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de Freitas Costa E, Streng K, Avelino de Souza Santos M, Counotte MJ. The effect of temperature on the boundary conditions of West Nile virus circulation in Europe. PLoS Negl Trop Dis 2024; 18:e0012162. [PMID: 38709836 PMCID: PMC11098507 DOI: 10.1371/journal.pntd.0012162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 05/16/2024] [Accepted: 04/22/2024] [Indexed: 05/08/2024] Open
Abstract
West Nile virus (WNV) is a vector-borne flavivirus that causes an increasing number of human and equine West Nile fever cases in Europe. While the virus has been present in the Mediterranean basin and the Balkans since the 1960s, recent years have witnessed its northward expansion, with the first human cases reported in Germany in 2018 and the Netherlands in 2020. WNV transmission and amplification within mosquitoes are temperature-dependent. This study applies a mathematical modelling approach to assess the conditions under which WNV circulation occurs based on the proportion of mosquito bites on WNV-competent birds (dilution), vector-host ratios, mosquito season length and the observed daily temperature data. We modelled five distinct European regions where previous WNV circulation has been observed within the Netherlands, Germany, Spain, Italy, and Greece. We observed that the number of days in which the basic reproduction number (R0) is above one, increased over the last 40 years in all five regions. In the Netherlands, the number of days in which the R0 is above one, is 70% lower than in Spain. The temperature in Greece, Spain and Italy allowed for circulation under low vector-host ratios, and at a high dilution. On the other hand in the Netherlands and Germany, given the observed daily temperature, the thresholds for circulation requires a lower dilution and higher vector-host ratios. For the Netherlands, a short window of introductions between late May and mid-June would result in detectable outbreaks. Our findings revealed that the temperate maritime climate of the Netherlands allows WNV circulation primarily during warmer summers, and only under high vector-host ratios. This research contributes valuable insights into the dynamic relationship between temperature, vector properties, and WNV transmission, offering guidance for proactive strategies in addressing this emerging health threat in Europe.
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Affiliation(s)
- Eduardo de Freitas Costa
- Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, the Netherlands
| | - Kiki Streng
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, the Netherlands
| | | | - Michel Jacques Counotte
- Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, the Netherlands
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Holcomb KM, Staples JE, Nett RJ, Beard CB, Petersen LR, Benjamin SG, Green BW, Jones H, Johansson MA. Multi-Model Prediction of West Nile Virus Neuroinvasive Disease With Machine Learning for Identification of Important Regional Climatic Drivers. Geohealth 2023; 7:e2023GH000906. [PMID: 38023388 PMCID: PMC10654557 DOI: 10.1029/2023gh000906] [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] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/15/2023] [Accepted: 10/21/2023] [Indexed: 12/01/2023]
Abstract
West Nile virus (WNV) is the leading cause of mosquito-borne illness in the continental United States (CONUS). Spatial heterogeneity in historical incidence, environmental factors, and complex ecology make prediction of spatiotemporal variation in WNV transmission challenging. Machine learning provides promising tools for identification of important variables in such situations. To predict annual WNV neuroinvasive disease (WNND) cases in CONUS (2015-2021), we fitted 10 probabilistic models with variation in complexity from naïve to machine learning algorithm and an ensemble. We made predictions in each of nine climate regions on a hexagonal grid and evaluated each model's predictive accuracy. Using the machine learning models (random forest and neural network), we identified the relative importance and variation in ranking of predictors (historical WNND cases, climate anomalies, human demographics, and land use) across regions. We found that historical WNND cases and population density were among the most important factors while anomalies in temperature and precipitation often had relatively low importance. While the relative performance of each model varied across climatic regions, the magnitude of difference between models was small. All models except the naïve model had non-significant differences in performance relative to the baseline model (negative binomial model fit per hexagon). No model, including the ensemble or more complex machine learning models, outperformed models based on historical case counts on the hexagon or region level; these models are good forecasting benchmarks. Further work is needed to assess if predictive capacity can be improved beyond that of these historical baselines.
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Affiliation(s)
- Karen M. Holcomb
- Global Systems LaboratoryNational Oceanic and Atmospheric AdministrationBoulderCOUSA
- Now at Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionFort CollinsCOUSA
| | - J. Erin Staples
- Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionFort CollinsCOUSA
| | - Randall J. Nett
- Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionFort CollinsCOUSA
| | - Charles B. Beard
- Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionFort CollinsCOUSA
| | - Lyle R. Petersen
- Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionFort CollinsCOUSA
| | - Stanley G. Benjamin
- Global Systems LaboratoryNational Oceanic and Atmospheric AdministrationBoulderCOUSA
- Cooperative Institute for Research in Environmental SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - Benjamin W. Green
- Global Systems LaboratoryNational Oceanic and Atmospheric AdministrationBoulderCOUSA
- Cooperative Institute for Research in Environmental SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - Hunter Jones
- Climate Prediction OfficeNational Oceanic and Atmospheric AdministrationSilver SpringMDUSA
| | - Michael A. Johansson
- Division of Vector‐Borne DiseasesCenters for Disease Control and PreventionSan JuanPRUSA
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Holcomb KM, Nguyen C, Komar N, Foy BD, Panella NA, Baskett ML, Barker CM. Predicted reduction in transmission from deployment of ivermectin-treated birdfeeders for local control of West Nile virus. Epidemics 2023; 44:100697. [PMID: 37348378 PMCID: PMC10529638 DOI: 10.1016/j.epidem.2023.100697] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 05/01/2023] [Accepted: 06/12/2023] [Indexed: 06/24/2023] Open
Abstract
Ivermectin (IVM)-treated birds provide the potential for targeted control of Culex mosquitoes to reduce West Nile virus (WNV) transmission. Ingestion of IVM increases mosquito mortality, which could reduce WNV transmission from birds to humans and in enzootic maintenance cycles affecting predominantly bird-feeding mosquitoes and from birds to humans. This strategy might also provide an alternative method for WNV control that is less hampered by insecticide resistance and the logistics of large-scale pesticide applications. Through a combination of field studies and modeling, we assessed the feasibility and impact of deploying IVM-treated birdfeed in residential neighborhoods to reduce WNV transmission. We first tracked 105 birds using radio telemetry and radio frequency identification to monitor their feeder usage and locations of nocturnal roosts in relation to five feeder sites in a neighborhood in Fort Collins, Colorado. Using these results, we then modified a compartmental model of WNV transmission to account for the impact of IVM on mosquito mortality and spatial movement of birds and mosquitoes on the neighborhood level. We found that, while the number of treated lots in a neighborhood strongly influenced the total transmission potential, the arrangement of treated lots in a neighborhood had little effect. Increasing the proportion of treated birds, regardless of the WNV competency status, resulted in a larger reduction in infection dynamics than only treating competent birds. Taken together, model results indicate that deployment of IVM-treated feeders could reduce local transmission throughout the WNV season, including reducing the enzootic transmission prior to the onset of human infections, with high spatial coverage and rates of IVM-induced mortality in mosquitoes. To improve predictions, more work is needed to refine estimates of daily mosquito movement in urban areas and rates of IVM-induced mortality. Our results can guide future field trials of this control strategy.
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Affiliation(s)
- Karen M Holcomb
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, United States.
| | - Chilinh Nguyen
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States; Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States
| | - Nicholas Komar
- Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States
| | - Brian D Foy
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Nicholas A Panella
- Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States
| | - Marissa L Baskett
- Department of Environmental Science and Policy, University of California, Davis, CA, United States
| | - Christopher M Barker
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, United States.
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Gorris ME, Randerson JT, Coffield SR, Treseder KK, Zender CS, Xu C, Manore CA. Assessing the Influence of Climate on the Spatial Pattern of West Nile Virus Incidence in the United States. Environ Health Perspect 2023; 131:47016. [PMID: 37104243 PMCID: PMC10137712 DOI: 10.1289/ehp10986] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
BACKGROUND West Nile virus (WNV) is the leading cause of mosquito-borne disease in humans in the United States. Since the introduction of the disease in 1999, incidence levels have stabilized in many regions, allowing for analysis of climate conditions that shape the spatial structure of disease incidence. OBJECTIVES Our goal was to identify the seasonal climate variables that influence the spatial extent and magnitude of WNV incidence in humans. METHODS We developed a predictive model of contemporary mean annual WNV incidence using U.S. county-level case reports from 2005 to 2019 and seasonally averaged climate variables. We used a random forest model that had an out-of-sample model performance of R2=0.61. RESULTS Our model accurately captured the V-shaped area of higher WNV incidence that extends from states on the Canadian border south through the middle of the Great Plains. It also captured a region of moderate WNV incidence in the southern Mississippi Valley. The highest levels of WNV incidence were in regions with dry and cold winters and wet and mild summers. The random forest model classified counties with average winter precipitation levels <23.3mm/month as having incidence levels over 11 times greater than those of counties that are wetter. Among the climate predictors, winter precipitation, fall precipitation, and winter temperature were the three most important predictive variables. DISCUSSION We consider which aspects of the WNV transmission cycle climate conditions may benefit the most and argued that dry and cold winters are climate conditions optimal for the mosquito species key to amplifying WNV transmission. Our statistical model may be useful in projecting shifts in WNV risk in response to climate change. https://doi.org/10.1289/EHP10986.
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Affiliation(s)
- Morgan E. Gorris
- Information Systems and Modeling, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - James T. Randerson
- Department of Earth System Science, University of California, Irvine, Irvine, California, USA
| | - Shane R. Coffield
- Department of Earth System Science, University of California, Irvine, Irvine, California, USA
| | - Kathleen K. Treseder
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, USA
| | - Charles S. Zender
- Department of Earth System Science, University of California, Irvine, Irvine, California, USA
| | - Chonggang Xu
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Carrie A. Manore
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
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Benzarti E, Murray KO, Ronca SE. Interleukins, Chemokines, and Tumor Necrosis Factor Superfamily Ligands in the Pathogenesis of West Nile Virus Infection. Viruses 2023; 15:v15030806. [PMID: 36992514 PMCID: PMC10053297 DOI: 10.3390/v15030806] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [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: 02/28/2023] [Revised: 03/15/2023] [Accepted: 03/17/2023] [Indexed: 03/31/2023] Open
Abstract
West Nile virus (WNV) is a mosquito-borne pathogen that can lead to encephalitis and death in susceptible hosts. Cytokines play a critical role in inflammation and immunity in response to WNV infection. Murine models provide evidence that some cytokines offer protection against acute WNV infection and assist with viral clearance, while others play a multifaceted role WNV neuropathogenesis and immune-mediated tissue damage. This article aims to provide an up-to-date review of cytokine expression patterns in human and experimental animal models of WNV infections. Here, we outline the interleukins, chemokines, and tumor necrosis factor superfamily ligands associated with WNV infection and pathogenesis and describe the complex roles they play in mediating both protection and pathology of the central nervous system during or after virus clearance. By understanding of the role of these cytokines during WNV neuroinvasive infection, we can develop treatment options aimed at modulating these immune molecules in order to reduce neuroinflammation and improve patient outcomes.
