe two distinct forms of resistance to bovine tuberculosis (bTB), an important zoonotic pathogen, in a free-ranging African buffalo (Syncerus caffer) population. We characterize these phenotypes as "infection resistance," in which hosts delay or prevent infection, and "proliferation resistance," in which the host limits the spread of lesions caused by the pathogen after infection has occurred. We found weak evidence that infection resistance to bTB may be heritable in this buffalo population (h 2 = 0.10) and comes at the cost of reduced body condition and marginally reduced survival once infected, but also associates with an overall higher reproductive rate. Infection-resistant animals thus appear to follow a "fast" pace-of-life syndrome, in that they reproduce more quickly but die upon infection. In contrast, proliferation resistance had no apparent costs and was associated with measures of positive host health-such as having a higher body condition and reproductive rate. This study quantifies striking phenotypic variation in pathogen resistance and provides evidence for a link between life history variation and a disease resistance trait in a wild mammalian host population.
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Affiliation(s)
- Hannah F. Tavalire
- Department of Integrative BiologyOregon State UniversityCorvallisOregon
- The Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
- Present address:
Prevention Science InstituteUniversity of OregonEugeneOregon
- Present address:
Institute of Ecology and EvolutionUniversity of OregonEugeneOregon
| | | | | | - Erin E. Gorsich
- College of Veterinary MedicineOregon State UniversityCorvallisOregon
- Present address:
Erin E. Gorsich, Zeeman Institute: Systems Biology and Infectious Disease Epidemiology Research (SBIDER)University of WarwickCoventryUK
- Present address:
School of Life SciencesUniversity of WarwickCoventryUK
| | - Eileen G. Hoal
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health SciencesStellenbosch UniversityTygerbergSouth Africa
| | - Nikki le Roex
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health SciencesStellenbosch UniversityTygerbergSouth Africa
| | - Johannie M. Spaan
- Department of Integrative BiologyOregon State UniversityCorvallisOregon
| | - Robert S. Spaan
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon
| | - Paul D. van Helden
- South African Medical Research Council, DST/NRF Centre of Excellence for Biomedical TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health SciencesStellenbosch UniversityTygerbergSouth Africa
| | - Vanessa O. Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary MedicineUniversity of GeorgiaAthensGeorgia
| | - Anna E. Jolles
- Department of Integrative BiologyOregon State UniversityCorvallisOregon
- College of Veterinary MedicineOregon State UniversityCorvallisOregon
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Ezenwa VO, Worsley-Tonks KEL. Social living simultaneously increases infection risk and decreases the cost of infection. Proc Biol Sci 2018; 285:rspb.2018.2142. [PMID: 30487314 DOI: 10.1098/rspb.2018.2142] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Accepted: 11/05/2018] [Indexed: 01/05/2023] Open
Abstract
Elevated parasite infection risk is considered to be a near-universal cost of social living. However, living in groups may also provide benefits that reduce the negative impacts of infection. These potential 'tolerance' benefits of living socially are theoretically possible, but have rarely been described. In this study, we used an anthelmintic treatment experiment in wild Grant's gazelles (Nanger granti), who are commonly infected with gastrointestinal nematodes (GIN), to show that social living confers both costs and benefits related to GIN parasitism. We show that although larger group size increases GIN infection risk, a key cost of GIN infection-the suppression of food intake-is simultaneously moderated by living in larger groups. Our findings help illuminate the complex role parasites play in the evolution of host social behaviour.
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Affiliation(s)
- Vanessa O Ezenwa
- Odum School of Ecology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA .,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Katherine E L Worsley-Tonks
- Odum School of Ecology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.,Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN, USA
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Abbate JL, Ezenwa VO, Guégan JF, Choisy M, Nacher M, Roche B. Disentangling complex parasite interactions: Protection against cerebral malaria by one helminth species is jeopardized by co-infection with another. PLoS Negl Trop Dis 2018; 12:e0006483. [PMID: 29746467 PMCID: PMC5963812 DOI: 10.1371/journal.pntd.0006483] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 05/22/2018] [Accepted: 04/30/2018] [Indexed: 12/24/2022] Open
Abstract
Multi-species interactions can often have non-intuitive consequences. However, the study of parasite interactions has rarely gone beyond the effects of pairwise combinations of species, and the outcomes of multi-parasite interactions are poorly understood. We investigated the effects of co-infection by four gastrointestinal helminth species on the development of cerebral malaria among Plasmodium falciparum-infected patients. We characterized associations among the helminth parasite infra-community, and then tested for independent (direct) and co-infection dependent (indirect) effects of helminths on cerebral malaria risk. We found that infection by Ascaris lumbricoides and Trichuris trichiura were both associated with direct reductions in cerebral malaria risk. However, the benefit of T. trichiura infection was halved in the presence of hookworm, revealing a strong indirect effect. Our study suggests that the outcome of interactions between two parasite species can be significantly modified by a third, emphasizing the critical role that parasite community interactions play in shaping infection outcomes.
