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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: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [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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2
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Batallán GP, Konigheim BS, Quaglia AI, Rivarola ME, Beranek MD, Tauro LB, Flores SF, Laurito M, Almirón WR, Contigiani MS, Visintin AM. Autochthonous circulation of Saint Louis encephalitis and West Nile viruses in the Province of La Rioja, Argentina. Rev Argent Microbiol 2020; 53:154-161. [PMID: 33176955 DOI: 10.1016/j.ram.2020.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/29/2020] [Accepted: 09/02/2020] [Indexed: 11/16/2022] Open
Abstract
St. Louis encephalitis (SLEV) and West Nile (WNV) arboviruses, which circulate in Argentina, are maintained in enzootic transmission cycles involving Culex mosquitoes (vectors) and birds belonging to orders Passeriformes and Columbiformes (amplifier hosts). The objective of this work was to determine the circulation of both viruses among wild birds in a semiarid ecosystem in the Province of La Rioja through a serologic survey. During spring 2013 and fall 2014, a total of 326 wild birds belonging to 41 species were captured in areas close to the cities of La Rioja and Chilecito, in the Province of La Rioja. While exposure to SLEV and WNV was analyzed in birds' serum through neutralizing antibody detection, viral circulation was estimated through apparent seroprevalence of neutralizing antibodies. The exposure of the avian community to viruses was 3.02% for SLEV and 1.89% for WNV, while 1.19% corresponded to coinfections. Our study confirms for the first time the circulation of SLEV and WNV in wild birds in the Province of La Rioja. Moreover, it is the first study to register neutralizing antibodies for flavivirus in the species Leptotila verreauxi (White-tipped Dove) (WNV) and Melanerpes cactorum (White-fronted Woodpecker) (SLEV). These results suggest that in semiarid ecosystems from northwestern Argentina the requirements and conditions for amplification and enzootic maintenance of SLEV and WNV would be present.
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Affiliation(s)
- Gonzalo P Batallán
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina; Departamento de Ciencias Básicas y Tecnológicas, Universidad Nacional de Chilecito, La Rioja, Argentina
| | - Brenda S Konigheim
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Agustín I Quaglia
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina; Florida Medical Entomology Laboratory, University of Florida, Vero Beach, FL, USA
| | - María E Rivarola
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Mauricio D Beranek
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Laura B Tauro
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; Instituto de Biología Subtropical, nodo Iguazú, CONICET, Universidad Nacional de Misiones, Argentina
| | - Sebastián F Flores
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; Laboratorio de Ecología de Enfermedades, Instituto de Ciencias Veterinarias del Litoral (ICiVet-Litoral), Universidad Nacional del Litoral/CONICET, Esperanza, Santa Fe, Argentina
| | - Magdalena Laurito
- Universidad Nacional de Córdoba, Centro de Investigaciones Entomológicas de Córdoba,Facultad de Ciencias Exactas, Físicas y Naturales, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigaciones Biológicas y Tecnológicas, Córdoba, Argentina
| | - Walter R Almirón
- Universidad Nacional de Córdoba, Centro de Investigaciones Entomológicas de Córdoba,Facultad de Ciencias Exactas, Físicas y Naturales, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigaciones Biológicas y Tecnológicas, Córdoba, Argentina
| | - Marta S Contigiani
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Instituto de Virología "Dr. J. M. Vanella", Enfermera Gordillo S/N, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Andrés M Visintin
- Universidad Nacional de Córdoba, Centro de Investigaciones Entomológicas de Córdoba,Facultad de Ciencias Exactas, Físicas y Naturales, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigaciones Biológicas y Tecnológicas, Córdoba, Argentina; Instituto de Biología de la Conservación y Paleobiología (IBiCoPa), Centro de Investigación e Innovación Tecnológica (CENIIT), Universidad Nacional de la Rioja, La Rioja, Argentina.
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3
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Ramírez AL, van den Hurk AF, Meyer DB, Ritchie SA. Searching for the proverbial needle in a haystack: advances in mosquito-borne arbovirus surveillance. Parasit Vectors 2018; 11:320. [PMID: 29843778 PMCID: PMC5975710 DOI: 10.1186/s13071-018-2901-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/15/2018] [Indexed: 02/08/2023] Open
Abstract
Surveillance is critical for the prevention and control of mosquito-borne arboviruses. Detection of elevated or emergent virus activity serves as a warning system to implement appropriate actions to reduce outbreaks. Traditionally, surveillance of arboviruses has relied on the detection of specific antibodies in sentinel animals and/or detection of viruses in pools of mosquitoes collected using a variety of sampling methods. These methods, although immensely useful, have limitations, including the need for a cold chain for sample transport, cross-reactivity between related viruses in serological assays, the requirement for specialized equipment or infrastructure, and overall expense. Advances have recently been made on developing new strategies for arbovirus surveillance. These strategies include sugar-based surveillance, whereby mosquitoes are collected in purpose-built traps and allowed to expectorate on nucleic acid preservation cards which are submitted for virus detection. New diagnostic approaches, such as next-generation sequencing, have the potential to expand the genetic information obtained from samples and aid in virus discovery. Here, we review the advancement of arbovirus surveillance systems over the past decade. Some of the novel approaches presented here have already been validated and are currently being integrated into surveillance programs. Other strategies are still at the experimental stage, and their feasibility in the field is yet to be evaluated.
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Affiliation(s)
- Ana L Ramírez
- College of Public Health, Medical and Veterinary Sciences, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia.
| | - Andrew F van den Hurk
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, QLD, 4108, Australia
| | - Dagmar B Meyer
- College of Public Health, Medical and Veterinary Sciences, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia.,Astralian Institute of Tropical Health and Medicine, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia
| | - Scott A Ritchie
- College of Public Health, Medical and Veterinary Sciences, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia.,Astralian Institute of Tropical Health and Medicine, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia
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4
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Abstract
Equine populations worldwide are at increasing risk of infection by viruses transmitted by biting arthropods, including mosquitoes, biting midges (Culicoides), sandflies and ticks. These include the flaviviruses (Japanese encephalitis, West Nile and Murray Valley encephalitis), alphaviruses (eastern, western and Venezuelan encephalitis) and the orbiviruses (African horse sickness and equine encephalosis). This review provides an overview of the challenges faced in the surveillance, prevention and control of the major equine arboviruses, particularly in the context of these viruses emerging in new regions of the world.