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Affiliation(s)
- Emna Benzarti
- Department of Pediatrics, Division of Tropical Medicine, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
| | - Kristy O Murray
- Department of Pediatrics, Division of Tropical Medicine, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Immunology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shannon E Ronca
- Department of Pediatrics, Division of Tropical Medicine, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Immunology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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6
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Holcomb KM, Mathis S, Staples JE, Fischer M, Barker CM, Beard CB, Nett RJ, Keyel AC, Marcantonio M, Childs ML, Gorris ME, Rochlin I, Hamins-Puértolas M, Ray EL, Uelmen JA, DeFelice N, Freedman AS, Hollingsworth BD, Das P, Osthus D, Humphreys JM, Nova N, Mordecai EA, Cohnstaedt LW, Kirk D, Kramer LD, Harris MJ, Kain MP, Reed EMX, Johansson MA. Evaluation of an open forecasting challenge to assess skill of West Nile virus neuroinvasive disease prediction. Parasit Vectors 2023; 16:11. [PMID: 36635782 PMCID: PMC9834680 DOI: 10.1186/s13071-022-05630-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND West Nile virus (WNV) is the leading cause of mosquito-borne illness in the continental USA. WNV occurrence has high spatiotemporal variation, and current approaches to targeted control of the virus are limited, making forecasting a public health priority. However, little research has been done to compare strengths and weaknesses of WNV disease forecasting approaches on the national scale. We used forecasts submitted to the 2020 WNV Forecasting Challenge, an open challenge organized by the Centers for Disease Control and Prevention, to assess the status of WNV neuroinvasive disease (WNND) prediction and identify avenues for improvement. METHODS We performed a multi-model comparative assessment of probabilistic forecasts submitted by 15 teams for annual WNND cases in US counties for 2020 and assessed forecast accuracy, calibration, and discriminatory power. In the evaluation, we included forecasts produced by comparison models of varying complexity as benchmarks of forecast performance. We also used regression analysis to identify modeling approaches and contextual factors that were associated with forecast skill. RESULTS Simple models based on historical WNND cases generally scored better than more complex models and combined higher discriminatory power with better calibration of uncertainty. Forecast skill improved across updated forecast submissions submitted during the 2020 season. Among models using additional data, inclusion of climate or human demographic data was associated with higher skill, while inclusion of mosquito or land use data was associated with lower skill. We also identified population size, extreme minimum winter temperature, and interannual variation in WNND cases as county-level characteristics associated with variation in forecast skill. CONCLUSIONS Historical WNND cases were strong predictors of future cases with minimal increase in skill achieved by models that included other factors. Although opportunities might exist to specifically improve predictions for areas with large populations and low or high winter temperatures, areas with high case-count variability are intrinsically more difficult to predict. Also, the prediction of outbreaks, which are outliers relative to typical case numbers, remains difficult. Further improvements to prediction could be obtained with improved calibration of forecast uncertainty and access to real-time data streams (e.g. current weather and preliminary human cases).
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Affiliation(s)
- Karen M. Holcomb
- Global Systems Laboratory, National Atmospheric and Oceanic Administration, Boulder, CO USA
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - Sarabeth Mathis
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - J. Erin Staples
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - Marc Fischer
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - Christopher M. Barker
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA USA
| | - Charles B. Beard
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - Randall J. Nett
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO USA
| | - Alexander C. Keyel
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY USA
- Department of Atmospheric and Environmental Sciences, University at Albany, Albany, NY USA
| | - Matteo Marcantonio
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA USA
- Evolutionary Ecology and Genetics Group, Earth & Life Institute-UCLouvain, Louvain-La-Neuve, Belgium
| | - Marissa L. Childs
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, CA USA
| | - Morgan E. Gorris
- Information Systems and Modeling, Los Alamos National Laboratory, Los Alamos, NM USA
| | - Ilia Rochlin
- Center for Vector Biology, Rutgers University, New Brunswick, NJ USA
| | | | - Evan L. Ray
- Department of Mathematics and Statistics, Mount Holyoke College, South Hadley, MA USA
| | - Johnny A. Uelmen
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL USA
| | - Nicholas DeFelice
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Department of Global Health, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Andrew S. Freedman
- Biomathematics Graduate Program, North Carolina State University, Raleigh, NC USA
| | | | - Praachi Das
- Biomathematics Graduate Program, North Carolina State University, Raleigh, NC USA
| | - Dave Osthus
- Statistical Sciences Group, Los Alamos National Laboratory, Los Alamos, NM USA
| | - John M. Humphreys
- Agricultural Research Service, United States Department of Agriculture, Sidney, MT USA
| | - Nicole Nova
- Department of Biology, Stanford University, Stanford, CA USA
| | | | - Lee W. Cohnstaedt
- National Bio- and Agro-Defense Facility, Agricultural Research Service, United States Department of Agriculture, Manhattan, KS USA
| | - Devin Kirk
- Department of Biology, Stanford University, Stanford, CA USA
| | - Laura D. Kramer
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY USA
| | | | - Morgan P. Kain
- Department of Biology, Stanford University, Stanford, CA USA
| | - Emily M. X. Reed
- Invasive Species Working Group, Global Change Center, Fralin Life Sciences Institute, Virginia Tech, Blacksburg, NC USA
| | - Michael A. Johansson
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, PR USA
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Affiliation(s)
- Melanie R. Kunkel
- Southeastern Cooperative Wildlife Disease Study University of Georgia 589 D.W. Brooks Drive Athens 30602 GA USA
| | - Daniel G. Mead
- Southeastern Cooperative Wildlife Disease Study University of Georgia 589 D.W. Brooks Drive Athens 30602 GA USA
| | - Mark G. Ruder
- Southeastern Cooperative Wildlife Disease Study University of Georgia 589 D.W. Brooks Drive Athens 30602 GA USA
| | - Nicole M. Nemeth
- Southeastern Cooperative Wildlife Disease Study University of Georgia 589 D.W. Brooks Drive Athens 30602 GA USA
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Holcomb KM, Nguyen C, Foy BD, Ahn M, Cramer K, Lonstrup ET, Mete A, Tell LA, Barker CM. Effects of ivermectin treatment of backyard chickens on mosquito dynamics and West Nile virus transmission. PLoS Negl Trop Dis 2022; 16:e0010260. [PMID: 35333866 PMCID: PMC9012369 DOI: 10.1371/journal.pntd.0010260] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 08/03/2021] [Revised: 04/15/2022] [Accepted: 02/14/2022] [Indexed: 11/18/2022] Open
Abstract
Background Vector control strategies typically rely on pesticides to target mosquitoes involved in enzootic and zoonotic transmission of West Nile virus (WNV). Nevertheless, increasing insecticide resistance and a desire to reduce pesticide usage provide the impetus for developing alternative strategies. Ivermectin (IVM), an antiparasitic drug which is widely used in human and veterinary medicine, is a potential alternative for targeted control because Culex mosquitoes experience increased mortality following ingestion of IVM in bloodmeals. Methodology/Principal findings We conducted a randomized field trial to investigate the impact of treating backyard chicken flocks with IVM in urban neighborhoods across Davis, California on mosquito populations and WNV transmission dynamics. We observed a significant reduction in WNV seroconversions in treated vs. untreated chickens, suggesting a reduction in WNV transmission intensity around treated flocks. We also detected a reduction in parity rates of Cx. tarsalis near treated vs. untreated flocks and increased mortality in wild mosquitoes following a bloodmeal on treated chickens (IVM serum concentration > 5ng/mL) vs. chickens with IVM serum concentrations < 5 ng/mL. However, we did not find a significant difference in abundance or infection prevalence in mosquitoes between treatment groups associated with the reductions in seroconversions. Mosquito immigration from surrounding larval habitat, relatively low WNV activity in the study area, and variable IVM serum concentrations likely contributed to uncertainty about the impact. Conclusions/Significance Taken together, our results point to a reduction in WNV transmission due to the impact of IVM on Culex mosquito populations and support the ongoing investigation of oral administration of IVM to wild birds for local control of WNV transmission, although further work is needed to optimize dosing and understand effects on entomological endpoints. Current mosquito control strategies aimed to prevent pathogen transmission to humans have limited ability to target mosquitoes involved in amplification and spillover transmission of pathogens like West Nile virus (WNV). Additionally, growing prevalence of insecticide resistance in mosquito populations limit the efficacy of these insecticide-based control strategies. Ivermectin (IVM) provides an alternative avenue for control by increasing the mortality of mosquitoes that ingest this drug in bloodmeals. Therefore, IVM treatment of avian species that account for the majority of mosquito bloodmeals during the WNV transmission season could be an effective control strategy. Building on pilot studies indicating the efficacy and feasibility of IVM-deployment for WNV control, we performed a randomized field trial to investigate the impact of IVM-treatment of backyard chickens on local population dynamics of Culex mosquitoes and WNV transmission. We were able to link changes in mosquito populations to reduction in WNV transmission, as measured by chicken seroconversions, through IVM-induced mortality in mosquitoes. However, further work is needed to identify the impact of treatment on mosquito abundance and infection prevalence to fully attribute observed changes to IVM administration. Overall, our results support IVM treatment as a potentially effective alternative to insecticide-based vector control strategies and one that can be used to target WNV transmission on the local scale.
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Affiliation(s)
- Karen M. Holcomb
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Chilinh Nguyen
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Brian D. Foy
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Michelle Ahn
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Kurt Cramer
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Emma T. Lonstrup
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Asli Mete
- California Animal Health and Food Safety Lab, Department of Pathology, Microbiology & Immunology, University of California, Davis, California, United States of America
| | - Lisa A. Tell
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Christopher M. Barker
- Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
- * E-mail:
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Roy CL, Carstensen M, LaSharr K, Humpal C, Dick T, Kunkel M, Nemeth NM. WEST NILE VIRUS EXPOSURE AND INFECTION AMONG HUNTER-HARVESTED RUFFED GROUSE COHORTS IN A STABLE POPULATION. J Wildl Dis 2021. [PMID: 34780646 DOI: 10.7589/JWD-D-21-00018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 07/29/2021] [Indexed: 11/20/2022]
Abstract
West Nile virus (WNV) was introduced to North America two decades ago, but for many species, including Ruffed Grouse (Bonasa umbellus), the effects of WNV on individuals and populations remain poorly understood. Recent studies suggest the effect of WNV on Ruffed Grouse might vary among geographic regions, depending on habitat conditions. We studied WNV in Minnesota, US, during 2018-19, in a region known to have abundant Ruffed Grouse habitat and a population cycling around a stable long-term average. We worked with cooperating hunters to collect hearts, feathers, and blood on filter strips from birds harvested in the fall to examine exposure to the virus. We detected antibodies to WNV or a flavivirus (probably WNV) in 12.5% and 12.3% of birds in 2018 and 2019, respectively. However, we did not isolate the virus from any heart samples, indicating that exposed birds were not experiencing an active infection of WNV at the time of harvest. Our findings indicate that, although Minnesota Ruffed Grouse are exposed to WNV, some birds mount a successful immune response and survive. However, our sampling approach did not account for birds that might have become infected over the summer and died, so it is unknown how much WNV mortality occurred before the fall harvest. Birds lost to WNV over the summer could reduce the number of birds that hunters see in the fall, thus reducing the quality of their hunting experiences. Management options for mitigating WNV impacts and other stressors consist primarily of providing high-quality Ruffed Grouse habitat that produces birds in good condition that are more likely to recover from infection.
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Kuchinsky SC, Frere F, Heitzman-Breen N, Golden J, Vázquez A, Honaker CF, Siegel PB, Ciupe SM, LeRoith T, Duggal NK. Pathogenesis and shedding of Usutu virus in juvenile chickens. Emerg Microbes Infect 2021; 10:725-738. [PMID: 33769213 PMCID: PMC8043533 DOI: 10.1080/22221751.2021.1908850] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 10/25/2022]
Abstract
Usutu virus (USUV; family: Flaviviridae, genus: Flavivirus), is an emerging zoonotic arbovirus that causes severe neuroinvasive disease in humans and has been implicated in the loss of breeding bird populations in Europe. USUV is maintained in an enzootic cycle between ornithophilic mosquitos and wild birds. As a member of the Japanese encephalitis serocomplex, USUV is closely related to West Nile virus (WNV) and St. Louis encephalitis virus (SLEV), both neuroinvasive arboviruses endemic in wild bird populations in the United States. An avian model for USUV is essential to understanding zoonotic transmission. Here we describe the first avian models of USUV infection with the development of viremia. Juvenile commercial ISA Brown chickens were susceptible to infection by multiple USUV strains with evidence of cardiac lesions. Juvenile chickens from two chicken lines selected for high (HAS) or low (LAS) antibody production against sheep red blood cells showed markedly different responses to USUV infection. Morbidity and mortality were observed in the LAS chickens, but not HAS chickens. LAS chickens had significantly higher viral titers in blood and other tissues, as well as oral secretions, and significantly lower development of neutralizing antibody responses compared to HAS chickens. Mathematical modelling of virus-host interactions showed that the viral clearance rate is a stronger mitigating factor for USUV viremia than neutralizing antibody response in this avian model. These chicken models provide a tool for further understanding USUV pathogenesis in birds and evaluating transmission dynamics between avian hosts and mosquito vectors.