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Affiliation(s)
- Jessica L Abbate
- UMMISCO, IRD / Sorbonne Université, Bondy, France.,MIVEGEC, IRD, CNRS, Université Montpellier, Montpellier, France
| | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | | | - Marc Choisy
- MIVEGEC, IRD, CNRS, Université Montpellier, Montpellier, France.,Oxford University Clinical Research Unit, Hanoi, Vietnam
| | - Mathieu Nacher
- CIC INSERM 1424, Centre Hospitalier de Cayenne, Cayenne, French Guiana.,EA3593, Ecosystèmes Amazoniens et Pathologie Tropicale, Université de Guyane, Cayenne, French Guiana
| | - Benjamin Roche
- UMMISCO, IRD / Sorbonne Université, Bondy, France.,MIVEGEC, IRD, CNRS, Université Montpellier, Montpellier, France.,Departamento de Etología, Fauna Silvestre y Animales de Laboratorio, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, México
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Beechler BR, Jolles AE, Budischak SA, Corstjens PLAM, Ezenwa VO, Smith M, Spaan RS, van Dam GJ, Steinauer ML. Host immunity, nutrition and coinfection alter longitudinal infection patterns of schistosomes in a free ranging African buffalo population. PLoS Negl Trop Dis 2017; 11:e0006122. [PMID: 29253882 PMCID: PMC5755937 DOI: 10.1371/journal.pntd.0006122] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 01/05/2018] [Accepted: 11/20/2017] [Indexed: 11/19/2022] Open
Abstract
Schistosomes are trematode parasites of global importance, causing infections in millions of people, livestock, and wildlife. Most studies on schistosomiasis, involve human subjects; as such, there is a paucity of longitudinal studies investigating parasite dynamics in the absence of intervention. As a consequence, despite decades of research on schistosomiasis, our understanding of its ecology in natural host populations is centered around how environmental exposure and acquired immunity influence acquisition of parasites, while very little is known about the influence of host physiology, coinfection and clearance in the absence of drug treatment. We used a 4-year study in free-ranging African buffalo to investigate natural schistosome dynamics. We asked (i) what are the spatial and temporal patterns of schistosome infections; (ii) how do parasite burdens vary over time within individual hosts; and (iii) what host factors (immunological, physiological, co-infection) and environmental factors (season, location) explain patterns of schistosome acquisition and loss in buffalo? Schistosome infections were common among buffalo. Microgeographic structure explained some variation in parasite burdens among hosts, indicating transmission hotspots. Overall, parasite burdens ratcheted up over time; however, gains in schistosome abundance in the dry season were partially offset by losses in the wet season, with some hosts demonstrating complete clearance of infection. Variation among buffalo in schistosome loss was associated with immunologic and nutritional factors, as well as co-infection by the gastrointestinal helminth Cooperia fuelleborni. Our results demonstrate that schistosome infections are surprisingly dynamic in a free-living mammalian host population, and point to a role for host factors in driving variation in parasite clearance, but not parasite acquisition which is driven by seasonal changes and spatial habitat utilization. Our study illustrates the power of longitudinal studies for discovering mechanisms underlying parasite dynamics in individual animals and populations.
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Affiliation(s)
- Brianna R. Beechler
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States of America
| | - Anna E. Jolles
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States of America
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
| | - Sarah A. Budischak
- Odum School of Ecology, University of Georgia, Athens, GA, United States of America
| | - Paul L. A. M. Corstjens
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Vanessa O. Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, United States of America
- College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Mireya Smith
- College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Robert S. Spaan
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, United States of America
| | - Govert J. van Dam
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Michelle L. Steinauer
- College of Osteopathic Medicine of the PNW, Western University of Health Sciences, Lebanon, OR, United States of America
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Ezenwa VO. Helminth-microparasite co-infection in wildlife: lessons from ruminants, rodents and rabbits. Parasite Immunol 2017; 38:527-34. [PMID: 27426017 DOI: 10.1111/pim.12348] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/13/2016] [Indexed: 12/26/2022]
Abstract
Co-infection is now recognized as the natural state of affairs in most hosts and co-infecting parasites interact in a variety of ways that can impact host health and parasite fitness. Interactions between helminths and microparasites have captured particular attention in this regard owing to the ubiquity of helminth infections in many host populations. The mechanistic underpinnings and health implications of co-infection are typically studied in laboratory and clinical settings, but recently studies of wild species have begun to tackle similar issues. Case studies from three wild mammal groups-ruminants, rodents and rabbits-serve to highlight how wild studies are contributing to the broader co-infection literature. This work suggests that wildlife research can generate new and unique insights about helminth-microparasite co-infection that are fostered in part by studying parasite interactions in a natural context. For this reason, increased integration of wild studies with research in human, laboratory and veterinary animal populations can help pave the way towards a more complete understanding of the issue of co-infection.