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Affiliation(s)
- G E Chapman
- Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - M Baylis
- Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - D Archer
- Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - J M Daly
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, UK
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5
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Hesson JC, Lundström JO, Tok A, Östman Ö, Lundkvist Å. Temporal Variation in Sindbis Virus Antibody Prevalence in Bird Hosts in an Endemic Area in Sweden. PLoS One 2016; 11:e0162005. [PMID: 27579607 PMCID: PMC5007008 DOI: 10.1371/journal.pone.0162005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/16/2016] [Indexed: 11/25/2022] Open
Abstract
Sindbis virus (SINV) is a mosquito-borne bird virus that occasionally causes human disease in Fennoscandia, suggested to have cyclic 7-year intervals between outbreaks. Reliable data on human infections in Sweden is however lacking. Here we investigated the SINV antibody prevalence among birds in a Swedish area endemic to SINV to scrutinize if a cyclic variation in antibody prevalence is present in the natural host of SINV. Serum from birds were sampled in the summers of 2002–2004 and 2009 in the floodplains of the River Dalälven in central Sweden, with 2002 and 2009 representing hypothesized years of SINV outbreaks. A total of 963 birds from 52 species (mainly passerines) were tested for the presence of SINV antibodies using a plaque reduction neutralization test. The highest SINV antibody prevalence was found in Turdidae species, specifically Fieldfare, Redwing and Song thrush in which more than 70% of sampled individuals had antibodies to SINV in 2009. The SINV antibody prevalence significantly varied between years with 2% in 2002, 8% in 2003, 14% in 2004 and 37% in 2009. Antibodies were found equally often in hatchlings and in adults and increased from early to late in the season. Clearly, the SINV antibody prevalence was not elevated in the bird hosts in the predicted outbreak year 2002, thus solid evidence of a cyclic occurrence of SINV in Sweden is still lacking.
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Affiliation(s)
- Jenny Christina Hesson
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, Uppsala, Sweden.,Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Jan O Lundström
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, Uppsala, Sweden.,Swedish Biological Mosquito Control Project, Nedre Dalälvens Utvecklings AB, Gysinge, Sweden
| | - Atalay Tok
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, Uppsala, Sweden
| | - Örjan Östman
- Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Öregrund, Sweden
| | - Åke Lundkvist
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, Uppsala, Sweden.,Laboratory of Clinical Microbiology, Uppsala University Hospital, Uppsala, Sweden
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6
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Healy JM, Reisen WK, Kramer VL, Fischer M, Lindsey NP, Nasci RS, Macedo PA, White G, Takahashi R, Khang L, Barker CM. Comparison of the efficiency and cost of West Nile virus surveillance methods in California. Vector Borne Zoonotic Dis 2016; 15:147-55. [PMID: 25700046 DOI: 10.1089/vbz.2014.1689] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Surveillance systems for West Nile virus (WNV) combine several methods to determine the location and timing of viral amplification. The value of each surveillance method must be measured against its efficiency and costs to optimize integrated vector management and suppress WNV transmission to the human population. Here we extend previous comparisons of WNV surveillance methods by equitably comparing the most common methods after standardization on the basis of spatial sampling density and costs, and by estimating optimal levels of sampling effort for mosquito traps and sentinel chicken flocks. In general, testing for evidence of viral RNA in mosquitoes and public-reported dead birds resulted in detection of WNV approximately 2-5 weeks earlier than serological monitoring of sentinel chickens at equal spatial sampling density. For a fixed cost, testing of dead birds reported by the public was found to be the most cost effective of the methods, yielding the highest number of positive results per $1000. Increased spatial density of mosquito trapping was associated with more precise estimates of WNV infection prevalence in mosquitoes. Our findings also suggested that the most common chicken flock size of 10 birds could be reduced to six to seven without substantial reductions in timeliness or sensitivity. We conclude that a surveillance system that uses the testing of dead birds reported by the public complemented by strategically timed mosquito and chicken sampling as agency resources allow would detect viral activity efficiently in terms of effort and costs, so long as susceptible bird species that experience a high mortality rate from infection with WNV, such as corvids, are present in the area.
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Affiliation(s)
- Jessica M Healy
- 1 Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, University of California , Davis, California
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7
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Affiliation(s)
- John E Greenlee
- Department of Neurology, George E. Wahlen Veterans Affairs Medical Center, University of Utah Health Sciences, Salt Lake City, UT, USA.
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8
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Diseases at the livestock-wildlife interface: status, challenges, and opportunities in the United States. Prev Vet Med 2012; 110:119-32. [PMID: 23254245 PMCID: PMC7127607 DOI: 10.1016/j.prevetmed.2012.11.021] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 11/17/2012] [Accepted: 11/19/2012] [Indexed: 01/31/2023]
Abstract
In the last half century, significant attention has been given to animal diseases; however, our understanding of disease processes and how to manage them at the livestock-wildlife interface remains limited. In this study, we conduct a systematic review of the scientific literature to evaluate the status of diseases at the livestock-wildlife interface in the United States. Specifically, the goals of the literature review were three fold: first to evaluate domestic animal diseases currently found in the United States where wildlife may play a role; second to identify critical issues faced in managing these diseases at the livestock-wildlife interface; and third to identify potential technical and policy strategies for addressing these issues. We found that of the 86 avian, ruminant, swine, poultry, and lagomorph diseases that are reportable to the World Organization for Animal Health (OIE), 53 are present in the United States; 42 (79%) of these have a putative wildlife component associated with the transmission, maintenance, or life cycle of the pathogen; and 21 (40%) are known to be zoonotic. At least six of these reportable diseases-bovine tuberculosis, paratuberculosis, brucellosis, avian influenza, rabies, and cattle fever tick (vector control)-have a wildlife reservoir that is a recognized impediment to eradication in domestic populations. The complex nature of these systems highlights the need to understand the role of wildlife in the epidemiology, transmission, and maintenance of infectious diseases of livestock. Successful management or eradication of these diseases will require the development of cross-discipline and institutional collaborations. Despite social and policy challenges, there remain opportunities to develop new collaborations and new technologies to mitigate the risks posed at the livestock-wildlife interface.