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Affiliation(s)
- Sarah C Kuchinsky
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Francesca Frere
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Nora Heitzman-Breen
- Department of Mathematics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Jacob Golden
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Ana Vázquez
- National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Epidemiology and Public Health Network of Biomedical Research Centre (CIBERESP), Madrid, Spain
| | - Christa F Honaker
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Paul B Siegel
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Stanca M Ciupe
- Department of Mathematics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Tanya LeRoith
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Nisha K Duggal
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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11
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Giglia G, Agliani G, Munnink BBO, Sikkema RS, Mandara MT, Lepri E, Kik M, Ijzer J, Rijks JM, Fast C, Koopmans MPG, Verheije MH, Gröne A, Reusken CBEM, van den Brand JMA. Pathology and Pathogenesis of Eurasian Blackbirds ( Turdus merula) Naturally Infected with Usutu Virus. Viruses 2021; 13:1481. [PMID: 34452347 PMCID: PMC8402641 DOI: 10.3390/v13081481] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [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: 06/07/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 01/13/2023] Open
Abstract
The Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus. Despite its continuous circulation in Europe, knowledge on the pathology, cellular and tissue tropism and pathogenetic potential of different circulating viral lineages is still fragmentary. Here, macroscopic and microscopic evaluations are performed in association with the study of cell and tissue tropism and comparison of lesion severity of two circulating virus lineages (Europe 3; Africa 3) in 160 Eurasian blackbirds (Turdus merula) in the Netherlands. Results confirm hepatosplenomegaly, coagulative necrosis and lymphoplasmacytic inflammation as major patterns of lesions and, for the first time, vasculitis as a novel virus-associated lesion. A USUV and Plasmodium spp. co-infection was commonly identified. The virus was associated with lesions by immunohistochemistry and was reported most commonly in endothelial cells and blood circulating and tissue mononucleated cells, suggesting them as a major route of entry and spread. A tropism for mononuclear phagocytes cells was further supported by viral labeling in multinucleated giant cells. The involvement of ganglionic neurons and epithelial cells of the gastrointestinal tract suggests a possible role of oral transmission, while the involvement of feather follicle shafts and bulbs suggests their use as a diagnostic sample for live bird testing. Finally, results suggest similar pathogenicity for the two circulating lineages.
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Affiliation(s)
- Giuseppe Giglia
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (M.T.M.); (E.L.)
| | - Gianfilippo Agliani
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
| | - Bas B. Oude Munnink
- Department of Viroscience, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands; (B.B.O.M.); (R.S.S.); (M.P.G.K.); (C.B.E.M.R.)
| | - Reina S. Sikkema
- Department of Viroscience, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands; (B.B.O.M.); (R.S.S.); (M.P.G.K.); (C.B.E.M.R.)
| | - Maria Teresa Mandara
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (M.T.M.); (E.L.)
| | - Elvio Lepri
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (M.T.M.); (E.L.)
| | - Marja Kik
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands;
| | - Jooske Ijzer
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands;
| | - Jolianne M. Rijks
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands;
| | - Christine Fast
- Institute of Novel and Emerging Infectious Disease, Friedrich-Loeffler Institut, D-17493 Isle of Riems, Germany;
| | - Marion P. G. Koopmans
- Department of Viroscience, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands; (B.B.O.M.); (R.S.S.); (M.P.G.K.); (C.B.E.M.R.)
| | - Monique H. Verheije
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
| | - Andrea Gröne
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands;
| | - Chantal B. E. M. Reusken
- Department of Viroscience, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands; (B.B.O.M.); (R.S.S.); (M.P.G.K.); (C.B.E.M.R.)
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, 3720 BA Bilthoven, The Netherlands
| | - Judith M. A. van den Brand
- Division of Pathology, Department of Biomedical Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (G.G.); (G.A.); (M.K.); (J.I.); (M.H.V.); (A.G.)
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands;
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12
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Holcomb KM, Reiner RC, Barker CM. Spatio-temporal impacts of aerial adulticide applications on populations of West Nile virus vector mosquitoes. Parasit Vectors 2021; 14:120. [PMID: 33627165 PMCID: PMC7905633 DOI: 10.1186/s13071-021-04616-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 10/12/2020] [Accepted: 01/29/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Aerial applications of insecticides that target adult mosquitoes are widely used to reduce transmission of West Nile virus to humans during periods of epidemic risk. However, estimates of the reduction in abundance following these treatments typically focus on single events, rely on pre-defined, untreated control sites and can vary widely due to stochastic variation in population dynamics and trapping success unrelated to the treatment. METHODS To overcome these limitations, we developed generalized additive models fitted to mosquito surveillance data collected from CO2-baited traps in Sacramento and Yolo counties, California from 2006 to 2017. The models accounted for the expected spatial and temporal trends in the abundance of adult female Culex (Cx.) tarsalis and Cx. pipiens in the absence of aerial spraying. Estimates for the magnitude of deviation from baseline abundance following aerial spray events were obtained from the models. RESULTS At 1-week post-treatment with full spatial coverage of the trapping area by pyrethroid or pyrethrin products, Cx. pipiens abundance was reduced by a mean of 52.4% (95% confidence intrval [CI] - 65.6, - 36.5%) while the use of at least one organophosphate pesticide resulted in a mean reduction of 76.2% (95% CI - 82.8, - 67.9%). For Cx. tarsalis, at 1-week post-treatment with full coverage there was a reduction in abundance of 30.7% (95% CI - 54.5, 2.5%). Pesticide class was not a significant factor contributing to the reduction. In comparison, repetition of spraying over three to four consecutive weeks resulted in similar estimates for Cx. pipiens and estimates of somewhat smaller magnitude for Cx. tarsalis. CONCLUSIONS Aerial adulticides are effective for achieving a rapid short-term reduction of the abundance of the primary West Nile virus vectors, Cx. tarsalis and Cx. pipiens. A larger magnitude of reduction was estimated in Cx. pipiens, possibly due to the species' focal distribution. Effects of aerial sprays on Cx. tarsalis populations are likely modulated by the species' large dispersal ability, population sizes and vast productive larval habitat present in the study area. Our modeling approach provides a new way to estimate effects of public health pesticides on vector populations using routinely collected observational data and accounting for spatio-temporal trends and contextual factors like weather and habitat. This approach does not require pre-selected control sites and expands upon past studies that have focused on the effects of individual aerial treatment events.
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Affiliation(s)
- Karen M Holcomb
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
| | - Robert C Reiner
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - Christopher M Barker
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
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13
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Pérez-Ramírez E, Cano-Gómez C, Llorente F, Vodica A, Veljović L, Toklikishvilli N, Sherifi K, Sghaier S, Omani A, Kustura A, Krstevski K, Karayel-Hacioglu I, Hagag NM, El Hage J, Davdyan H, Bintarif MS, Adzic B, Abouchoaib N, Jiménez-Clavero MÁ, Fernández-Pinero J. Evaluation of West Nile Virus Diagnostic Capacities in Veterinary Laboratories of the Mediterranean and Black Sea Regions. Pathogens 2020; 9:E1038. [PMID: 33322276 DOI: 10.3390/pathogens9121038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 01/18/2023] Open
Abstract
The increasing incidence of West Nile virus (WNV) in the Euro-Mediterranean area warrants the implementation of effective surveillance programs in animals. A crucial step in the fight against the disease is the evaluation of the capacity of the veterinary labs to accurately detect the infection in animal populations. In this context, the animal virology network of the MediLabSecure project organized an external quality assessment (EQA) to evaluate the WNV molecular and serological diagnostic capacities of beneficiary veterinary labs. Laboratories from 17 Mediterranean and Black Sea countries participated. The results of the triplex real time RT-PCR for simultaneous detection and differentiation of WNV lineage 1 (L1), lineage 2 (L2) and Usutu virus (USUV) were highly satisfactory, especially for L1 and L2, with detection rates of 97.9% and 100%, respectively. For USUV, 75% of the labs reported correct results. More limitations were observed for the generic detection of flaviviruses using conventional reverse-transcription polymerase chain reaction (RT-PCR), since only 46.1% reported correct results in the whole panel. As regards the serological panel, the results were excellent for the generic detection of WNV antibodies. More variability was observed for the specific detection of IgM antibodies with a higher percentage of incorrect results mainly in samples with low titers. This EQA provides a good overview of the WNV (and USUV) diagnostic performance of the involved veterinary labs and demonstrates that the implemented training program was successful in upgrading their diagnostic capacities.
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14
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Vet LJ, Setoh YX, Amarilla AA, Habarugira G, Suen WW, Newton ND, Harrison JJ, Hobson-Peters J, Hall RA, Bielefeldt-Ohmann H. Protective Efficacy of a Chimeric Insect-Specific Flavivirus Vaccine against West Nile Virus. Vaccines (Basel) 2020; 8:vaccines8020258. [PMID: 32485930 PMCID: PMC7349994 DOI: 10.3390/vaccines8020258] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [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: 04/28/2020] [Revised: 05/25/2020] [Accepted: 05/27/2020] [Indexed: 12/01/2022] Open
Abstract
Virulent strains of West Nile virus (WNV) are highly neuro-invasive and human infection is potentially lethal. However, no vaccine is currently available for human use. Here, we report the immunogenicity and protective efficacy of a vaccine derived from a chimeric virus, which was constructed using the structural proteins (prM and E) of the Kunjin strain of WNV (WNVKUN) and the genome backbone of the insect-specific flavivirus Binjari virus (BinJV). This chimeric virus (BinJ/WNVKUN-prME) exhibits an insect-specific phenotype and does not replicate in vertebrate cells. Importantly, it authentically presents the prM-E proteins of WNVKUN, which is antigenically very similar to other WNV strains and lineages. Therefore BinJ/WNVKUN-prME represents an excellent candidate to assess as a vaccine against virulent WNV strains, including the highly pathogenic WNVNY99. When CD1 mice were immunized with purified BinJ/WNVKUN-prME, they developed robust neutralizing antibody responses after a single unadjuvanted dose of 1 to 5 μg. We further demonstrated complete protection against viremia and mortality after lethal challenge with WNVNY99, with no clinical or subclinical pathology observed in vaccinated animals. These data suggest that BinJ/WNVKUN-prME represents a safe and effective WNV vaccine candidate that warrants further investigation for use in humans or in veterinary applications.
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Affiliation(s)
- Laura J. Vet
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Yin Xiang Setoh
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Alberto A. Amarilla
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Gervais Habarugira
- School of Veterinary Science, University of Queensland Gatton Campus, Queensland 4343, Australia;
| | - Willy W. Suen
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Natalee D. Newton
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Jessica J. Harrison
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
| | - Jody Hobson-Peters
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
- Australian Infectious Diseases Research Centre, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Roy A. Hall
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
- Australian Infectious Diseases Research Centre, University of Queensland, St Lucia, Queensland 4072, Australia
- Correspondence: (R.A.H.); (H.B.-O.)
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia; (L.J.V.); (Y.X.S.); (A.A.A.); (W.W.S.); (N.D.N.); (J.J.H.); (J.H.-P.)
- School of Veterinary Science, University of Queensland Gatton Campus, Queensland 4343, Australia;
- Australian Infectious Diseases Research Centre, University of Queensland, St Lucia, Queensland 4072, Australia
- Correspondence: (R.A.H.); (H.B.-O.)