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Affiliation(s)
- V O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, USA. .,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
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31
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Affiliation(s)
- Sarah A. Budischak
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Department of Ecology and Evolutionary Biology Princeton NJ USA
| | - Dawn O'Neal
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Huyck Preserve & Biological Research Station Rensselaerville NY USA
| | - Anna E. Jolles
- Department of Biomedical Sciences and Department of Integrative BiologyOregon State University Corvallis OR USA
| | - Vanessa O. Ezenwa
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Department of Infectious DiseasesUniversity of Georgia Athens GA USA
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32
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Rajeev M, Mutinda M, Ezenwa VO. Pathogen Exposure in Cattle at the Livestock-Wildlife Interface. Ecohealth 2017; 14:542-551. [PMID: 28470362 DOI: 10.1007/s10393-017-1242-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 03/23/2017] [Indexed: 06/07/2023]
Abstract
Land use is an important driver of variation in human infectious disease risk, but less is known about how land use affects disease risk in livestock. To understand how land use is associated with disease risk in livestock, we examined patterns of pathogen exposure in cattle across two livestock ranching systems in rural Kenya: private ranches with low- to medium-intensity cattle production and high wildlife densities, and group ranches with high-intensity cattle production and low wildlife densities. We surveyed cattle from six ranches for three pathogens: Brucella spp., bovine viral diarrhea virus (BVDV) and Leptospira serovar Hardjo. We found that exposure risk for Leptospira was higher on private ranches than on group ranches, but there was no difference in exposure by ranch type for Brucella or BVDV. We hypothesize that variation in livestock and wildlife contact patterns between ranch types may be driving the pattern observed for Leptospira exposure and that the different relationships we found between exposure risk and ranch type by pathogen may be explained by differences in transmission mode. Overall, our results suggest that wildlife-livestock contact patterns may play a key role in shaping pathogen transmission to livestock and that the magnitude of such effects likely depend on characteristics of the pathogen in question.
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Affiliation(s)
- Malavika Rajeev
- Odum School of Ecology, University of Georgia, Athens, GA, 30602-2202, USA
| | | | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, 30602-2202, USA.
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602-2202, USA.
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33
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Spaan JM, Pitts N, Buss P, Beechler B, Ezenwa VO, Jolles AE. Noninvasive measures of stress response in African buffalo (Syncerus caffer) reveal an age-dependent stress response to immobilization. J Mammal 2017. [DOI: 10.1093/jmammal/gyx073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ezenwa VO, Snider MH. Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour. Proc Biol Sci 2017; 283:rspb.2016.0423. [PMID: 27194703 DOI: 10.1098/rspb.2016.0423] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/22/2016] [Indexed: 12/21/2022] Open
Abstract
Parasites are ubiquitous components of the environment that contribute to behavioural and life-history variation among hosts. Although it is well known that host behaviour can affect parasite infection risk and that parasites can alter host behaviour, the potential for dynamic feedback between these processes is poorly characterized. Using Grant's gazelle (Nanger granti) as a model, we tested for reciprocal effects of behaviour on parasites and parasites on behaviour to understand whether behaviour-parasite feedback could play a role in maintaining variation in male reproductive behaviour. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behaviour related to territory maintenance and defence. These results suggest that territorial behaviour promotes the accumulation of parasites in males, and these parasites dampen the very behaviours required for territory maintenance. Our findings suggest that reciprocal feedback between host behaviour and parasitism could be a mechanism maintaining variation in male reproductive behaviour in the system.
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Affiliation(s)
- Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Matthew H Snider
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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35
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Hosseini PR, Mills JN, Prieur-Richard AH, Ezenwa VO, Bailly X, Rizzoli A, Suzán G, Vittecoq M, García-Peña GE, Daszak P, Guégan JF, Roche B. Does the impact of biodiversity differ between emerging and endemic pathogens? The need to separate the concepts of hazard and risk. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160129. [PMID: 28438918 PMCID: PMC5413877 DOI: 10.1098/rstb.2016.0129] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2016] [Indexed: 11/12/2022] Open
Abstract
Biodiversity is of critical value to human societies, but recent evidence that biodiversity may mitigate infectious-disease risk has sparked controversy among researchers. The majority of work on this topic has focused on direct assessments of the relationship between biodiversity and endemic-pathogen prevalence, without disentangling intervening mechanisms; thus study outcomes often differ, fuelling more debate. Here, we suggest two critical changes to the approach researchers take to understanding relationships between infectious disease, both endemic and emerging, and biodiversity that may help clarify sources of controversy. First, the distinct concepts of hazards versus risks need to be separated to determine how biodiversity and its drivers may act differently on each. This distinction is particularly important since it illustrates that disease emergence drivers in humans could be quite different to the general relationship between biodiversity and transmission of endemic pathogens. Second, the interactive relationship among biodiversity, anthropogenic change and zoonotic disease risk, including both direct and indirect effects, needs to be recognized and accounted for. By carefully disentangling these interactions between humans' activities and pathogen circulation in wildlife, we suggest that conservation efforts could mitigate disease risks and hazards in novel ways that complement more typical disease control efforts.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