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Reisen WK. The contrasting bionomics of Culex mosquitoes in western North America. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2012; 28:82-91. [PMID: 23401947 DOI: 10.2987/8756-971x-28.4.82] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Mosquitoes in the genus Culex are the primary enzootic maintenance and bridge vectors of the North American encephalitides, now including West Nile virus. This review briefly summarizes the biology of three key vector species in western North America, Culex tarsalis, Cx. pipiens complex and Cx. stigmatosoma, focusing on the long history of research done in California. Topics reviewed include population genetic structure, larval ecology, autogeny, mating behavior, host-seeking behavior, host-selection patterns, and overwintering strategies. These attributes collectively have allowed the successful exploitation of anthropogenically altered ecosystems and enabled the role of these species as maintenance and bridge vectors of arboviruses.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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10
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THIEMANN TC, LEMENAGER DA, KLUH S, CARROLL BD, LOTHROP HD, REISEN WK. Spatial variation in host feeding patterns of Culex tarsalis and the Culex pipiens complex (Diptera: Culicidae) in California. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:903-16. [PMID: 22897051 PMCID: PMC3542768 DOI: 10.1603/me11272] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
West Nile virus (family Flaviviridae, genus Flavivirus, WNV) is now endemic in California across a variety of ecological regions that support a wide diversity of potential avian and mammalian host species. Because different avian hosts have varying competence for WNV, determining the blood-feeding patterns of Culex (Diptera: Culicidae) vectors is a key component in understanding the maintenance and amplification of the virus as well as tangential transmission to humans and horses. We investigated the blood-feeding patterns of Culex tarsalis Coquillett and members of the Culex pipiens L. complex from southern to northern California. Nearly 100 different host species were identified from 1,487 bloodmeals, by using the mitochondrial gene cytochrome c oxidase I (COI). Cx. tarsalis fed on a higher diversity of hosts and more frequently on nonhuman mammals than did the Cx. pipiens complex. Several WNV-competent host species, including house finch and house sparrow, were common bloodmeal sources for both vector species across several biomes and could account for WNV maintenance and amplification in these areas. Highly competent American crow, western scrub-jay and yellow-billed magpie also were fed upon often when available and are likely important as amplifying hosts for WNV in some areas. Neither species fed frequently on humans (Cx. pipiens complex [0.4%], Cx. tarsalis [0.2%]), but with high abundance, both species could serve as both enzootic and bridge vectors for WNV.
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Affiliation(s)
- T. C. THIEMANN
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California–Davis, Davis, CA 95616
| | - D. A. LEMENAGER
- Sutter-Yuba Mosquito and Vector Control District, P.O. Box 726, Yuba City, CA 95992
| | - S. KLUH
- Greater Los Angeles County Vector Control District, 12545 Florence Ave., Santa Fe Springs, CA 90670
| | - B. D. CARROLL
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California–Davis, Davis, CA 95616
| | - H. D. LOTHROP
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California–Davis, Davis, CA 95616
| | - W. K. REISEN
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California–Davis, Davis, CA 95616
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11
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Brown CR, O'Brien VA. Are Wild Birds Important in the Transport of Arthropod-borne Viruses? ACTA ACUST UNITED AC 2011. [DOI: 10.1525/om.2011.71.1.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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12
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Schuster G, Ebert EE, Stevenson MA, Corner RJ, Johansen CA. Application of satellite precipitation data to analyse and model arbovirus activity in the tropics. Int J Health Geogr 2011; 10:8. [PMID: 21255449 PMCID: PMC3038884 DOI: 10.1186/1476-072x-10-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 01/22/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Murray Valley encephalitis virus (MVEV) is a mosquito-borne Flavivirus (Flaviviridae: Flavivirus) which is closely related to Japanese encephalitis virus, West Nile virus and St. Louis encephalitis virus. MVEV is enzootic in northern Australia and Papua New Guinea and epizootic in other parts of Australia. Activity of MVEV in Western Australia (WA) is monitored by detection of seroconversions in flocks of sentinel chickens at selected sample sites throughout WA. Rainfall is a major environmental factor influencing MVEV activity. Utilising data on rainfall and seroconversions, statistical relationships between MVEV occurrence and rainfall can be determined. These relationships can be used to predict MVEV activity which, in turn, provides the general public with important information about disease transmission risk. Since ground measurements of rainfall are sparse and irregularly distributed, especially in north WA where rainfall is spatially and temporally highly variable, alternative data sources such as remote sensing (RS) data represent an attractive alternative to ground measurements. However, a number of competing alternatives are available and careful evaluation is essential to determine the most appropriate product for a given problem. RESULTS The Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 product was chosen from a range of RS rainfall products to develop rainfall-based predictor variables and build logistic regression models for the prediction of MVEV activity in the Kimberley and Pilbara regions of WA. Two models employing monthly time-lagged rainfall variables showed the strongest discriminatory ability of 0.74 and 0.80 as measured by the Receiver Operating Characteristics area under the curve (ROC AUC). CONCLUSIONS TMPA data provide a state-of-the-art data source for the development of rainfall-based predictive models for Flavivirus activity in tropical WA. Compared to ground measurements these data have the advantage of being collected spatially regularly, irrespective of remoteness. We found that increases in monthly rainfall and monthly number of days above average rainfall increased the risk of MVEV activity in the Pilbara at a time-lag of two months. Increases in monthly rainfall and monthly number of days above average rainfall increased the risk of MVEV activity in the Kimberley at a lag of three months.