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15
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Chevalier V, Marsot M, Molia S, Rasamoelina H, Rakotondravao R, Pedrono M, Lowenski S, Durand B, Lecollinet S, Beck C. Serological Evidence of West Nile and Usutu Viruses Circulation in Domestic and Wild Birds in Wetlands of Mali and Madagascar in 2008. Int J Environ Res Public Health 2020; 17:ijerph17061998. [PMID: 32197367 PMCID: PMC7142923 DOI: 10.3390/ijerph17061998] [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] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 11/30/2022]
Abstract
The geographical distribution and impact on animal and human health of both West Nile and Usutu viruses, two flaviviruses of the Japanese encephalitis complex, have been increasing during the past two decades. Both viruses circulate in Europe and Africa within a natural cycle between wild birds and mosquitoes, mainly from the Culex genus. We retrospectively analyzed sera from domestic and wild birds sampled in 2008 in two wetlands, namely the Inner Niger Delta, Mali, and the Lake Alaotra area, Madagascar. Sera were first tested using a commercial ID Screen West Nile Competition Multi-species ELISA kit. Then, positive sera and sera with insufficient volume for testing with ELISA were tested with a Microneutralization Test. In Mali, the observed seroprevalence in domestic birds was 28.5% [24.5; 32.8] 95%CI, 3.1 % [1.8; 5.2] 95%CI, 6.2% [3.4; 10.2] 95%CI and 9.8 % [7.3; 12.8] 95%CI, for West Nile virus (WNV), Usutu virus (USUV), undetermined flavivirus, and WNV/USUV respectively. Regarding domestic birds of Madagascar, the observed seroprevalence was 4.4 % [2.1; 7.9]95%CI for WNV, 0.9% [0.1; 3.1] 95%CI for USUV, 1.3% [0.5; 2.8] 95%CI for undetermined flavivirus, and null for WNV/USUV. Among the 150 wild birds sampled in Madagascar, two fulvous whistling-ducks (Dendrocygna bicolor) were positive for WNV and two for an undetermined flavivirus. One white-faced whistling-duck (Dendrocygna viduata) and one Hottentot teal (Spatula hottentota) were tested positive for USUV. African and European wetlands are linked by wild bird migrations. This first detection of USUV—as well as the confirmed circulation of WNV in domestic birds of two wetlands of Mali and Madagascar—emphasizes the need to improve the surveillance, knowledge of epidemiological patterns, and phylogenetic characteristics of flavivirus in Africa, particularly in areas prone to sustained, intense flavivirus transmission such as wetlands.
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Affiliation(s)
- Véronique Chevalier
- CIRAD, UMR ASTRE, F-34090 Montpellier, France
- Université Montpellier, F-34090 Montpellier, France
- Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Phnom Penh PO Box 983, Cambodia
| | - Maud Marsot
- University Paris Est, ANSES, Laboratory for Animal Health, Epidemiology Unit, 94700 Maisons-Alfort, France
| | - Sophie Molia
- CIRAD, UMR ASTRE, F-34090 Montpellier, France
- Université Montpellier, F-34090 Montpellier, France
- Centre Régional de Santé Animale, Parc Sotuba, Bamako, Mali
| | | | | | - Miguel Pedrono
- CIRAD, UMR ASTRE, F-34090 Montpellier, France
- Université Montpellier, F-34090 Montpellier, France
- FOFIFA-DRZV, 101 Antananarivo, Madagascar
| | - Steve Lowenski
- UMR 1161 Virology, ANSES, INRA, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France
| | - Benoit Durand
- University Paris Est, ANSES, Laboratory for Animal Health, Epidemiology Unit, 94700 Maisons-Alfort, France
| | - Sylvie Lecollinet
- UMR 1161 Virology, ANSES, INRA, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France
| | - Cécile Beck
- UMR 1161 Virology, ANSES, INRA, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France
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16
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Jiménez de Oya N, Escribano-Romero E, Blázquez AB, Martín-Acebes MA, Saiz JC. Current Progress of Avian Vaccines Against West Nile Virus. Vaccines (Basel) 2019; 7:vaccines7040126. [PMID: 31547632 PMCID: PMC6963603 DOI: 10.3390/vaccines7040126] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [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: 07/31/2019] [Revised: 09/19/2019] [Accepted: 09/19/2019] [Indexed: 01/15/2023] Open
Abstract
Birds are the main natural host of West Nile virus (WNV), the worldwide most distributed mosquito-borne flavivirus, but humans and equids can also be sporadic hosts. Many avian species have been reported as susceptible to WNV, particularly corvids. In the case that clinical disease develops in birds, this is due to virus invasion of different organs: liver, spleen, kidney, heart, and mainly the central nervous system, which can lead to death 24–48 h later. Nowadays, vaccines have only been licensed for use in equids; thus, the availability of avian vaccines would benefit bird populations, both domestic and wild ones. Such vaccines could be used in endangered species housed in rehabilitation and wildlife reserves, and in animals located at zoos and other recreational installations, but also in farm birds, and in those that are grown for hunting and restocking activities. Even more, controlling WNV infection in birds can also be useful to prevent its spread and limit outbreaks. So far, different commercial and experimental vaccines (inactivated, attenuated, and recombinant viruses, and subunits and DNA-based candidates) have been evaluated, with various regimens, both in domestic and wild avian species. However, there are still disadvantages that must be overcome before avian vaccination can be implemented, such as its cost-effectiveness for domestic birds since in many species the pathogenicity is low or zero, or the viability of being able to achieve collective immunity in wild birds in freedom. Here, a comprehensive review of what has been done until now in the field of avian vaccines against WNV is presented and discussed.
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Affiliation(s)
- Nereida Jiménez de Oya
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Estela Escribano-Romero
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Ana-Belén Blázquez
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Miguel A Martín-Acebes
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Juan-Carlos Saiz
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
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17
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Kumar JS, Rathinam S, Karothia D, Parida M. Cloning, expression & evaluation of potential immunogenic recombinant capsid premembrane protein of West Nile virus. Indian J Med Res 2019; 149:656-661. [PMID: 31417034 PMCID: PMC6702705 DOI: 10.4103/ijmr.ijmr_305_17] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background & objectives: West Nile virus (WNV) is a neurotropic flavivirus that has emerged globally as a significant cause of viral encephalitis. The early confirmatory diagnosis of WNV infections is important for timely clinical management and in areas where multiple flaviviruses are endemic. Diagnosis of WNV infection is primarily based on serodiagnosis, followed by virus isolation and identification. The aim of this study was to develop and evaluate a highly sensitive and specific immunoglobulin M (IgM) ELISA using the recombinant CprM protein (rWNV-CprM) for rapid, early and accurate diagnosis of WNV. Methods: The gene coding for the CprM protein of WNV was cloned and expressed in pET 28a vector followed by purification. An indirect IgM microplate ELISA using purified rWNV-CprM protein was optimized having no cross-reactivity with healthy human serum and serum samples obtained from patients with dengue and Japanese encephalitis viruses infection. Results: The comparative evaluation of this rWNV-CprM protein-specific IgM ELISA with plaque reduction neutralization test using 105 blood samples collected from patients suspected to have acute WNV infection revealed 98 per cent concordance with sensitivity and specificity of 100 and 97 per cent, respectively. Interpretation & conclusions: The recombinant CprM protein-based WNV-specific ELISA reported in this study may be useful for rapid screening of large numbers of blood samples in endemic areas during outbreaks.
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Affiliation(s)
- Jyoti S Kumar
- Division of Virology, Defence Research & Development Establishment, Gwalior, India
| | | | - Divanyshi Karothia
- Division of Virology, Defence Research & Development Establishment, Gwalior, India
| | - Manmohan Parida
- Division of Virology, Defence Research & Development Establishment, Gwalior, India
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Montecino-Latorre D, Barker CM. Overwintering of West Nile virus in a bird community with a communal crow roost. Sci Rep 2018; 8:6088. [PMID: 29666401 DOI: 10.1038/s41598-018-24133-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/22/2018] [Indexed: 02/04/2023] Open
Abstract
In temperate climates, transmission of West Nile virus (WNV) is detectable rarely during the coldest months (late fall through early spring), yet the virus has reappeared consistently during the next warm season. Several mechanisms may contribute to WNV persistence through winter, including bird-to-bird transmission among highly viremic species. Here we consider whether, under realistic scenarios supported by field and laboratory evidence, a winter bird community could sustain WNV through the winter in the absence of mosquitoes. With this purpose we constructed a deterministic model for a community of susceptible birds consisting of communally roosting crows, raptors and other birds. We simulated WNV introduction and subsequent transmission dynamics during the winter under realistic initial conditions and model parameterizations, including plausible contact rates for roosting crows. Model results were used to determine whether the bird community could yield realistic outbreaks that would result in WNV infectious individuals at the end of the winter, which would set up the potential for onward horizontal transmission into summer. Our findings strongly suggest that winter crow roosts could allow for WNV persistence through the winter, and our model results provide synthesis to explain inconclusive results from field studies on WNV overwintering in crow roosts.
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Venter M. Assessing the zoonotic potential of arboviruses of African origin. Curr Opin Virol 2018; 28:74-84. [DOI: 10.1016/j.coviro.2017.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 10/19/2017] [Accepted: 11/02/2017] [Indexed: 12/22/2022]
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Joyce AL, Melese E, Ha PT, Inman A. Population genetic structure of the Culex pipiens (Diptera: Culicidae) complex, vectors of West Nile virus, in five habitats. Parasit Vectors 2018; 11:10. [PMID: 29301567 DOI: 10.1186/s13071-017-2594-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 12/17/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Culex pipiens complex consists of several morphologically similar, closely related species. In the United States, Cx. pipiens L. is distributed North of 39° latitude, while Cx. quinquefasciatus Say occurs South of 36° latitude; a hybrid zone occurs between these two latitudes including in the Central Valley of California. Members of the Cx. pipiens complex and their hybrids are vectors for West Nile virus (WNv). Hybrid offspring of Cx. pipiens and Cx. quinquefasciatus have been found to have enhanced transmission rates of WNv over those of pure populations of each species. We investigated whether hybrids of Cx. pipiens and Cx. quinquefasciatus occurred more frequently in any of five habitats which were dairies, rural, suburban, and urban areas, and wetlands. In addition, the proportion of alleles unique to Cx. quinquefasciatus and Cx. pipiens found in each habitat-associated population were determined. METHODS Amplified fragment length polymorphism (AFLP) markers were used to compare the population structure of the Cx. pipiens complex from each habitat to geographically distant populations considered pure Cx. pipiens and Cx. quinquefasciatus. Structure analyses were used to assign individuals to either Cx. pipiens, Cx. quinquefasciatus, or hybrids of the Cx. pipiens complex. The ancestry of hybrids (F1, F2, or backcrossed) in relation to the two parent populations was estimated for each Central Valley population. Loci unique to the pure Cx. pipiens population and the pure Cx. quinquefasciatus population were determined. The proportion of loci unique to Cx. pipiens and Cx. quinquefasciatus populations were subsequently determined for each population from the five Merced habitats and from the Oroville California population. The unique loci found in Merced populations and not in Cx. pipiens or Cx. quinquefasciatus were also determined. A principal components analysis was run, as was an analysis to determine loci under putative selection. RESULTS The Structure Harvester analysis found K = 3, and the Culex pipiens complex mosquitoes formed a genetic cluster distinct from Cx. quinquefasciatus and Cx. pipiens. Individuals collected from each habitat were nearly all hybrids. However, Cx. pipiens complex collected near dairies had more individuals categorized as Cx. pipiens than collections from the other habitats. None of the mosquitoes collected in Merced or Oroville were considered pure Cx. quinquefasciatus. Significant genetic divergence was detected among the Cx. pipiens complex from the five habitats in Merced; Cx. pipiens complex mosquitoes from dairies were divergent from the urban and suburban populations. New Hybrids analysis found that individuals from all five Merced habitat-associated populations and the population from Oroville were primarily categorized as hybrids backcrossed to the Cx. pipiens population. Finally, all five habitat-associated populations shared more alleles with Cx. pipiens than with Cx. quinquefasciatus, even though the pure Cx. quinquefasciatus population was more geographically proximate to Merced. Results from the principal component analysis, and the occurrence of several unique loci in Merced populations, suggest that Cx. pipiens molestus may also occur in the habitats sampled. CONCLUSIONS Nearly all mosquitoes in the five habitats in Merced in the Central Valley of California area were hybrids of Cx. pipiens and Cx. quinquefasciatus, consisting of hybrids backcrossed to Cx. pipiens. Habitat-associated mosquitoes collected near dairies had more individuals consisting of pure Cx. pipiens, and no mosquitoes from Merced or Oroville CA classified as pure Cx. quinquefasciatus. The genetic distances among Cx. pipiens and Cx. quinquefasciatus, and hybrid populations agree with previous studies using other molecular markers. Cx. pipiens hybrids in Merced shared more alleles with Cx. pipiens than Cx. quinquefasciatus which was unexpected, since Merced is geographically closer to the northern limit of Cx. quinquefasciatus distribution. Culex pipiens molestus may occur in more habitats in the Central Valley than previously suspected, which warrants further investigation. Future studies could investigate the vector competence of hybrids backcrossed to either Cx. pipiens or Cx. quinquefasciatus parent for their ability to transmit West Nile virus.