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Affiliation(s)
- Parviez R Hosseini
- EcoHealth Alliance, 460 West 34th Street - 17th Floor, New York, NY 10001-2320, USA
| | - James N Mills
- Population Biology, Ecology, and Evolution Program, Emory University, 1335 Springdale Road, Northeast, Atlanta, GA 30306, USA
| | | | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 140 East Green Street, Athens, GA 30602-2202, USA
| | - Xavier Bailly
- INRA, UR346 Epidémiologie Animale, 63122 Saint Genès Champanelle, France
| | - Annapaola Rizzoli
- Edmund Mach Foundation, Research and Innovation Centre, 1 Via Edmondo Mach, 38010 San Michele all'Adige, Trentino, Italy
| | - Gerardo Suzán
- Departamento de Etología y Fauna Silvestre, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, Distrito Federal, C.P. 04510, Mexico
- FutureEarth Programme, OneHealth Core Research Programme Domaine du Petit Arbois. Avenue Louis Philibert., 13857 Aix-en-Provence Cedex 3, France
| | - Marion Vittecoq
- Centre de recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France
| | - Gabriel E García-Peña
- Departamento de Etología y Fauna Silvestre, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, Distrito Federal, C.P. 04510, Mexico
- UMR MIVEGEC CNRS 5290/IRD 224/Université de Montpellier, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France
- FutureEarth Programme, OneHealth Core Research Programme Domaine du Petit Arbois. Avenue Louis Philibert., 13857 Aix-en-Provence Cedex 3, France
- Centre de Synthèse et d'Analyse sur la Biodiversité -CESAB. Bâtiment Henri Poincaré, Domaine du Petit Arbois. Avenue Louis Philibert., 13857 Aix-en-Provence Cedex 3, France
| | - Peter Daszak
- EcoHealth Alliance, 460 West 34th Street - 17th Floor, New York, NY 10001-2320, USA
- FutureEarth Programme, OneHealth Core Research Programme Domaine du Petit Arbois. Avenue Louis Philibert., 13857 Aix-en-Provence Cedex 3, France
| | - Jean-François Guégan
- UMR MIVEGEC CNRS 5290/IRD 224/Université de Montpellier, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France
- FutureEarth Programme, OneHealth Core Research Programme Domaine du Petit Arbois. Avenue Louis Philibert., 13857 Aix-en-Provence Cedex 3, France
| | - Benjamin Roche
- UMI IRD/UPMC 209 UMMISCO, 32, avenue Henri Varagnat, 93143 Bondy Cedex, France
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36
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Stephens PR, Pappalardo P, Huang S, Byers JE, Farrell MJ, Gehman A, Ghai RR, Haas SE, Han B, Park AW, Schmidt JP, Altizer S, Ezenwa VO, Nunn CL. Global Mammal Parasite Database version 2.0. Ecology 2017; 98:1476. [DOI: 10.1002/ecy.1799] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Patrick R. Stephens
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - Paula Pappalardo
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - Shan Huang
- Senckenberg Biodiversity and Climate Research Center (BiK-F); Senckenberganlage 25 D-60325 Frankfurt (Main) Germany
| | - James E. Byers
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | | | - Alyssa Gehman
- Department of Zoology; University of British Columbia; Vancouver British Columbia V6T1Z4 Canada
| | - Ria R. Ghai
- Department of Environmental Sciences; Emory University; Atlanta Georgia 30322 USA
| | - Sarah E. Haas
- Inland Fisheries Division; Texas Parks and Wildlife Department; Austin Texas 78744 USA
| | - Barbara Han
- Cary Institute of Ecosystem Ecology; Millbrook New York 12545 USA
| | - Andrew W. Park
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - John P. Schmidt
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - Sonia Altizer
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - Vanessa O. Ezenwa
- Odum School of Ecology; 140 E Green St., University of Georgia; Athens Georgia 30602 USA
| | - Charles L. Nunn
- Biological Sciences; Duke University; Durham North Carolina 27708 USA
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Austin LV, Budischak SA, Ramadhin J, Hoberg EP, Abrams A, Jolles AE, Ezenwa VO. A comparison of two methods for quantifying parasitic nematode fecundity. Parasitol Res 2017; 116:1597-1602. [PMID: 28357577 DOI: 10.1007/s00436-017-5436-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/21/2017] [Indexed: 11/29/2022]
Abstract
Accurate measures of nematode fecundity can provide important information for investigating parasite life history evolution, transmission potential, and effects on host health. Understanding differences among fecundity assessment protocols and standardizing methods, where possible, will enable comparisons across different studies and host and parasite species and systems. Using the trichostrongyle nematode Cooperia fuelleborni isolated from wild African buffalo (Syncerus caffer), we compared egg recovery and enumeration between two methods for measuring the fecundity of female worms. The first method, in utero egg count, involves visual enumeration of the eggs via microscopic inspection of the uterine system. The second method, ex utero egg count, involves dissolving the same specimens from above in a sodium chloride solution to release the eggs from the female's uterus, then enumeration under an inverted microscope. On average, the ex utero method resulted in 34% more eggs than the in utero method. However, results indicate that the two methods used to quantify parasitic nematode fecundity are highly correlated. Thus, while both methods are viable options for estimating relative nematode fecundity, we recommend caution in undertaking comparative studies that utilize egg count data collected using different methods.