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Affiliation(s)
- Grit Schuster
- Department of Spatial Sciences, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
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13
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Reisen WK, Wheeler SS, Garcia S, Fang Y. Migratory birds and the dispersal of arboviruses in California. Am J Trop Med Hyg 2010; 83:808-15. [PMID: 20889869 DOI: 10.4269/ajtmh.2010.10-0200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Each spring large numbers of neotropical migrants traversing the Pacific flyway pass through the Coachella Valley enroute to northern destinations, providing an opportunity to test the hypothesis that mosquito-borne encephalitis viruses are introduced annually into California by migratory birds. A total of 5,632 sera were collected from 43 species of migrants during spring (April-June), of which 34 (0.61%) comprised of 14 species tested positive by enzyme immunoassay; only 10 were confirmed by plaque reduction neutralization tests (PRNT). In addition, of 1,109 migrants comprised of 76 species that were reported dead by the public and necropsied, 126 (11%) were positive for West Nile virus (WNV) RNA; however, only three (0.7%) of 428 birds tested during the spring were positive. Limited experimental infection studies with WNV showed that Orange-crowned Warblers were highly susceptible and frequently died, whereas most Yellow Warblers survived. Our results indicated that birds entering California rarely exhibited a history of infection and that most birds probably became infected after entering California.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
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14
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Ghosh D, Guha R. Using a neural network for mining interpretable relationships of West Nile risk factors. Soc Sci Med 2010; 72:418-29. [PMID: 20950908 DOI: 10.1016/j.socscimed.2010.09.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 07/21/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022]
Abstract
The West Nile Virus (WNV) is an infectious disease spreading rapidly throughout the United States, causing illness among thousands of birds, animals, and humans. Yet, we only have a rudimentary understanding of how the mosquito-borne virus operates in complex avian-human environmental systems. The four broad categories of risk factors underlying WNV incidences are: environmental (temperature, precipitation, wetlands), socioeconomic (housing age), built-environment (catch basins, ditches), and existing mosquito abatement policies. This research first built a model incorporating the non-linear relationship between WNV incidences and hypothesized risk factors and second, identified important factor(s) whose management would result in effective disease prevention and containment. The research was conducted in the Metropolitan area of Minnesota, which had experienced significant WNV outbreaks from 2002. Computational neural network (CNN) modeling was used to understand the occurrence of WNV infected dead birds because of their ability to capture complex relationships with higher accuracy than linear models. Further a detailed interpretation technique, based on weights and biases of the network, provided a means for extracting relationships between risk factors and disease occurrence. Five risk factors: proximity to bogs, lakes, temperature, housing age, and developed medium density land cover class, were selected by the model. The detailed interpretation indicated that temperature, age of houses, and developed medium density land cover were positively related, and distance to bogs and lakes were negatively related to the incidence of WNV. This paper provides both applied and methodological contributions to the field of health geography. The relationships between the risk factors and disease occurrence could contribute to vector control strategies such as targeted insecticide spraying near bogs and lakes, mosquito control treatments for older houses, and extensive mapping, inspection, and treatments of catch basins. The proposed interpretation technique expanded the role of CNN models in health sciences as both predictive and explanatory tools.
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Affiliation(s)
- Debarchana Ghosh
- Kent State University, Geography, 413 McGilvery Hall, Department of Geography Kent State, Kent, OH 44242, United States.
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Barker CM, Johnson WO, Eldridge BF, Park BK, Melton F, Reisen WK. Temporal connections between Culex tarsalis abundance and transmission of western equine encephalomyelitis virus in California. Am J Trop Med Hyg 2010; 82:1185-93. [PMID: 20519621 DOI: 10.4269/ajtmh.2010.09-0324] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Definition of targets for vector control requires an understanding of the relationship between vector abundance and the intensity of arbovirus transmission. Using an extensive surveillance dataset with observations from sentinel chicken flocks and mosquito traps paired in time and space, hierarchical autoregressive logistic regression models were developed to predict the probability of seroconversion in chickens for western equine encephalomyelitis virus (WEEV) based on the relative abundance of the principal vector, Culex tarsalis. After adjustments for confounders, the abundance of Cx. tarsalis 29-42 d before the date of chicken sampling was credibly associated with the risk of WEEV transmission in both the Central and Coachella Valleys, and a doubling of relative Cx. tarsalis abundance was associated with a 58% increase in the odds of seroconversion. The critical time windows identified in our study highlight the need for surveillance of vector populations and forecasting models to guide proactive vector control measures before the detection of transmission to sentinel chickens.
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Affiliation(s)
- Christopher M Barker
- Center for Vectorborne Diseases, University of California, Old Davis Road, Davis, CA 95616, USA.
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Millins C, Reid A, Curry P, Drebot MA, Andonova M, Buck P, Leighton FA. Evaluating the use of house sparrow nestlings as sentinels for West Nile virus in Saskatchewan. Vector Borne Zoonotic Dis 2010; 11:53-8. [PMID: 20518643 DOI: 10.1089/vbz.2009.0235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study evaluated the use of house sparrow (Passer domesticus) nestlings as sentinels of West Nile virus (WNV) in the prairie grasslands of Saskatchewan. In the summer of 2006, 600 house sparrow nestlings were collected and pooled tissues tested by reverse transcriptase-polymerase chain reaction. All tested negative for WNV. During the same period, no WNV was detected by mosquito surveillance in the study area and 15 WNV-infected pools were collected from the nearby city of Estevan. Six percent of avian carcasses collected from Regina, a city 100 km from the study area in the same ecozone, were infected with WNV. In 2007, 200 house sparrow nestlings were collected and 4 tested positive for WNV, a prevalence of 2%. Ninety-seven house sparrow eggs were also collected and WNV antibodies were measured in the yolk. Seven eggs had measurable titers, a prevalence of 7.2%. Combined WNV surveillance showed high levels of WNV transmission in 2007; 112 WNV-infected mosquito pools were collected from nearby cities of Estevan and Weyburn, and the proportion of WNV infected avian carcasses from Regina was 78%. There were 1456 human cases of WNV in Saskatchewan in 2007, compared to 19 cases in 2006. The study concluded that house sparrow nestlings are not useful as an early warning of WNV circulation, or as a measure of the intensity of WNV activity in the prairie grasslands. Also, the study determined that maternally derived antibody did not have a significant limiting effect on WNV transmission to house sparrow nestlings in 2007, a year of epidemic WNV activity in the study area.
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Affiliation(s)
- Caroline Millins
- Department of Veterinary Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Diuk-Wasser MA, Molaei G, Simpson JE, Folsom-O'Keefe CM, Armstrong PM, Andreadis TG. Avian communal roosts as amplification foci for West Nile virus in urban areas in northeastern United States. Am J Trop Med Hyg 2010; 82:337-43. [PMID: 20134014 DOI: 10.4269/ajtmh.2010.09-0506] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
West Nile virus (WNV) perpetuates in an enzootic transmission cycle involving Culex mosquitoes and virus-competent avian hosts. In the northeastern United States, the enzootic vectors, Cx. pipiens and Cx. restuans, feed preferentially on American robins (Turdus migratorius), suggesting a key role for this bird species in the WNV transmission cycle. We examined the role of American robin communal roosts as virus amplification foci in greater New Haven, Connecticut. Robin communal roosts were located by radio tracking. After mid-August, when most robins were using the roosts, Cx. pipiens and Cx. restuans fed often on robins and were significantly more infected with WNV at communal roosts than at non-roosting sites. We also identified 6.4% human-derived blood meals in Aedes vexans in communal roosts. Our results indicate that communal roosts act as late-season amplification foci facilitating transmission to humans because of high infection rates, high abundance, and feeding patterns of enzootic and bridge vectors.
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Affiliation(s)
- Maria A Diuk-Wasser
- Division of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College Street, New Haven, CT 06520-8034, USA.