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Newhouse DJ, Hofmeister EK, Balakrishnan CN. Transcriptional response to West Nile virus infection in the zebra finch ( Taeniopygia guttata). R Soc Open Sci 2017; 4:170296. [PMID: 28680683 PMCID: PMC5493925 DOI: 10.1098/rsos.170296] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/22/2017] [Indexed: 05/04/2023]
Abstract
West Nile virus (WNV) is a widespread arbovirus that imposes a significant cost to both human and wildlife health. WNV exists in a bird-mosquito transmission cycle in which passerine birds act as the primary reservoir host. As a public health concern, the mammalian immune response to WNV has been studied in detail. Little, however, is known about the avian immune response to WNV. Avian taxa show variable susceptibility to WNV and what drives this variation is unknown. Thus, to study the immune response to WNV in birds, we experimentally infected captive zebra finches (Taeniopygia guttata). Zebra finches provide a useful model, as like many natural avian hosts they are moderately susceptible to WNV and thus provide sufficient viremia to infect mosquitoes. We performed RNAseq in spleen tissue during peak viremia to provide an overview of the transcriptional response. In general, we find strong parallels with the mammalian immune response to WNV, including upregulation of five genes in the Rig-I-like receptor signalling pathway, and offer insights into avian-specific responses. Together with complementary immunological assays, we provide a model of the avian immune response to WNV and set the stage for future comparative studies among variably susceptible populations and species.
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Affiliation(s)
- Daniel J. Newhouse
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
- Author for correspondence: Daniel J. Newhouse e-mail:
| | - Erik K. Hofmeister
- US Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711, USA
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Pedersen K, Marks DR, Wang E, Eastwood G, Weaver SC, Goldstein SM, Sinnett DR, DeLiberto TJ. Widespread Detection of Antibodies to Eastern Equine Encephalitis, West Nile, St. Louis Encephalitis, and Turlock Viruses in Various Species of Wild Birds from Across the United States. Am J Trop Med Hyg 2016; 95:206-11. [PMID: 27162269 DOI: 10.4269/ajtmh.15-0840] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 03/22/2016] [Indexed: 12/22/2022] Open
Abstract
Wild birds serve as amplifying hosts for many arboviruses, and are thought to be responsible for introducing these viruses into new areas during migration as well as reintroducing them to places where winter temperatures disrupt mosquito-borne transmission. To learn more about four mosquito-borne arboviruses of concern to human or animal health, we tested sera from 997 wild birds of 54 species and 17 families across 44 states of the United States collected from January 1, 2013, through September 30, 2013. Samples were tested for antibody against eastern equine encephalitis, St. Louis encephalitis, West Nile, and Turlock viruses using plaque reduction neutralization tests with an endpoint of 80% or greater. Of the 333 (33.4%) birds that tested positive for antibody to at least one arbovirus, 29.7% were exposed to two or more arboviruses. Exposure to all four arboviruses was detected in Canada geese, double-crested cormorants, mallards, mute swans, laughing gulls, and American coots. Our results suggest that exposure to arboviruses is widespread in the United States across a diversity of wild bird species.
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Affiliation(s)
- Kerri Pedersen
- U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Fort Collins, Colorado.
| | - David R Marks
- U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Okemos, Michigan
| | - Eryu Wang
- Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas
| | - Gillian Eastwood
- Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas
| | - Scott C Weaver
- Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas
| | - Samuel M Goldstein
- U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Honolulu, Hawaii
| | - David R Sinnett
- U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Palmer, Alaska
| | - Thomas J DeLiberto
- U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado
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23
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Ryan JR. Category C Diseases and Agents. Biosecurity and Bioterrorism 2016. [PMCID: PMC7150296 DOI: 10.1016/b978-0-12-802029-6.00005-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This chapter covers Category C diseases and agents. These emerging diseases present a very unique challenge to public health officials and infectious disease specialists. Perhaps they have been with us for millions of years, lurking in a dark corner of the environment, waiting for an opportunity to jump from their natural cycle of transmission to a human host. Or they may represent something totally new. Regardless of their origin, an emerging disease pathogen must be characterized quickly by molecular biologists and microbiologists. The dynamics of disease transmission must be investigated by teams of epidemiologists. Treatment regimens must be formulated by clinicians working on the frontlines of the outbreak. Disease prevention strategies and risk communications must be quickly formulated by public health officials. Finally, media attention for emerging disease outbreaks forces government officials at all levels to address the problem with planning and preparedness activities aimed at preserving the health of the public. Specific examples explored in this chapter include Nipah virus, hantavirus, West Nile fever virus, and the coronaviruses that cause severe acute respiratory syndrome and Middle East respiratory syndrome.
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Zink SD, Van Slyke GA, Palumbo MJ, Kramer LD, Ciota AT. Exposure to West Nile Virus Increases Bacterial Diversity and Immune Gene Expression in Culex pipiens. Viruses 2015; 7:5619-31. [PMID: 26516902 PMCID: PMC4632394 DOI: 10.3390/v7102886] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [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: 06/24/2015] [Revised: 09/23/2015] [Accepted: 10/15/2015] [Indexed: 11/16/2022] Open
Abstract
Complex interactions between microbial residents of mosquitoes and arboviruses are likely to influence many aspects of vectorial capacity and could potentially have profound effects on patterns of arbovirus transmission. Such interactions have not been well studied for West Nile virus (WNV; Flaviviridae, Flavivirus) and Culex spp. mosquitoes. We utilized next-generation sequencing of 16S ribosomal RNA bacterial genes derived from Culex pipiens Linnaeus following WNV exposure and/or infection and compared bacterial populations and broad immune responses to unexposed mosquitoes. Our results demonstrate that WNV infection increases the diversity of bacterial populations and is associated with up-regulation of classical invertebrate immune pathways including RNA interference (RNAi), Toll, and Jak-STAT (Janus kinase-Signal Transducer and Activator of Transcription). In addition, WNV exposure alone, without the establishment of infection, results in similar alterations to microbial and immune signatures, although to a lesser extent. Multiple bacterial genera were found in greater abundance in WNV-exposed and/or infected mosquitoes, yet the most consistent and notable was the genus Serratia.
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Affiliation(s)
- Steven D Zink
- Griffin Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA.
| | - Greta A Van Slyke
- Griffin Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA.
| | - Michael J Palumbo
- Wadsworth Center Bioinformatics Core, Wadsworth Center, New York State Department of Health, Albany, NY 12222, USA.
| | - Laura D Kramer
- Griffin Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA.
| | - Alexander T Ciota
- Griffin Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA.
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25
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Henning JD, DeGroote L, Dahlin CR. Implementation of a sampling strategy to detect West Nile virus in oral and cloacal samples in live song birds. J Virol Methods 2015; 222:81-4. [PMID: 25863262 DOI: 10.1016/j.jviromet.2015.04.003] [Citation(s) in RCA: 3] [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: 06/10/2014] [Revised: 04/02/2015] [Accepted: 04/02/2015] [Indexed: 11/25/2022]
Abstract
In 1999, West Nile virus (WNV) first appeared in the United States and has subsequently infected more than a million people and untold numbers of wildlife. Though primarily an avian virus, WNV can also infect humans and horses. The current status of WNV and its effects on wildlife in Pennsylvania (PA) is sparsely monitored through sporadic testing of dead birds. In order to acquire a more comprehensive understanding of the status of WNV in wild birds, a study was designed and implemented to sample populations of migratory and local birds at Powdermill Nature Reserve near Rector, PA. Resident and migratory bird species totaling 276 individuals were sampled cloacally and orally to compare the effectiveness of sampling methods. The presence of WNV was tested for using RT-PCR. Two positive samples were found, one from a migrating Tennessee warbler and another from an American robin. The low infection rates indicate that WNV may not be a critical conservation concern in the Westmoreland County region of PA. There was also agreement between oral and cloacal swabs, which provides support for both methods. This study describes a surveillance method that is easily incorporated into any banding operation and which determines the risks of WNV to various bird populations.
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Affiliation(s)
- Jill D Henning
- Department of Biology, University of Pittsburgh at Johnstown, Johnstown, PA 15904, United States.
| | - Lucas DeGroote
- Carnegie Museum of Natural History, Powdermill Avian Research Center, 1847 Route 381, Rector, PA 15677, United States
| | - Christine R Dahlin
- Department of Biology, University of Pittsburgh at Johnstown, Johnstown, PA 15904, United States
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26
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McNamara TS, McLean RG, Saito EK, Wolfe PL, Gillin CM, Fischer JR, Ellis JC, French R, Martin PP, Schuler KL, McRuer D, Clark EE, Hines MK, Marsh C, Szewczyk V, Sladky K, Yon L, Hannant D, Siemer WF. Surveillance of Wildlife Diseases: Lessons from the West Nile Virus Outbreak. Microbiol Spectr 2013; 1. [PMID: 26184818 DOI: 10.1128/microbiolspec.OH-0014-2012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The West Nile virus outbreak of 1999 revealed many weaknesses in this country's ability to respond to disease threats that cross species lines. There were issues of poor communication among human, domestic animal, and wildlife health agencies that delayed diagnosis; a lack of diagnostic capacity of wildlife agencies at the state level; the exclusion of captive wildlife from any surveillance efforts; an inability to visualize the geospatial relationship between the human and avian outbreaks in a timely manner; and marked disparities of funding levels across agencies. Wildlife has played an important role in recent emerging infectious diseases, and it is clear that a One Health approach will be necessary to respond to future threats. The question is, are we any better prepared to recognize and respond to a wildlife-related emerging infectious disease than we were 14 years ago? Have the lessons of WNV been learned?
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27
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Fischer D, Angenvoort J, Ziegler U, Fast C, Maier K, Chabierski S, Eiden M, Ulbert S, Groschup MH, Lierz M. DNA vaccines encoding the envelope protein of West Nile virus lineages 1 or 2 administered intramuscularly, via electroporation and with recombinant virus protein induce partial protection in large falcons (Falco spp.). Vet Res 2015; 46:87. [PMID: 26282836 PMCID: PMC4538736 DOI: 10.1186/s13567-015-0220-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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: 10/16/2014] [Accepted: 07/07/2015] [Indexed: 11/10/2022] Open
Abstract
As West Nile virus (WNV) can cause lethal diseases in raptors, a vaccination prophylaxis of free-living and captive populations is desirable. In the absence of vaccines approved for birds, equine vaccines have been used in falcons, but full protection against WNV infection was not achieved. Therefore, two DNA vaccines encoding the ectodomain of the envelope protein of WNV lineages 1 and 2, respectively, were evaluated in 28 large falcons. Four different vaccination protocols were used, including electroporation and booster-injections of recombinant WNV domain III protein, before challenge with the live WNV lineage 1 strain NY99. Drug safety, plasmid shedding and antibody production were monitored during the vaccination period. Serological, virological, histological, immunohistochemical and molecular biological investigations were performed during the challenge trials. Antibody response following vaccination was low overall and lasted for a maximum of three weeks. Plasmid shedding was not detected at any time. Viremia, mortality and levels, but not duration, of oral virus shedding were reduced in all of the groups during the challenge trial compared to the non-vaccinated control group. Likewise, clinical scoring, levels of cloacal virus shedding and viral load in organs were significantly reduced in three vaccination groups. Histopathological findings associated with WNV infections (meningo-encephalitis, myocarditis, and arteritis) were present in all groups, but immunohistochemical detection of the viral antigen was reduced. In conclusion, the vaccines can be used safely in falcons to reduce mortality and clinical signs and to lower the risk of virus transmission due to decreased levels of virus shedding and viremia, but full protection was not achieved in all groups.