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Affiliation(s)
- Lauren V Austin
- Odum School of Ecology, University of Georgia, 140 E. Green St, Athens, GA, 30602, USA.,Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, 310 West Campus Drive, Blacksburg, VA, 24061, USA
| | - Sarah A Budischak
- Odum School of Ecology, University of Georgia, 140 E. Green St, Athens, GA, 30602, USA. .,Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Hall, Princeton, NJ, 08544-2016, USA.
| | - Jessica Ramadhin
- Department of Infectious Diseases, University of Georgia, 510 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Eric P Hoberg
- United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Art Abrams
- United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Anna E Jolles
- Department of Biomedical Sciences and Department of Integrative Biology, Oregon State University, 105 Magruder Hall, Corvallis, OR, 97331, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, 140 E. Green St, Athens, GA, 30602, USA.,Department of Infectious Diseases, University of Georgia, 510 D.W. Brooks Drive, Athens, GA, 30602, USA
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Ezenwa VO, Archie EA, Craft ME, Hawley DM, Martin LB, Moore J, White L. Host behaviour-parasite feedback: an essential link between animal behaviour and disease ecology. Proc Biol Sci 2016; 283:rspb.2015.3078. [PMID: 27053751 DOI: 10.1098/rspb.2015.3078] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/15/2016] [Indexed: 12/18/2022] Open
Abstract
Animal behaviour and the ecology and evolution of parasites are inextricably linked. For this reason, animal behaviourists and disease ecologists have been interested in the intersection of their respective fields for decades. Despite this interest, most research at the behaviour-disease interface focuses either on how host behaviour affects parasites or how parasites affect behaviour, with little overlap between the two. Yet, the majority of interactions between hosts and parasites are probably reciprocal, such that host behaviour feeds back on parasites and vice versa. Explicitly considering these feedbacks is essential for understanding the complex connections between animal behaviour and parasite ecology and evolution. To illustrate this point, we discuss how host behaviour-parasite feedbacks might operate and explore the consequences of feedback for studies of animal behaviour and parasites. For example, ignoring the feedback of host social structure on parasite dynamics can limit the accuracy of predictions about parasite spread. Likewise, considering feedback in studies of parasites and animal personalities may provide unique insight about the maintenance of variation in personality types. Finally, applying the feedback concept to links between host behaviour and beneficial, rather than pathogenic, microbes may shed new light on transitions between mutualism and parasitism. More generally, accounting for host behaviour-parasite feedbacks can help identify critical gaps in our understanding of how key host behaviours and parasite traits evolve and are maintained.
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Affiliation(s)
- Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Elizabeth A Archie
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Meggan E Craft
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN 55108, USA
| | - Dana M Hawley
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Lynn B Martin
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Janice Moore
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Lauren White
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, USA
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McKay AF, Ezenwa VO, Altizer S. Consequences of Food Restriction for Immune Defense, Parasite Infection, and Fitness in Monarch Butterflies. Physiol Biochem Zool 2016; 89:389-401. [DOI: 10.1086/687989] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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40
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Ghai RR, Mutinda M, Ezenwa VO. Limited sharing of tick-borne hemoparasites between sympatric wild and domestic ungulates. Vet Parasitol 2016; 226:167-73. [PMID: 27514903 DOI: 10.1016/j.vetpar.2016.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/30/2016] [Accepted: 07/02/2016] [Indexed: 02/08/2023]
Abstract
Tick-borne hemoparasites (TBHs) are a group of pathogens of concern in animal management because they are associated with a diversity of hosts, including both wild and domestic species. However, little is known about how frequently TBHs are shared across the wildlife-livestock interface in natural settings. Here, we compared the TBHs of wild Grant's gazelle (Nanger granti) and domestic sheep (Ovis aries) in a region of Kenya where these species extensively overlap. Blood samples collected from each species were screened for piroplasm and rickettsial TBHs by PCR-based amplification of 18S/16S ribosomal DNA, respectively. Overall, 99% of gazelle and 66% of sheep were positive for Babesia/Theileria, and 32% of gazelle and 47% sheep were positive for Anaplasma/Ehrlichia. Sequencing a subset of positive samples revealed infections of Theileria and Anaplasma. Sequences sorted into seven phylogenetically distinct genotypes-two Theileria, and five Anaplasma. With the exception of a putatively novel Anaplasma lineage from Grant's gazelle, these genotypes appeared to be divergent forms of previously described species, including T. ovis, A. ovis, A. bovis, and A. platys. Only one genotype, which clustered within the A. platys clade, contained sequences from both gazelle and sheep. This suggests that despite niche, habitat, and phylogenetic overlap, the majority of circulating tick-borne diseases may not be shared between these two focal species.
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Affiliation(s)
- Ria R Ghai
- Odum School of Ecology, University of Georgia, 140 E. Green Street, Athens, GA 30602, USA.
| | - Mathew Mutinda
- Kenya Wildlife Service, P.O. Box 40241-00100, Nairobi, Kenya
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, 140 E. Green Street, Athens, GA 30602, USA; Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA
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41
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Stephens PR, Altizer S, Smith KF, Alonso Aguirre A, Brown JH, Budischak SA, Byers JE, Dallas TA, Jonathan Davies T, Drake JM, Ezenwa VO, Farrell MJ, Gittleman JL, Han BA, Huang S, Hutchinson RA, Johnson P, Nunn CL, Onstad D, Park A, Vazquez-Prokopec GM, Schmidt JP, Poulin R. The macroecology of infectious diseases: a new perspective on global-scale drivers of pathogen distributions and impacts. Ecol Lett 2016; 19:1159-71. [PMID: 27353433 DOI: 10.1111/ele.12644] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/12/2016] [Accepted: 05/31/2016] [Indexed: 01/26/2023]
Abstract
Identifying drivers of infectious disease patterns and impacts at the broadest scales of organisation is one of the most crucial challenges for modern science, yet answers to many fundamental questions remain elusive. These include what factors commonly facilitate transmission of pathogens to novel host species, what drives variation in immune investment among host species, and more generally what drives global patterns of parasite diversity and distribution? Here we consider how the perspectives and tools of macroecology, a field that investigates patterns and processes at broad spatial, temporal and taxonomic scales, are expanding scientific understanding of global infectious disease ecology. In particular, emerging approaches are providing new insights about scaling properties across all living taxa, and new strategies for mapping pathogen biodiversity and infection risk. Ultimately, macroecology is establishing a framework to more accurately predict global patterns of infectious disease distribution and emergence.