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Reisen WK, Carroll BD, Takahashi R, Fang Y, Garcia S, Martinez VM, Quiring R. Repeated West Nile virus epidemic transmission in Kern County, California, 2004-2007. JOURNAL OF MEDICAL ENTOMOLOGY 2009; 46:139-57. [PMID: 19198528 PMCID: PMC2729460 DOI: 10.1603/033.046.0118] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
West Nile virus (WNV) has remained epidemic in Kern County, CA, since its introduction in 2004 through 2007 when the human case annual incidence increased from 6-8 to 17 per 100,000, respectively. The 2007 increase in human infection was associated with contradicting surveillance indicators, including severe drought, warm spring but cool summer temperature anomalies, decreased rural and urban mosquito abundance but increased early season infection in urban Culex quinquefasciatus Say, moderate avian "herd immunity," and declines in the catch of competent (western scrub-jay and house finch) and noncompetent (California quail and mourning dove) avian species. The decline in these noncompetent avian hosts may have increased contact with competent avian hosts and perhaps humans. The marked increase in home foreclosures and associated neglected swimming pools increased urban mosquito production sites, most likely contributing to the urban mosquito population and the WNV outbreak within Bakersfield. Coalescing five surveillance indicators into a risk assessment score measured each half month provided 2- to 6-wk early warning for emergency planning and was followed consistently by the onset of human cases after reaching epidemic conditions. St. Louis encephalitis virus (SLEV) antibody was detected rarely in wild birds but not mosquitoes or sentinel chickens, indicating that previously infected birds were detected in Kern County, but SLEV reintroduction was not successful. In contrast, western equine encephalitis virus (WEEV) was detected during 3 of 5 yr in Culex tarsalis Coquillett, sentinel chickens, and wild birds, but failed to amplify to levels where tangential transmission was detected in Aedes mosquitoes or humans. A comparison of transmission patterns in Kern County to Coachella Valley in the southeastern desert of California showed the importance of mosquito phenology and spatial distribution, corvids, or other avian "super spreaders" and anthropogenic factors in WNV epidemiology.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Old Davis Rd., Davis, CA 95616, USA.
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Reisen WK, Lothrop HD, Wheeler SS, Kennsington M, Gutierrez A, Fang Y, Garcia S, Lothrop B. Persistent West Nile virus transmission and the apparent displacement St. Louis encephalitis virus in southeastern California, 2003-2006. JOURNAL OF MEDICAL ENTOMOLOGY 2008; 45:494-508. [PMID: 18533445 PMCID: PMC2435167 DOI: 10.1603/0022-2585(2008)45[494:pwnvta]2.0.co;2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
West Nile virus (family Flaviviridae, genus Flavivirus, WNV) invaded the Colorado Desert biome of southern California during summer 2003 and seemed to displace previously endemic St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV, an antigenically similar Flavivirus in the Japanese encephalitis virus serocomplex). Western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV), an antigenically distinct Alphavirus, was detected during 2005 and 2006, indicating that conditions were suitable for encephalitis virus introduction and detection. Cross-protective "avian herd immunity" due to WNV infection possibly may have prevented SLEV reintroduction and/or amplification to detectable levels. During 2003-2006, WNV was consistently active at wetlands and agricultural habitats surrounding the Salton Sea where Culex tarsalis Coquillett served as the primary enzootic maintenance and amplification vector. Based on published laboratory infection studies and the current seroprevalence estimates, house sparrows, house finches, and several Ardeidae may have been important avian amplifying hosts in this region. Transmission efficiency may have been dampened by high infection rates in incompetent avian hosts, including Gamble's quail, mourning doves, common ground doves, and domestic pigeons. Early season WNV amplification and dispersal from North Shore in the southeastern portion of the Coachella Valley resulted in sporadic WNV incursions into the urbanized Upper Valley near Palm Springs, where Culex pipiens quinquefasciatus Say was the primary enzootic and bridge vector. Although relatively few human cases were detected during the 2003-2006 period, all were concentrated in the Upper Valley and were associated with high human population density and WNV infection in peridomestic populations of Cx. p. quinquefasciatus. Intensive early mosquito control during 2006 seemed to interrupt and delay transmission, perhaps setting the stage for the future reintroduction of SLEV.
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Affiliation(s)
- William K Reisen
- Arbovirus Research Unit, Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Old Davis Rd., Davis, CA 95616, USA.
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Ezenwa VO, Milheim LE, Coffey MF, Godsey MS, King RJ, Guptill SC. Land cover variation and West Nile virus prevalence: patterns, processes, and implications for disease control. Vector Borne Zoonotic Dis 2007; 7:173-80. [PMID: 17627435 DOI: 10.1089/vbz.2006.0584] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Identifying links between environmental variables and infectious disease risk is essential to understanding how human-induced environmental changes will effect the dynamics of human and wildlife diseases. Although land cover change has often been tied to spatial variation in disease occurrence, the underlying factors driving the correlations are often unknown, limiting the applicability of these results for disease prevention and control. In this study, we described associations between land cover composition and West Nile virus (WNV) infection prevalence, and investigated three potential processes accounting for observed patterns: (1) variation in vector density; (2) variation in amplification host abundance; and (3) variation in host community composition. Interestingly, we found that WNV infection rates among Culex mosquitoes declined with increasing wetland cover, but wetland area was not significantly associated with either vector density or amplification host abundance. By contrast, wetland area was strongly correlated with host community composition, and model comparisons suggested that this factor accounted, at least partially, for the observed effect of wetland area on WNV infection risk. Our results suggest that preserving large wetland areas, and by extension, intact wetland bird communities, may represent a valuable ecosystem-based approach for controlling WNV outbreaks.
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Affiliation(s)
- Vanessa O Ezenwa
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA.