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Affiliation(s)
- Dominik Fischer
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany.
| | - Joke Angenvoort
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Ute Ziegler
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Christine Fast
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Kristina Maier
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany.
| | - Stefan Chabierski
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, 04103, Leipzig, Germany.
| | - Martin Eiden
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Sebastian Ulbert
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, 04103, Leipzig, Germany.
| | - Martin H Groschup
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Michael Lierz
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany.
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28
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Hinton MG, Reisen WK, Wheeler SS, Townsend AK. West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification? J Med Entomol 2015; 52:683-92. [PMID: 26335475 PMCID: PMC4592346 DOI: 10.1093/jme/tjv040] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [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: 09/22/2014] [Accepted: 03/11/2015] [Indexed: 05/19/2023]
Abstract
Since its emergence in North America, West Nile virus (WNV) has had a large impact on equines, humans, and wild bird communities, yet gaps remain in our understanding of how the virus persists at temperate latitudes when winter temperatures preclude virus replication and host-seeking activity by mosquito vectors. Bird-to-bird transmission at large communal American Crow roosts could provide one mechanism for WNV persistence. Herein, we describe seasonal patterns of crow and Culex mosquito abundance, WNV infection rates, and the prevalence of WNV-positive fecal samples at a winter crow roost to test the hypothesis that bird-to-bird transmission allows WNV to persist at winter crow roosts. Samples were collected from large winter crow roosts in the Sacramento Valley of California from January 2013 until August 2014, encompassing two overwintering roost periods. West Nile virus RNA was detected in local crow carcasses in both summer [13/18 (72% WNV positive)] and winter [18/44 (41% WNV positive)] 2013-2014. Winter infections were unlikely to have arisen by recent bites from infected mosquitoes because Culex host-seeking activity was very low in winter and all Culex mosquitoes collected during winter months tested negative for WNV. Opportunities existed for fecal-oral transfer at the overwintering roost: most carcasses that tested positive for WNV had detectable viral RNA in both kidney and cloacal swabs, suggesting that infected crows were shedding virus in their feces, and >50% of crows at the roost were stained with feces by mid-winter. Moreover, 2.3% of fecal samples collected in late summer, when mosquitoes were active, tested positive for WNV RNA. Nevertheless, none of the 1,119 feces collected from three roosts over two winters contained detectable WNV RNA. This study provided evidence of WNV infection in overwintering American crows without mosquito vector activity, but did not elucidate a mechanism of WNV transmission during winter.
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Affiliation(s)
- M G Hinton
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, 1088 Academic Surge, Davis, CA 95616.
| | - W K Reisen
- Department of Pathology, Microbiology, & Immunology, University of California, Davis, Center for Vectorborne Diseases, Old Davis Road, Davis, CA 95616
| | - S S Wheeler
- Department of Pathology, Microbiology, & Immunology, University of California, Davis, Center for Vectorborne Diseases, Old Davis Road, Davis, CA 95616
| | - A K Townsend
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, 1088 Academic Surge, Davis, CA 95616. Department of Biology, Hamilton College, Clinton, NY 13323
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Abstract
West Nile virus (WNV), the most widely distributed virus of the encephalitic flaviviruses, is a vector-borne pathogen of global importance. The transmission cycle exists in rural and urban areas where the virus infects birds, humans, horses and other mammals. Multiple factors impact the transmission and distribution of WNV, related to the dynamics and interactions between pathogen, vector, vertebrate hosts and environment. Hence, among other drivers, weather conditions have direct and indirect influences on vector competence (the ability to acquire, maintain and transmit the virus), on the vector population dynamic and on the virus replication rate within the mosquito, which are mostly weather dependent. The importance of climatic factors (temperature, precipitation, relative humidity and winds) as drivers in WNV epidemiology is increasing under conditions of climate change. Indeed, recent changes in climatic conditions, particularly increased ambient temperature and fluctuations in rainfall amounts, contributed to the maintenance (endemization process) of WNV in various locations in southern Europe, western Asia, the eastern Mediterranean, the Canadian Prairies, parts of the USA and Australia. As predictions show that the current trends are expected to continue, for better preparedness, any assessment of future transmission of WNV should take into consideration the impacts of climate change.
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Affiliation(s)
- Shlomit Paz
- Department of Geography and Environmental Studies, University of Haifa, Israel
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30
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Langevin SA, Bowen RA, Reisen WK, Andrade CC, Ramey WN, Maharaj PD, Anishchenko M, Kenney JL, Duggal NK, Romo H, Bera AK, Sanders TA, Bosco-Lauth A, Smith JL, Kuhn R, Brault AC. Host competence and helicase activity differences exhibited by West Nile viral variants expressing NS3-249 amino acid polymorphisms. PLoS One 2014; 9:e100802. [PMID: 24971589 PMCID: PMC4074097 DOI: 10.1371/journal.pone.0100802] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [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: 03/04/2014] [Accepted: 05/14/2014] [Indexed: 01/27/2023] Open
Abstract
A single helicase amino acid substitution, NS3-T249P, has been shown to increase viremia magnitude/mortality in American crows (AMCRs) following West Nile virus (WNV) infection. Lineage/intra-lineage geographic variants exhibit consistent amino acid polymorphisms at this locus; however, the majority of WNV isolates associated with recent outbreaks reported worldwide have a proline at the NS3-249 residue. In order to evaluate the impact of NS3-249 variants on avian and mammalian virulence, multiple amino acid substitutions were engineered into a WNV infectious cDNA (NY99; NS3-249P) and the resulting viruses inoculated into AMCRs, house sparrows (HOSPs) and mice. Differential viremia profiles were observed between mutant viruses in the two bird species; however, the NS3-249P virus produced the highest mean peak viral loads in both avian models. In contrast, this avian modulating virulence determinant had no effect on LD50 or the neurovirulence phenotype in the murine model. Recombinant helicase proteins demonstrated variable helicase and ATPase activities; however, differences did not correlate with avian or murine viremia phenotypes. These in vitro and in vivo data indicate that avian-specific phenotypes are modulated by critical viral-host protein interactions involving the NS3-249 residue that directly influence transmission efficiency and therefore the magnitude of WNV epizootics in nature.
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Affiliation(s)
- Stanley A. Langevin
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Richard A. Bowen
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - William K. Reisen
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Christy C. Andrade
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Wanichaya N. Ramey
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Payal D. Maharaj
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Michael Anishchenko
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Joan L. Kenney
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Nisha K. Duggal
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Hannah Romo
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Aloke Kumar Bera
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Todd A. Sanders
- United States Fish and Wildlife Service, Portland, Oregon, United States of America
| | - Angela Bosco-Lauth
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Janet L. Smith
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Richard Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Aaron C. Brault
- Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
- * E-mail:
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Mcnamara TS, Mclean RG, Saito EK, Wolff PL, Gillin CM, Fischer JR, Ellis JC, French R, Martin PP, Schuler KL, Mcruer D, Clark EE, Hines MK, Marsh C, Szewczyk V, Sladky K, Yon L, Hannant D, Siemer WF. Surveillance of Wildlife Diseases: Lessons from the West Nile Virus Outbreak. One Health 2014. [DOI: 10.1128/9781555818432.ch16] [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: 11/20/2022] Open
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Pérez-Ramírez E, Llorente F, Jiménez-Clavero MÁ. Experimental infections of wild birds with West Nile virus. Viruses 2014; 6:752-81. [PMID: 24531334 DOI: 10.3390/v6020752] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/04/2014] [Accepted: 02/04/2014] [Indexed: 01/16/2023] Open
Abstract
Avian models of West Nile virus (WNV) disease have become pivotal in the study of infection pathogenesis and transmission, despite the intrinsic constraints that represents this type of experimental research that needs to be conducted in biosecurity level 3 (BSL3) facilities. This review summarizes the main achievements of WNV experimental research carried out in wild birds, highlighting advantages and limitations of this model. Viral and host factors that determine the infection outcome are analyzed in detail, as well as recent discoveries about avian immunity, viral transmission, and persistence achieved through experimental research. Studies of laboratory infections in the natural host will help to understand variations in susceptibility and reservoir competence among bird species, as well as in the epidemiological patterns found in different affected areas.
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Marka A, Diamantidis A, Papa A, Valiakos G, Chaintoutis SC, Doukas D, Tserkezou P, Giannakopoulos A, Papaspyropoulos K, Patsoula E, Badieritakis E, Baka A, Tseroni M, Pervanidou D, Papadopoulos NT, Koliopoulos G, Tontis D, Dovas CI, Billinis C, Tsakris A, Kremastinou J, Hadjichristodoulou C. West Nile virus state of the art report of MALWEST Project. Int J Environ Res Public Health 2013; 10:6534-610. [PMID: 24317379 PMCID: PMC3881129 DOI: 10.3390/ijerph10126534] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/11/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022]
Abstract
During the last three years Greece is experiencing the emergence of West Nile virus (WNV) epidemics. Within this framework, an integrated surveillance and control programme (MALWEST project) with thirteen associate partners was launched aiming to investigate the disease and suggest appropriate interventions. One out of seven work packages of the project is dedicated to the State of the Art report for WNV. Three expert working groups on humans, animals and mosquitoes were established. Medical databases (PubMed, Scopus) were searched together with websites: e.g., WHO, CDC, ECDC. In total, 1,092 relevant articles were initially identified and 258 of them were finally included as references regarding the current knowledge about WNV, along with 36 additional sources (conference papers, reports, book chapters). The review is divided in three sections according to the fields of interest: (1) WNV in humans (epidemiology, molecular characteristics, transmission, diagnosis, treatment, prevention, surveillance); (2) WNV in animals (epidemiological and transmission characteristics concerning birds, horses, reptiles and other animal species) and (3) WNV in mosquitoes (control, surveillance). Finally, some examples of integrated surveillance programmes are presented. The introduction and establishment of the disease in Greece and other European countries further emphasizes the need for thorough research and broadening of our knowledge on this viral pathogen.