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Affiliation(s)
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Katherine F Smith
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 0291, USA
| | - A Alonso Aguirre
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, 22030, USA
| | - James H Brown
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Sarah A Budischak
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - James E Byers
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Tad A Dallas
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - T Jonathan Davies
- Department of Biology, McGill University, Montreal, Quebec, H3A 0G4, Canada
| | - John M Drake
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Maxwell J Farrell
- Department of Biology, McGill University, Montreal, Quebec, H3A 0G4, Canada
| | - John L Gittleman
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Barbara A Han
- Cary Institute of Ecosystem Studies, Millbrook, New York, 12545, USA
| | - Shan Huang
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt, Germany
| | - Rebecca A Hutchinson
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331, USA
| | - Pieter Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Charles L Nunn
- Biological Sciences, Duke University, Durham, NC, 27708, USA
| | - David Onstad
- ITD Data Analysis and Modelling, DuPont Agricultural Biotechnology, Experimental Station E353/317, Wilmington, DE, 19803, USA
| | - Andrew Park
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | | | - John P Schmidt
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Robert Poulin
- Department of Zoology, University of Otago, Dunedin, 9054, New Zealand
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Budischak SA, Hoberg EP, Abrams A, Jolles AE, Ezenwa VO. Experimental insight into the process of parasite community assembly. J Anim Ecol 2016; 85:1222-33. [PMID: 27174037 DOI: 10.1111/1365-2656.12548] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 05/04/2016] [Indexed: 11/27/2022]
Abstract
Community assembly is a fundamental process that has long been a central focus in ecology. Extending community assembly theory to communities of co-infecting parasites, we used a gastrointestinal nematode removal experiment in free-ranging African buffalo to examine the community assembly patterns and processes. We first asked whether reassembled communities differ from undisturbed communities by comparing anthelmintic-treated and control hosts. Next, we examined the temporal dynamics of assembly using a cross-section of communities that reassembled for different periods of time since last experimental removal. Next, we tested for evidence of assembly processes that might drive such reassembly patterns: environmental filtering based on host traits (i.e. habitat patches), interspecific interactions, priority effects and chance dispersal from the environmental pool of infective stages (i.e. the regional species pool). On average, reassembled parasite communities had lower abundance, but were more diverse and even, and these patterns varied tightly with reassembly time. Over time, the communities within treated hosts progressively resembled controls as diversity and evenness decreased, while total abundance increased. Notably, experimental removal allowed us to attribute observed differences in abundance, diversity and evenness to the process of community assembly. During early reassembly, parasite accumulation was biased towards a subordinate species and, by excluding stochastic assembly processes (i.e. chance dispersal and priority effects), we were able to determine that early assembly is deterministic. Later in the reassembly process, we established that host traits, as well as stochastic dispersal from the environmental pool of infective stages, can affect the community composition. Overall, our results suggest that there is a high degree of resiliency and environmental dependence to the worm communities of buffalo. More generally, our data show that both deterministic and stochastic processes may play a role in the assembly of parasite communities of wild hosts, but their relative importance may vary temporally. Consequently, the best strategy for managing reassembling parasite communities may also need to shift over time.
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Affiliation(s)
- Sarah A Budischak
- Odum School of Ecology, University of Georgia, 140 E. Green St, Athens, GA, 30602, USA
| | - Eric P Hoberg
- United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Ave, Bldg. 1180, BARC-East, Beltsville, MD, 20705, USA
| | - Art Abrams
- United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Ave, Bldg. 1180, BARC-East, Beltsville, MD, 20705, USA
| | - Anna E Jolles
- Department of Biomedical Sciences and Department of Integrative Biology, Oregon State University, 700 SW 30th St, Corvallis, OR 97331, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology, University of Georgia, 140 E. Green St, Athens, GA, 30602, USA.,Department of Infectious Diseases, University of Georgia, 140 E Green St, Athens, GA 30602, USA
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43
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Fritzsche McKay A, Ezenwa VO, Altizer S. Unravelling the Costs of Flight for Immune Defenses in the Migratory Monarch Butterfly. Integr Comp Biol 2016; 56:278-89. [PMID: 27260859 DOI: 10.1093/icb/icw056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Migratory animals undergo extreme physiological changes to prepare for and sustain energetically costly movements; one potential change is reduced investment in immune defenses. However, because some migrants have evolved to minimize the energetic demands of movement (for example, through the temporary atrophy of non-essential organs such as those involved in reproduction), migratory animals could potentially avoid immunosuppression during long-distance journeys. In this study, we used a tethered flight mill to examine immune consequences of experimentally induced powered flight in eastern North American monarch butterflies. These butterflies undergo an annual two-way long-distance migration each year from as far north as Canada to wintering sites in Central Mexico. We quantified immune measures as a function of categorical flight treatment (flown versus control groups) and continuous measures of flight effort (e.g., flight distance, duration, and measures of efficiency). We also examined whether relationships between flight and immune measures depended on reproductive investment by experimentally controlling whether monarchs were reproductive or in state of reproductive diapause (having atrophied reproductive organs) prior to flight. Of the three immune responses we measured, hemocyte concentration (the number of immune cells) was lower in flown monarchs relative to controls but increased with flight distance among flown monarchs; the other two immune measures showed no relationship to monarch flight. We also found that monarchs that were reproductively active were less efficient fliers, as they exerted more power during flight than monarchs in reproductive diapause. However, reproductive status did not modify relationships between flight and immune measures. Results of this study add to a growing body of work suggesting that migratory monarchs-like some other animals that travel vast distances-can complete their journeys with efficient use of resources and minimal costs.