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21
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Gibbs SEJ, Allison AB, Yabsley MJ, Mead DG, Wilcox BR, Stallknecht DE. West Nile virus antibodies in avian species of Georgia, USA: 2000-2004. Vector Borne Zoonotic Dis 2007; 6:57-72. [PMID: 16584328 DOI: 10.1089/vbz.2006.6.57] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
West Nile virus (WNV) was first isolated in the state of Georgia in the summer of 2001. As amplifying hosts of WNV, avian species play an important role in the distribution and epidemiology of the virus. The objective of this study was to identify avian species that are locally involved as potential amplifying hosts of WNV and can serve as indicators of WNV transmission over the physiographic and land use variation present in the southeastern United States. Avian serum samples (n=14,077) from 83 species of birds captured throughout Georgia during the summers of 2000-2004 were tested by a plaque reduction neutralization test for antibodies to WNV and St. Louis encephalitis virus. Over the 5-year period, WNV-neutralizing antibodies were detected in 869 (6.2%) samples. The WNV seroprevalence increased significantly throughout the study and was species dependent. The highest antibody prevalence rates were detected in rock pigeons (Columba livia), northern cardinals (Cardinalis cardinalis), common ground doves (Columbina passerina), grey catbirds (Deumetella carolinensis), and northern mockingbirds (Mimus polyglottos). Northern cardinals, in addition to having high geometric mean antibody titers and seroprevalence rates, were commonly found in all land use types and physiographic regions. Rock pigeons, common ground doves, grey catbirds, and northern mockingbirds, although also having high seroprevalence rates and high antibody titers against WNV, were more restricted in their distribution and therefore may be of more utility when attempting to assess exposure rates in specific habitat types. Of all species tested, northern cardinals represent the best potential avian indicator species for widespread serologic-based studies of WNV throughout Georgia due to their extensive range, ease of capture, and high antibody rates and titers. Due to the large geographic area covered by this species, their utility as a WNV sentinel species may include most of the eastern United States.
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Affiliation(s)
- Samantha E J Gibbs
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, USA.
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Reisen WK, Martinez VM, Fang Y, Garcia S, Ashtari S, Wheeler SS, Carroll BD. Role of California (Callipepla californica) and Gambel's (Callipepla gambelii) quail in the ecology of mosquito-borne encephalitis viruses in California, USA. Vector Borne Zoonotic Dis 2007; 6:248-60. [PMID: 16989564 DOI: 10.1089/vbz.2006.6.248] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gambel's and California quail were infected repeatedly whenever western equine encephalomyelitis virus (WEEV), St. Louis encephalitis virus (SLEV), and (WNV) West Nile virus were active during summer in California. The timing of virus appearance and quail infection coincided well with the appearance of chicks in nature, leading us to hypothesize that large coveys containing these non-immune birds could be important in focal virus amplification in rural settings. However, experimental infection studies with chicks, juveniles, and adults of both quail species using sympatric strains of WEEV, SLEV, and WNV indicated that only immature birds were competent hosts for WEEV, producing viremias sufficiently elevated to efficiently infect Culex tarsalis mosquitoes. Quail were less competent hosts for WNV and were incompetent for SLEV. Large populations of quail that frequently are infected with SLEV or WNV, but produce low to moderate viremias, may serve as dead end hosts for these viruses. Due to their abundance and repeated infection, these birds may attenuate virus amplification in rural areas of California and possibly could be one reason why WNV epidemics seem to occur more frequently in urban and periurban than in rural landscapes.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
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Reisen WK, Fang Y. Does feeding on infected mosquitoes (Diptera: Culicidae) enhance the role of song sparrows in the transmission of arboviruses in California? JOURNAL OF MEDICAL ENTOMOLOGY 2007; 44:316-9. [PMID: 17427703 DOI: 10.1603/0022-2585(2007)44[316:dfoimd]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Song sparrows, Melopiza melodia, inoculated subcutaneously with either western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV) or West Nile virus (family Flaviviridae, genus Flavivirus, WNV) developed elevated viremias, and they were considered to be competent experimental hosts for both viruses. However, birds that ingested from three to 20 mosquitoes containing comparable amounts of either WEEV or WNV failed to become infected, indicating limited oral susceptibility. Comparatively few field-collected birds had antibodies against either WEEV or WNV, indicating that this species was infrequently bitten by infectious mosquitoes in nature and probably was of limited importance in viral amplification.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases and Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Chvala S, Bakonyi T, Hackl R, Hess M, Nowotny N, Weissenböck H. Limited pathogenicity of Usutu virus for the domestic chicken (Gallus domesticus). Avian Pathol 2007; 34:392-5. [PMID: 16236570 DOI: 10.1080/03079450500268500] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In summer 2001, Usutu virus (USUV), a mosquito-borne flavivirus, was isolated for the first time in Europe during a mortality incident among Eurasian blackbirds (Turdus merula) in Austria. Chickens are frequently used as sentinel animals for arbovirus surveillance systems. In the present study, the pathogenicity of USUV for specific pathogen free chickens was investigated. Ten 2-week-old chickens were inoculated intravenously with 0.1 ml inoculum containing 10(3) median (50%) tissue culture infectious dose of USUV strain Vienna 2001-blackbird (939/01). Clinical signs, viraemia, gross and microscopic lesions, contact transmission and immunological response were evaluated. No clinical signs were observed in the USUV-inoculated animals during the experimental period. Pathological examination showed moderate splenomegaly and follicular infiltrates in the liver of several inoculated animals. Mild non-suppurative encephalitis was observed in the brain tissue of one virus-inoculated chicken examined 7 days post inoculation (d.p.i.). USUV nucleic acid was detected by reverse-transcriptase polymerase chain reaction in the organs of six inoculated chickens, although immunohistochemistry for flavivirus antigen was negative in all tissues from all chickens. Virus shedding was shown in three inoculated birds by detecting USUV RNA in cloacal swabs of two chickens at 5 d.p.i., and in the cloacal and pharyngeal swabs of one chicken at 7 d.p.i. Based on detection of viral RNA in peripheral blood mononuclear cells, viraemia was detected only in two chickens (at 7 d.p.i.). Only one of the inoculated chickens developed an antibody response. There was no evidence of virus transmission to chickens kept in contact with inoculated birds. No USUV was isolated from in-contact birds and all in-contact and control animals lacked USUV-specific antibodies. The present data suggest that domestic chickens are not at risk of developing clinical disease following USUV infection and that chickens are unlikely to be useful for sentinel purposes in USUV surveillance programmes.
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Affiliation(s)
- S Chvala
- Department of Pathobiology, Institute of Pathology and Forensic Veterinary Medicine, Budapest, Hungary
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25
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Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related with animal health and welfare risks associated with the import of wild birds other than poultry into the European Union. EFSA J 2006; 4:410. [PMID: 32313576 PMCID: PMC7163484 DOI: 10.2903/j.efsa.2006.410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
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McCluskey BJ, Burgess B, Glover J, Kinde H, Hietala S. Use of sentinel chickens to evaluate the effectiveness of cleaning and disinfection procedures in noncommercial poultry operations infected with exotic Newcastle disease virus. J Vet Diagn Invest 2006; 18:296-9. [PMID: 16789722 DOI: 10.1177/104063870601800313] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The use of sentinel chickens in establishing the negative status of commercial poultry flocks depopulated due to exotic Newcastle disease (END) is considered to be an economically beneficial process. However, the costs and benefits of using sentinel chickens in noncommercial operations are in question. The objective of this study was to use sentinel chickens to evaluate whether adequate cleaning and disinfection coupled with an appropriate time period without susceptible poultry species on the premises would eliminate END virus from a noncommercial poultry operation and preclude the need for placement of sentinels in previously infected operations before declaring them free of virus. Noncommercial poultry operations were selected from the 2002 to 2003 END outbreak database. Operations included in the study had one or more isolations of END virus (ENDV) from cloacal or oropharyngeal swabs of birds on the premises. A total of 546 birds were placed on 53 premises. All sentinel birds sampled after placements were negative by virus detection methods and serologic tests. Results of this study indicate that time and the application of appropriate cleaning and disinfection procedures will adequately mitigate the risk of viable virus persisting in noncommercial poultry operations. In the future, this information may eliminate the need for sentinel bird placement to ensure virus free status of premises before repopulation, thereby decreasing the costs of END eradication.