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Affiliation(s)
- Andriani Marka
- Department of Microbiology, Faculty of Medicine, University of Athens, Athens 11527, Greece; E-mail:
| | - Alexandros Diamantidis
- Laboratory of Entomology and Agricultural Zoology, School of Agricultural Sciences, University of Thessaly, Volos 38446, Greece; E-mails: (A.D.); (N.T.P.)
| | - Anna Papa
- National Reference Center for Arboviruses, Department of Microbiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece; E-mail:
| | - George Valiakos
- Laboratory of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (G.V); (A.G.); (K.P.); (C.B.)
| | - Serafeim C. Chaintoutis
- Laboratory of Microbiology and Infectious Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece; E-mails: (S.C.C.); (C.I.D.)
| | - Dimitrios Doukas
- Laboratory of Pathology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (D.D.); (D.T.)
| | - Persefoni Tserkezou
- Department of Microbiology, Faculty of Medicine, University of Athens, Athens 11527, Greece; E-mail:
| | - Alexios Giannakopoulos
- Laboratory of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (G.V); (A.G.); (K.P.); (C.B.)
| | - Konstantinos Papaspyropoulos
- Laboratory of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (G.V); (A.G.); (K.P.); (C.B.)
| | - Eleni Patsoula
- Department of Parasitology, Entomology and Tropical Diseases, National School of Public Health, Athens 11521, Greece; E-mail:
| | - Evangelos Badieritakis
- Laboratory of Biological Control of Pesticides, Benaki Phytopathological Institute, Athens 14561, Greece; E-mails: (E.B.); (G.K.)
| | - Agoritsa Baka
- Hellenic Centre for Disease Control and Prevention (KEELPNO), Athens 15123, Greece; E-mails: (A.B.); (M.T.); (D.P.); (J.K.)
| | - Maria Tseroni
- Hellenic Centre for Disease Control and Prevention (KEELPNO), Athens 15123, Greece; E-mails: (A.B.); (M.T.); (D.P.); (J.K.)
| | - Danai Pervanidou
- Hellenic Centre for Disease Control and Prevention (KEELPNO), Athens 15123, Greece; E-mails: (A.B.); (M.T.); (D.P.); (J.K.)
| | - Nikos T. Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, School of Agricultural Sciences, University of Thessaly, Volos 38446, Greece; E-mails: (A.D.); (N.T.P.)
| | - George Koliopoulos
- Laboratory of Biological Control of Pesticides, Benaki Phytopathological Institute, Athens 14561, Greece; E-mails: (E.B.); (G.K.)
| | - Dimitrios Tontis
- Laboratory of Pathology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (D.D.); (D.T.)
| | - Chrysostomos I. Dovas
- Laboratory of Microbiology and Infectious Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece; E-mails: (S.C.C.); (C.I.D.)
| | - Charalambos Billinis
- Laboratory of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Thessaly, Karditsa 43100, Greece; E-mails: (G.V); (A.G.); (K.P.); (C.B.)
| | - Athanassios Tsakris
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +30-2410-565-007; Fax: +30-2410-565-051
| | - Jenny Kremastinou
- Hellenic Centre for Disease Control and Prevention (KEELPNO), Athens 15123, Greece; E-mails: (A.B.); (M.T.); (D.P.); (J.K.)
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Prow NA. The changing epidemiology of Kunjin virus in Australia. Int J Environ Res Public Health 2013; 10:6255-72. [PMID: 24287851 DOI: 10.3390/ijerph10126255] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 11/04/2013] [Accepted: 11/07/2013] [Indexed: 12/02/2022]
Abstract
West Nile virus (WNV) is a mosquito-borne virus responsible for outbreaks of viral encephalitis in humans and horses, with particularly virulent strains causing recent outbreaks of disease in Eastern Europe, the Middle East and North America. A strain of WNV, Kunjin (WNVKUN), is endemic in northern Australia and infection with this virus is generally asymptomatic. However in early 2011, an unprecedented outbreak of encephalitis in horses occurred in south-eastern Australia, resulting in mortality in approximately 10%–15% of infected horses. A WNV-like virus (WNVNSW2011) was isolated and found to be most closely related to the indigenous WNVKUN, rather than other exotic WNV strains. Furthermore, at least two amino acid changes associated with increased virulence of the North American New York 99 strain (WNVNY99) compared to the prototype WNVKUN were present in the WNVNSW2011 sequence. This review summarizes our current understanding of WNVKUN and how the epidemiology and ecology of this virus has changed. Analysis of virulence determinants of contemporary WNVKUN isolates will provide clues on where virulent strains have emerged in Australia. A better understanding of the changing ecology and epidemiology associated with the emergence of virulent strains is essential to prepare for future outbreaks of WNV disease in Australia.
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Abstract
The introduction, dispersal and establishment of West Nile virus in North America were reviewed, focusing on factors that may have enhanced receptivity and enabled the invasion process. The overwintering persistence of this tropical virus within temperate latitudes was unexpected, but was key in the transition from invasion to endemic establishment. The cascade of temporal events allowing sporadic amplification to outbreak levels was discussed within a future perspective.
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Affiliation(s)
- N. M. Nemeth
- Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine; University of Georgia; Athens Georgia 30602 USA
- Department of Pathobiology; Ontario Veterinary College; University of Guelph; Guelph Ontario N1G 2W1 Canada
| | - P. T. Oesterle
- Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine; University of Georgia; Athens Georgia 30602 USA
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Paz S, Semenza JC. Environmental drivers of West Nile fever epidemiology in Europe and Western Asia--a review. Int J Environ Res Public Health 2013; 10:3543-62. [PMID: 23939389 PMCID: PMC3774453 DOI: 10.3390/ijerph10083543] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 07/25/2013] [Accepted: 08/01/2013] [Indexed: 12/14/2022]
Abstract
Abiotic and biotic conditions are both important determinants of West Nile Fever (WNF) epidemiology. Ambient temperature plays an important role in the growth rates of vector populations, the interval between blood meals, viral replication rates and transmission of West Nile Virus (WNV). The contribution of precipitation is more complex and less well understood. In this paper we discuss impacts of climatic parameters (temperature, relative humidity, precipitation) and other environmental drivers (such as bird migration, land use) on WNV transmission in Europe. WNV recently became established in southeastern Europe, with a large outbreak in the summer of 2010 and recurrent outbreaks in 2011 and 2012. Abundant competent mosquito vectors, bridge vectors, infected (viremic) migrating and local (amplifying) birds are all important characteristics of WNV transmission. In addition, certain key climatic factors, such as increased ambient temperatures, and by extension climate change, may also favor WNF transmission, and they should be taken into account when evaluating the risk of disease spread in the coming years. Monitoring epidemic precursors of WNF, such as significant temperature deviations in high risk areas, could be used to trigger vector control programs and public education campaigns.
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Affiliation(s)
- Shlomit Paz
- Department of Geography and Environmental Studies, University of Haifa, Mt. Carmel, Haifa 3498837, Israel
| | - Jan C. Semenza
- European Centre for Disease Prevention and Control (ECDC), Tomtebodavägen 11A, Stockholm 17183, Sweden; E-Mail:
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VanDalen KK, Hall JS, Clark L, McLean RG, Smeraski C. West Nile virus infection in American Robins: new insights on dose response. PLoS One 2013; 8:e68537. [PMID: 23844218 PMCID: PMC3699668 DOI: 10.1371/journal.pone.0068537] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 06/05/2013] [Indexed: 12/20/2022] Open
Abstract
West Nile virus (WNV) is a vector-borne pathogen that was first detected in the United States in 1999. The natural transmission cycle of WNV involves mosquito vectors and avian hosts, which vary in their competency to transmit the virus. American robins are an abundant backyard species in the United States and appear to have an important role in the amplification and dissemination of WNV. In this study we examine the response of American robins to infection with various WNV doses within the range of those administered by some natural mosquito vectors. Thirty American robins were assigned a WNV dosage treatment and needle inoculated with 10(0.95) PFU, 10(1.26) PFU, 10(2.15) PFU, or 10(3.15) PFU. Serum samples were tested for the presence of infectious WNV and/or antibodies, while oral swabs were tested for the presence of WNV RNA. Five of the 30 (17%) robins had neutralizing antibodies to WNV prior to the experiment and none developed viremia or shed WNV RNA. The proportion of WNV-seronegative birds that became viremic after WNV inoculation increased in a dose dependent manner. At the lowest dose, only 40% (2/5) of the inoculated birds developed productive infections while at the highest dose, 100% (7/7) of the birds became viremic. Oral shedding of WNV RNA followed a similar trend where robins inoculated with the lower two doses were less likely to shed viral RNA (25%) than robins inoculated with one of the higher doses (92%). Viremia titers and morbidity did not increase in a dose dependent manner; only two birds succumbed to infection and, interestingly, both were inoculated with the lowest dose of WNV. It is clear that the disease ecology of WNV is a complex interplay of hosts, vectors, and viral dose delivered.
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Affiliation(s)
- Kaci K VanDalen
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, United States of America.
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Dridi M, Vangeluwe D, Lecollinet S, van den Berg T, Lambrecht B. Experimental infection of Carrion crows (Corvus corone) with two European West Nile virus (WNV) strains. Vet Microbiol 2013; 165:160-6. [DOI: 10.1016/j.vetmic.2012.12.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 12/14/2012] [Accepted: 12/18/2012] [Indexed: 11/22/2022]
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Sovada MA, Pietz PJ, Hofmeister EK, Bartos AJ. West Nile virus in American White Pelican chicks: transmission, immunity, and survival. Am J Trop Med Hyg 2013; 88:1152-8. [PMID: 23530073 DOI: 10.4269/ajtmh.12-0408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
West Nile virus (WNV) causes significant mortality of American White Pelican chicks at northern plains colonies. We tested oropharyngeal/cloacal swabs from moribund chicks for shed WNV. Such shedding could enable chick-to-chick transmission and help explain why WNV spreads rapidly in colonies. WNV was detected on swabs from 11% of chicks in 2006 and 52% of chicks in 2007; however, viral titers were low. Before onset of WNV mortality, we tested blood from < 3-week-old chicks for antibodies to WNV; 5% of chicks were seropositive, suggesting passive transfer of maternal antibodies. Among near-fledged chicks, 41% tested positive for anti-WNV antibodies, indicating that they survived infection. Among years and colonies, cumulative incidence of WNV in chicks varied from 28% to 81%, whereas the proportion of chicks surviving WNV (i.e., seropositive) was 64-75%. Our data revealed that WNV kills chicks that likely would fledge in the absence of WNV, that infection of chicks is pervasive, and that significant numbers of chicks survive infection.
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Affiliation(s)
- Marsha A Sovada
- US Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, ND 58401, USA.
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41
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Paz S, Malkinson D, Green MS, Tsioni G, Papa A, Danis K, Sirbu A, Ceianu C, Katalin K, Ferenczi E, Zeller H, Semenza JC. Permissive summer temperatures of the 2010 European West Nile fever upsurge. PLoS One 2013; 8:e56398. [PMID: 23431374 PMCID: PMC3576399 DOI: 10.1371/journal.pone.0056398] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 01/09/2013] [Indexed: 11/30/2022] Open
Abstract
Background In the summer of 2010, Europe experienced outbreaks of West Nile Fever (WNF) in humans, which was preceded by hot spells. The objective of this study was to identify potential drivers of these outbreaks, such as spring and summer temperatures, relative humidity (RH), and precipitation. Methods Pearson and lag correlations, binary and multinomial logistic regressions were used to assess the relationship between the climatic parameters and these outbreaks. Results For human morbidity, significant (<0.05) positive correlations were observed between a number of WNF cases and temperature, with a geographic latitude gradient: northern (“colder”) countries displayed strong correlations with a lag of up to four weeks, in contrast to southern (“warmer”) countries, where the response was immediate. The correlations with RH were weaker, while the association with precipitation was not consistent. Horse morbidity started three weeks later than in humans where integrated surveillance was conducted, and no significant associations with temperature or RH were found for lags of 0 to 4 weeks. Conclusions Significant temperature deviations during summer months might be considered environmental precursors of WNF outbreaks in humans, particularly at more northern latitudes. These insights can guide vector abatement strategies by health practitioners in areas at risk for persistent transmission cycles.