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Affiliation(s)
| | - Vanessa O Ezenwa
- *Odum School of Ecology, University of Georgia, Athens, GA 30602, USA Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Sonia Altizer
- *Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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Henrichs B, Oosthuizen MC, Troskie M, Gorsich E, Gondhalekar C, Beechler BR, Ezenwa VO, Jolles AE. Within guild co-infections influence parasite community membership: a longitudinal study in African Buffalo. J Anim Ecol 2016; 85:1025-34. [PMID: 27084785 DOI: 10.1111/1365-2656.12535] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/04/2016] [Indexed: 11/26/2022]
Abstract
Experimental studies in laboratory settings have demonstrated a critical role of parasite interactions in shaping parasite communities. The sum of these interactions can produce diverse effects on individual hosts as well as influence disease emergence and persistence at the population level. A predictive framework for the effects of parasite interactions in the wild remains elusive, largely because of limited longitudinal or experimental data on parasite communities of free-ranging hosts. This 4-year study followed a community of haemoparasites in free-ranging African buffalo (Syncerus caffer). We detected infection by 11 haemoparasite species using PCR-based diagnostic techniques, and analyzed drivers of infection patterns using generalized linear mixed models to understand the role of host characteristics and season on infection likelihood. We tested for (i) effects of co-infection by other haemoparasites (within guild) and (ii) effects of parasites infecting different tissue types (across guild). We found that within guild co-infections were the strongest predictors of haemoparasite infections in the buffalo; but that seasonal and host characteristics also had important effects. In contrast, the evidence for across-guild effects of parasites utilizing different tissue on haemoparasite infection was weak. These results provide a nuanced view of the role of co-infections in determining haemoparasite infection patterns in free living mammalian hosts. Our findings suggest a role for interactions among parasites infecting a single tissue type in determining infection patterns.
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Affiliation(s)
- Brian Henrichs
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA
| | - Marinda C Oosthuizen
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Milana Troskie
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Sciences, University of Pretoria, Onderstepoort, 0110, South Africa
| | - Erin Gorsich
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Carmen Gondhalekar
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA
| | - Brianna R Beechler
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA.,Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
| | - Anna E Jolles
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA.,Department of Biomedical Sciences, Oregon State University, Corvallis, OR, 97331, USA
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Affiliation(s)
- Kimberly L. VanderWaal
- Department of Veterinary Population Medicine University of Minnesota 1365 Gortner Avenue St. Paul MN 55108 USA
| | - Vanessa O. Ezenwa
- Odum School of Ecology and Department of Infectious Diseases University of Georgia 140 East Green Street Athens GA 30602 USA
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Beechler BR, Manore CA, Reininghaus B, O'Neal D, Gorsich EE, Ezenwa VO, Jolles AE. Enemies and turncoats: bovine tuberculosis exposes pathogenic potential of Rift Valley fever virus in a common host, African buffalo (Syncerus caffer). Proc Biol Sci 2015; 282:rspb.2014.2942. [PMID: 25788592 DOI: 10.1098/rspb.2014.2942] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The ubiquity and importance of parasite co-infections in populations of free-living animals is beginning to be recognized, but few studies have demonstrated differential fitness effects of single infection versus co-infection in free-living populations. We investigated interactions between the emerging bacterial disease bovine tuberculosis (BTB) and the previously existing viral disease Rift Valley fever (RVF) in a competent reservoir host, African buffalo, combining data from a natural outbreak of RVF in captive buffalo at a buffalo breeding facility in 2008 with data collected from a neighbouring free-living herd of African buffalo in Kruger National Park. RVF infection was twice as likely in individual BTB+ buffalo as in BTB- buffalo, which, according to a mathematical model, may increase RVF outbreak size at the population level. In addition, co-infection was associated with a far higher rate of fetal abortion than other infection states. Immune interactions between BTB and RVF may underlie both of these interactions, since animals with BTB had decreased innate immunity and increased pro-inflammatory immune responses. This study is one of the first to demonstrate how the consequences of emerging infections extend beyond direct effects on host health, potentially altering the dynamics and fitness effects of infectious diseases that had previously existed in the ecosystem on free-ranging wildlife populations.