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Affiliation(s)
- Brian J McCluskey
- USDA Centers for Epidemiology and Animal Health, Fort Collins, CO 80526-8117, USA
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Reisen WK, Wheeler SS, Yamamoto S, Fang Y, Garcia S. Nesting Ardeid colonies are not a focus of elevated West Nile virus activity in southern California. Vector Borne Zoonotic Dis 2006; 5:258-66. [PMID: 16187895 DOI: 10.1089/vbz.2005.5.258] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A large nesting colony of Ardeid birds at the Finney-Ramer Wildlife Refuge in Imperial County, California, did not appear to be a focus of West Nile virus (WNV) amplification during the summer of 2004. Blood samples taken during June and July from 155 nestlings of four species of Ardeid birds (cattle egrets, black-crowned night herons, great egrets, and snowy egrets) and five nestling double-crested cormorants yielded a single WNV isolation from a 3-week-old cattle egret. Antibody was detected by enzyme immunoassay from 20 nestlings (13%), 14 (70%) of which were confirmed as positive by plaque reduction neutralization test (PRNT). However, titration end points against WNV and St. Louis encephalitis virus (SLEV) were similar precluding viral identification. The grouping of positives within few nests, highest PRNT titers in youngest birds (<1 weeks of age), the decline of titer with nestling age, and the lack of antibody specificity indicated that antibody may have been acquired maternally and did not represent new infections. Infection rates in Culex tarsalis mosquitoes collected near the Ardeid colony at Ramer Lake (3.1 per 1,000) were statistically similar to rates estimated at the nearby Wister Unit wetlands (5.3 per 1,000) that lacked an Ardeid nesting colony. Black-crowned night heron nestlings experimentally infected with the NY99 strain of WNV produced viremias >5 log10 plaque forming units (PFU)/mL and were considered moderately competent hosts, whereas cattle egret nestlings had viremias that remained <5 log10 PFU/mL and were incompetent hosts.
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Affiliation(s)
- W K Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
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Gibbs SEJ, Hoffman DM, Stark LM, Marlenee NL, Blitvich BJ, Beaty BJ, Stallknecht DE. Persistence of antibodies to West Nile virus in naturally infected rock pigeons (Columba livia). CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:665-7. [PMID: 15879030 PMCID: PMC1112075 DOI: 10.1128/cdli.12.5.665-667.2005] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Wild caught rock pigeons (Columba livia) with antibodies to West Nile virus were monitored for 15 months to determine antibody persistence and compare results of three serologic techniques. Antibodies persisted for the entire study as detected by epitope-blocking enzyme-linked immunosorbent assay and plaque reduction neutralization test. Maternal antibodies in squabs derived from seropositive birds persisted for an average of 27 days.
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Affiliation(s)
- Samantha E J Gibbs
- Wildlife Health Building, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-4393, USA.
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29
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Reisen WK, Chiles R, Martinez V, Fang Y, Green E, Clark S. Effect of dose on house finch infection with western equine encephalomyelitis and St. Louis encephalitis viruses. JOURNAL OF MEDICAL ENTOMOLOGY 2004; 41:978-981. [PMID: 15535631 DOI: 10.1603/0022-2585-41.5.978] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
House finches, Carpodacus mexicanus, were experimentally infected with high and standard doses of western equine encephalomyelitis virus (WEEV) or St. Louis encephalitis virus (SLEV) to determine whether high doses would produce an elevated viremia response and a high frequency of chronic infections. Finches inoculated with approximately100,000 plaque forming units (PFU) of WEEV or SLEV produced viremia and antibody responses similar to those in finches inoculated with approximately 100 PFU of WEEV or 1000 PFU of SLEV, the approximate quantities of virus expectorated by blood-feeding Culex tarsalis Coquillett. Infected finches were held through winter and then necropsied. Only one finch inoculated with the high dose of SLEV developed a chronic infection. Our data indicated that elevated infectious doses of virus may not increase the viremia level or the frequency of chronic infection in house finches.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Mahmood F, Chiles RE, Fang Y, Barker CM, Reisen WK. Role of nestling mourning doves and house finches as amplifying hosts of St. Louis encephalitis virus. JOURNAL OF MEDICAL ENTOMOLOGY 2004; 41:965-972. [PMID: 15535629 DOI: 10.1603/0022-2585-41.5.965] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nestling mourning doves and house finches produced elevated viremias after inoculation with 2-3 log10 plaque-forming units (PFU) of St Louis encephalitis (SLE) virus and infected 67 and 70% of Culex tarsalis Coquillett that engorged upon them, respectively. Mosquito infection rates as well as the quantity of virus produced after extrinsic incubation increased as a function of the quantity of virus ingested and peaked during days 3-5 postinoculation in mourning doves and days 2-4 in house finches. Only female Cx. tarsalis with body titers > or = 4.6 log10 PFU were capable of transmitting virus. Overall, 38% of females infected by feeding on mourning doves and 22% feeding on house finches were capable of transmission. The quantity of virus expectorated was variable, ranging from 0.8 to 3.4 log10 PFU and was greatest during periods when avian viremias were elevated. Our data indicated that nestling mourning doves and house finches were competent hosts for SLE virus and that the quantity of virus ingested from a viremic avian host varies during the course of the infection and determines transmission rates by the mosquito vector.