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Affiliation(s)
- Shlomit Paz
- Department of Geography and Environmental Studies, University of Haifa, Haifa, Israel
| | - Dan Malkinson
- Department of Geography and Environmental Studies, University of Haifa, Haifa, Israel
| | | | - Gil Tsioni
- Department of Geography and Environmental Studies, University of Haifa, Haifa, Israel
| | - Anna Papa
- Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Kostas Danis
- Hellenic Centre of Disease Prevention & Control, Athens, Greece
| | - Anca Sirbu
- National Center for Surveillance and Control of Communicable Diseases, Bucharest, Romania
| | - Cornelia Ceianu
- Cantacuzino National Institute for Research and Development in Microbiology and Immunology, Bucharest, Romania
| | | | | | - Herve Zeller
- European Center for Disease Prevention and Control (ECDC), Stockholm, Sweden
| | - Jan C. Semenza
- European Center for Disease Prevention and Control (ECDC), Stockholm, Sweden
- * E-mail:
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Abstract
Vector-borne zoonotic disease agents, which are known to often infect multiple species in the wild, have been identified as an emerging threat to human health. Understanding the ecology of these pathogens is especially timely, given the continued anthropogenic impacts on biodiversity. Here, we integrate empirical scaling laws from community ecology within a theoretical reservoir-vector-pathogen framework to study the transmission consequences of host community structure and diversity within large assemblages. We show that heterogeneity in susceptibility of the reservoir species promotes transmission "dilution," while a greater vector species richness "amplifies" it. These contrasting transmission impacts of vector and reservoir communities can yield very different epidemiological patterns. We demonstrate that vector and reservoir species richness can explain per se most of the pathogen transmission observed for West Nile virus in different parts of the United States, giving empirical support for the validity of these opposing theoretically predicted effects. We conclude that, in the context of disease emergence, the integration of a community perspective can provide critical insights into the understanding of pathogen transmission in wildlife.
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Affiliation(s)
- Benjamin Roche
- Unité Mixte Internationale (UMI) Unité de Modélisation Mathématique et Informatique des Systèmes Complexes (UMMISCO) IRD-UPMC 209, Centre IRD France Nord, 93143 Bondy, France.
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Abstract
The renewed interest in the concept of One Health has occurred as a result of the increased emergence of zoonotic infectious diseases over the past decade. The subsequent impacts of these diseases on human, livestock, and wildlife health, as well as the economic effects, have given international health organizations and national governments a greater appreciation of the importance of collaborative efforts in solving health problems. The One Health concept is not new, but under its umbrella, a new generation of veterinarians, physicians, ecologists, biologists, and social scientists is shaping the concept in novel ways. This has led to increased support for One Health initiatives to control disease by international agencies, national governments, and nongovernmental organizations as well as a growing emphasis on One Health concepts in training the veterinary workforce. Veterinary schools are reorganizing veterinary education to better teach students the precepts of One Health. This chapter explores the evolution and application of the One Health concept from the perspective of the veterinarian. The veterinary profession is positioned to be a strong advocate and leader of One Health. Veterinarians have a long history of involvement with One Health activities, and this involvement has adjusted and shifted with the changing needs of society. A new area of work for veterinarians is ecosystem health, which is becoming more relevant as a result of the impact that the ever-increasing human population is having on the environment that supports them.
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Affiliation(s)
- John S. Mackenzie
- grid.1032.00000000403754078Faculty of Health Sciences, Curtin University, Perth, Perth, West Australia Australia
| | - Martyn Jeggo
- Livestock Industries, CSIRO Australian Animal Health Laborator, East Geelong, Victoria Australia
| | - Peter Daszak
- grid.420826.a0000000404094702EcoHealth Alliance, New York, New York USA
| | - Juergen A. Richt
- grid.36567.310000000107371259Diagnostic Medicine/Pathobiology Departm, Kansas State University College of Veterinary Medicine, Manhattan, Kansas USA
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Abstract
West Nile virus (WNV), a flavivirus of the Flaviviridae family, is maintained in nature in an enzootic transmission cycle between avian hosts and ornithophilic mosquito vectors, although the virus occasionally infects other vertebrates. WNV causes sporadic disease outbreaks in horses and humans, which may result in febrile illness, meningitis, encephalitis and flaccid paralysis. Until recently, its medical and veterinary health concern was relatively low; however, the number, frequency and severity of outbreaks with neurological consequences in humans and horses have lately increased in Europe and the Mediterranean basin. Since its introduction in the Americas, the virus spread across the continent with worrisome consequences in bird mortality and a considerable number of outbreaks among humans and horses, which have resulted in the largest epidemics of neuroinvasive WNV disease ever documented. Surprisingly, its incidence in human and animal health is very different in Central and South America, and the reasons for it are not yet understood. Even though great advances have been obtained lately regarding WNV infection, and although efficient equine vaccines are available, no specific treatments or vaccines for human use are on the market. This review updates the most recent investigations in different aspects of WNV life cycle: molecular virology, transmission dynamics, host range, clinical presentations, epidemiology, ecology, diagnosis, control, and prevention, and highlights some aspects that certainly require further research.
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Affiliation(s)
- Miguel A Martín-Acebes
- Miguel A Martín-Acebes, Juan-Carlos Saiz, Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, 28040 Madrid, Spain
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Sotelo E, Fernández-Pinero J, Jiménez-Clavero MÁ. La fiebre/encefalitis por virus West Nile: reemergencia en Europa y situación en España. Enferm Infecc Microbiol Clin 2012; 30:75-83. [DOI: 10.1016/j.eimc.2011.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 12/29/2022]
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Pesko KN, Ebel GD. West Nile virus population genetics and evolution. Infect Genet Evol 2011; 12:181-90. [PMID: 22226703 DOI: 10.1016/j.meegid.2011.11.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/29/2011] [Accepted: 11/30/2011] [Indexed: 12/18/2022]
Abstract
West Nile virus (WNV) (Flaviviridae: Flavivirus) is transmitted from mosquitoes to birds, but can cause fatal encephalitis in infected humans. Since its introduction into North America in New York in 1999, it has spread throughout the western hemisphere. Multiple outbreaks have also occurred in Europe over the last 20 years. This review highlights recent efforts to understand how host pressures impact viral population genetics, genotypic and phenotypic changes which have occurred in the WNV genome as it adapts to this novel environment, and molecular epidemiology of WNV worldwide. Future research directions are also discussed.
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Affiliation(s)
- Kendra N Pesko
- Department of Pathology, University of New Mexico School of Medicine, 1 University of New Mexico, Albuquerque, NM 87131, USA
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Carney RM, Ahearn SC, McConchie A, Glasner C, Jean C, Barker C, Park B, Padgett K, Parker E, Aquino E, Kramer V. Early warning system for West Nile virus risk areas, California, USA. Emerg Infect Dis 2011; 17:1445-54. [PMID: 21801622 PMCID: PMC3381548 DOI: 10.3201/eid1708.100411] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [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] [Indexed: 11/19/2022] Open
Abstract
The Dynamic Continuous-Area Space-Time (DYCAST) system is a biologically based spatiotemporal model that uses public reports of dead birds to identify areas at high risk for West Nile virus (WNV) transmission to humans. In 2005, during a statewide epidemic of WNV (880 cases), the California Department of Public Health prospectively implemented DYCAST over 32,517 km2 in California. Daily risk maps were made available online and used by local agencies to target public education campaigns, surveillance, and mosquito control. DYCAST had 80.8% sensitivity and 90.6% specificity for predicting human cases, and k analysis indicated moderate strength of chance-adjusted agreement for >4 weeks. High-risk grid cells (populations) were identified an average of 37.2 days before onset of human illness; relative risk for disease was >39× higher than for low-risk cells. Although prediction rates declined in subsequent years, results indicate DYCAST was a timely and effective early warning system during the severe 2005 epidemic.
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Affiliation(s)
- Ryan M Carney
- California Department of Public Health, Richmond, California, USA.
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Magori K, Bajwa WI, Bowden S, Drake JM. Decelerating spread of West Nile virus by percolation in a heterogeneous urban landscape. PLoS Comput Biol 2011; 7:e1002104. [PMID: 21829332 PMCID: PMC3145642 DOI: 10.1371/journal.pcbi.1002104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 05/12/2011] [Indexed: 01/05/2023] Open
Abstract
Vector-borne diseases are emerging and re-emerging in urban environments throughout the world, presenting an increasing challenge to human health and a major obstacle to development. Currently, more than half of the global population is concentrated in urban environments, which are highly heterogeneous in the extent, degree, and distribution of environmental modifications. Because the prevalence of vector-borne pathogens is so closely coupled to the ecologies of vector and host species, this heterogeneity has the potential to significantly alter the dynamical systems through which pathogens propagate, and also thereby affect the epidemiological patterns of disease at multiple spatial scales. One such pattern is the speed of spread. Whereas standard models hold that pathogens spread as waves with constant or increasing speed, we hypothesized that heterogeneity in urban environments would cause decelerating travelling waves in incipient epidemics. To test this hypothesis, we analysed data on the spread of West Nile virus (WNV) in New York City (NYC), the 1999 epicentre of the North American pandemic, during annual epizootics from 2000–2008. These data show evidence of deceleration in all years studied, consistent with our hypothesis. To further explain these patterns, we developed a spatial model for vector-borne disease transmission in a heterogeneous environment. An emergent property of this model is that deceleration occurs only in the vicinity of a critical point. Geostatistical analysis suggests that NYC may be on the edge of this criticality. Together, these analyses provide the first evidence for the endogenous generation of decelerating travelling waves in an emerging infectious disease. Since the reported deceleration results from the heterogeneity of the environment through which the pathogen percolates, our findings suggest that targeting control at key sites could efficiently prevent pathogen spread to remote susceptible areas or even halt epidemics. Current theory of the spatial spread of pathogens predicts travelling waves at constant or increasing speed in homogeneous environments. However, in urban environments, increasing and often unregulated development produces a highly heterogeneous landscape. Such heterogeneity affects pathogens spread by insect vectors particularly, which typically have short dispersal distances. We hypothesized that high levels of heterogeneity can slow the spread of such pathogens, resulting in decelerating epidemic waves. We analysed the annual spread of West Nile virus (WNV) in New York City (NYC), using a dataset containing >1,000,000 records since the origin of the North American pandemic in 1999. Our analysis provides the first evidence of endogenous decelerating travelling waves in an emerging infectious disease. We found that WNV spread with decreasing speed in each season and rejected four alternative hypotheses to explain this deceleration. A mathematical model shows that high levels of heterogeneity can lead to such decelerating travelling waves. Interestingly, the level of heterogeneity in land-cover types associated with WNV-positive dead birds in NYC is of the order of magnitude required to produce decelerating travelling waves in the model. Consequently, we propose that control strategies targeting key sites may be effective at slowing WNV spread in NYC.
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Affiliation(s)
- Krisztian Magori
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America.
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Owen JC, Moore FR, Williams AJ, Stark L, Miller EA, Morley VJ, Krohn AR, Garvin MC. Test of recrudescence hypothesis for overwintering of eastern equine encephalomyelitis virus in gray catbirds. J Med Entomol 2011; 48:896-903. [PMID: 21845951 DOI: 10.1603/me10274] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) epizootics are infrequent, but they can lead to high mortality in infected horses and humans. Despite the importance of EEEV to human and animal health, little is known about how the virus overwinters and reinitiates transmission each spring, particularly in temperate regions where infected adult mosquitoes are unlikely to survive through the winter. One hypothesis to explain the mechanism by which this virus persists from year to year is the spring recrudescence of latent virus in avian reservoir hosts. In this study, we tested the recrudescence hypothesis with gray catbirds (Dumatella carolinensis) captured in northern Ohio (July-August 2007). Birds were experimentally infected with EEEV on 1 October 2007. In January 2008, they were then exposed to exogenous testosterone and/or extended photoperiod to initiate reactivation of latent EEEV infection. All birds became viremic with EEEV, with mean viremia of 6.0 log10 plaque-forming units/ml serum occurring at 1 d postinoculation. One male in the testosterone, long-day treatment group had EEEV viral RNA in a cloacal swab collected on 18 January 2008. Otherwise, no other catbirds exhibited reactivated infections in cloacal swabs or blood. Antibody titers fluctuated over the course of the study, with lowest titers observed in January 2008, which corresponded with the lowest mean weight of the birds. No EEEV viral RNA was detected in the blood, kidney, spleen, brain, liver, and lower intestine upon necropsy at 19 wk postinfection.
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Affiliation(s)
- Jennifer C Owen
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 44824, USA.
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