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Affiliation(s)
- B R Beechler
- College of Veterinary Medicine, Oregon State University, Dryden Hall, Corvallis, OR, USA
| | - C A Manore
- Center for Computational Science, Tulane University, Tulane, LA, USA
| | - B Reininghaus
- Mpumalanga State Veterinary Services, Nelspruit, Mpumalanga, South Africa
| | - D O'Neal
- Odum School of Ecology and Department of Infectious Disease, University of Georgia, Athens, GA, USA
| | - E E Gorsich
- Environmental Sciences, Oregon State University, OR, USA
| | - V O Ezenwa
- Odum School of Ecology and Department of Infectious Disease, University of Georgia, Athens, GA, USA
| | - A E Jolles
- College of Veterinary Medicine, Oregon State University, Dryden Hall, Corvallis, OR, USA
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48
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Young HS, Dirzo R, Helgen KM, McCauley DJ, Nunn CL, Snyder P, Veblen KE, Zhao S, Ezenwa VO. Large wildlife removal drives immune defence increases in rodents. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12542] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hillary S. Young
- University of California Santa Barbara Santa Barbara California 93106 USA
- Division of Mammals National Museum of Natural History Smithsonian Institution Washington District of Columbia 20013 USA
- Mpala Research Centre Box 555 Nanyuki Kenya
| | - Rodolfo Dirzo
- Department of Biology Stanford University Stanford California 94305 USA
| | - Kristofer M. Helgen
- Division of Mammals National Museum of Natural History Smithsonian Institution Washington District of Columbia 20013 USA
| | - Douglas J. McCauley
- University of California Santa Barbara Santa Barbara California 93106 USA
- Mpala Research Centre Box 555 Nanyuki Kenya
| | - Charles L. Nunn
- Department of Evolutionary Anthropology Duke University Durham North Carolina 27708 USA
- Duke Global Health Institute Duke University Durham North Carolina 27708 USA
| | - Paul Snyder
- Odum School of Ecology and Department of Infectious Diseases College of Veterinary Medicine University of Georgia Athens Georgia 30602 USA
- Department of Integrative Biology Oregon State University Corvallis Oregon 97331 USA
| | - Kari E. Veblen
- Mpala Research Centre Box 555 Nanyuki Kenya
- Department of Wildland Resources and Ecology Center Utah State University Logan Utah 84322 USA
| | - Serena Zhao
- Division of Mammals National Museum of Natural History Smithsonian Institution Washington District of Columbia 20013 USA
- Mpala Research Centre Box 555 Nanyuki Kenya
| | - Vanessa O. Ezenwa
- Mpala Research Centre Box 555 Nanyuki Kenya
- Odum School of Ecology and Department of Infectious Diseases College of Veterinary Medicine University of Georgia Athens Georgia 30602 USA
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49
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Budischak SA, Sakamoto K, Megow LC, Cummings KR, Urban JF, Ezenwa VO. Resource limitation alters the consequences of co-infection for both hosts and parasites. Int J Parasitol 2015; 45:455-63. [DOI: 10.1016/j.ijpara.2015.02.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 02/03/2015] [Accepted: 02/08/2015] [Indexed: 12/21/2022]
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50
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Gorsich EE, Ezenwa VO, Cross PC, Bengis RG, Jolles AE. Context-dependent survival, fecundity and predicted population-level consequences of brucellosis in African buffalo. J Anim Ecol 2015; 84:999-1009. [PMID: 25714466 DOI: 10.1111/1365-2656.12356] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 02/05/2015] [Indexed: 11/30/2022]
Abstract
Chronic infections may have negative impacts on wildlife populations, yet their effects are difficult to detect in the absence of long-term population monitoring. Brucella abortus, the bacteria responsible for bovine brucellosis, causes chronic infections and abortions in wild and domestic ungulates, but its impact on population dynamics is not well understood. We report infection patterns and fitness correlates of bovine brucellosis in African buffalo based on (1) 7 years of cross-sectional disease surveys and (2) a 4-year longitudinal study in Kruger National Park (KNP), South Africa. We then used a matrix population model to translate these observed patterns into predicted population-level effects. Annual brucellosis seroprevalence ranged from 8·7% (95% CI = 1·8-15·6) to 47·6% (95% CI = 35·1-60·1) increased with age until adulthood (>6) and varied by location within KNP. Animals were on average in worse condition after testing positive for brucellosis (F = -5·074, P < 0·0001), and infection was associated with a 2·0 (95% CI = 1·1-3·7) fold increase in mortality (χ(2) = 2·039, P = 0·036). Buffalo in low body condition were associated with lower reproductive success (F = 2·683, P = 0·034), but there was no association between brucellosis and pregnancy or being observed with a calf. For the range of body condition scores observed in the population, the model-predicted growth rate was λ = 1·11 (95% CI = 1·02-1·21) in herds without brucellosis and λ = 1·00 (95% CI = 0·85-1·16) when brucellosis seroprevalence was 30%. Our results suggest that brucellosis infection can potentially result in reduced population growth rates, but because these effects varied with demographic and environmental conditions, they may remain unseen without intensive, longitudinal monitoring.
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Affiliation(s)
- Erin E Gorsich
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA
| | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Paul C Cross
- U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, MT, 59715, USA
| | - Roy G Bengis
- Department of Agriculture, Forestry and Fisheries, Directorate of Animal Health, State Veterinary Office, Skukuza, 1350, South Africa
| | - Anna E Jolles
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR, 97331, USA
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