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Affiliation(s)
- Farida Mahmood
- Center for Vectorborne Diseases, School of Veterinary Medicine, Old Davis Road, University of California, Davis, California 95616, USA
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Reisen W, Lothrop H, Chiles R, Madon M, Cossen C, Woods L, Husted S, Kramer V, Edman J. West Nile virus in California. Emerg Infect Dis 2004; 10:1369-78. [PMID: 15496236 PMCID: PMC3320391 DOI: 10.3201/eid1008.040077] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
West Nile virus (WNV) was first isolated in California during July 2003 from a pool of Culex tarsalis collected near El Centro, Imperial County. WNV transmission then increased and spread in Imperial and Coachella Valleys, where it was tracked by isolation from pools of Cx. tarsalis, seroconversions in sentinel chickens, and seroprevalence in free-ranging birds. WNV then dispersed to the city of Riverside, Riverside County, and to the Whittier Dam area of Los Angeles County, where it was detected in dead birds and pools of Cx. pipiens quinquefasciatus. By October, WNV was detected in dead birds collected from riparian corridors in Los Angeles, west to Long Beach, and through inland valleys south from Riverside to San Diego County. WNV was reported concurrently from Arizona in mid-August and from Baja, Mexico, in mid-November. Possible mechanisms for virus introduction, amplification, and dispersal are discussed.
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Nelson DM, Gardner IA, Chiles RF, Balasuriya UB, Eldridge BF, Scott TW, Reisen WK, Maclachlan NJ. Prevalence of antibodies against Saint Louis encephalitis and Jamestown Canyon viruses in California horses. Comp Immunol Microbiol Infect Dis 2004; 27:209-15. [PMID: 15001316 DOI: 10.1016/j.cimid.2003.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2003] [Indexed: 11/28/2022]
Abstract
Jamestown Canyon (JC) and Saint Louis encephalitis (SLE) viruses are mosquito-transmitted viruses that have long been present in California. The objective of this study was to determine the seroprevalence of these two viruses in horses prior to the introduction of West Nile (WN) virus. Approximately 15% of serum samples collected in 1998 from 425 horses on 44 equine operations horses throughout California had serum antibodies to JC virus, whereas antibodies were not detected to SLE virus. The results indicate that horses in California were commonly infected prior to 1998 with mosquito-transmitted Bunyaviruses that are identical or closely related to JC virus, but not with SLE virus. The different seroprevalence of SLE and JC viruses in horses likely reflects the unique ecology of each virus, and it is predicted that WN virus will have a wider distribution in California than closely related SLE virus.
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Affiliation(s)
- Dana M Nelson
- Animal and Plant Health Inspection Service, Veterinary Services, U.S. Department of Agriculture, California and Nevada Area Office, 9850 Micron Avenue, Suite E, Sacramento, CA 95827, USA
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Reisen WK, Chiles RE, Martinez VM, Fang Y, Green EN. Encephalitis virus persistence in California birds: experimental infections in mourning doves (Zenaidura macroura). JOURNAL OF MEDICAL ENTOMOLOGY 2004; 41:462-466. [PMID: 15185951 DOI: 10.1603/0022-2585-41.3.462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
After-hatching and hatching year, mourning doves were infected by inoculation with either western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses; some birds in each group also were treated with the immunosuppressant cyclophosphamide before and during infection. Cyclophosphamide treatment significantly increased the WEE viremia but did not alterthe antibody response. In contrast, cyclophosphamide-treated and -untreated doves did not develop a detectable SLE viremia but became antibody positive. Antibody peaked at 10 wk after inoculation for both viruses and remained detectable in most birds throughout the 26-wk study. When treated with cyclophosphamide the following spring, birds did not relapse and develop a detectable viremia. Previously infected birds were protected when challenged with conspecific virus (i.e., none produced a detectable viremia), but there was no anamnestic antibody response to reinfection. In agreement with our failure to detect relapses, all birds were negative for viral RNA when sera, spleen, lung, and kidney tissues were tested by reverse transcriptase-polymerase chain reaction after necropsy. Our results indicated that adult mourning doves were an incompetent host for SLE virus and probably do not serve as a suitable overwintering or dispersal host for either WEE and SLE viruses.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, School of Veterinary Medicine, Davis, University of California, CA 95616, USA.
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Affiliation(s)
- William K Reisen
- Arbovirus Field Station Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
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Reisen WK, Chiles RE, Martinez VM, Fang Y, Green EN. Experimental infection of California birds with western equine encephalomyelitis and St. Louis encephalitis viruses. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:968-982. [PMID: 14765678 DOI: 10.1603/0022-2585-40.6.968] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A total of 27 bird species from the San Joaquin and Coachella valleys of California were inoculated subcutaneously with sympatric strains of western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses. Overall, 133 of 164 birds inoculated with WEE virus developed a viremia detected by plaque assay; significantly greater than 72 of 163 birds inoculated with SLE virus. Host competence was calculated as the average number of days that each avian species had a viremia > or = 2 log10 plaque-forming units per 0.1 ml, the threshold for infecting susceptible Culex tarsalis Coquillett, the primary vector of these viruses in California. Eleven of 20 species inoculated with WEE virus had a value > or = 1 and were considered to be competent hosts, whereas only six of 22 species inoculated with SLE virus had a value > or = 1. Overall, 133 of 164 birds inoculated with WEE virus and 105 of 163 inoculated with SLE virus produced antibody detectable by enzyme immunoassay and/or plaque reduction neutralization test. Six birds infected with WEE virus (one house finch, three mourning doves, one Brewer's sparrow, and one white-crowned sparrow) and nine birds infected with SLE virus (two house finches, three white-crowned sparrows, one song sparrow, two Western scrub-jays, and one orange crowned warbler) contained viral RNA detected by reverse transcription-polymerase chain reaction at necropsy > 6 wk postinoculation; infectious WEE and SLE viruses were only recovered from three mourning doves and an orange-crowned warbler, respectively, after blind passage in mosquito cells. Our study indicated that birds with elevated field antibody prevalence rates may not be the most competent hosts for encephalitis viruses and that relatively few birds developed chronic infections that could be important in virus persistence and dispersal.
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Affiliation(s)
- W K Reisen
- Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Old Davis Road, Davis, CA 95616, USA.
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Barker CM, Reisen WK, Kramer VL. California state Mosquito-Borne Virus Surveillance and Response Plan: a retrospective evaluation using conditional simulations. Am J Trop Med Hyg 2003; 68:508-18. [PMID: 12812335 DOI: 10.4269/ajtmh.2003.68.508] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The California Mosquito-Borne Virus Surveillance and Response Plan recently was developed to provide a semi-quantitative means for assessing risk for western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses and to provide intervention guidelines for mosquito control and public health agencies during periods of heightened risk for human infection. West Nile virus recently has arrived in California, and the response plan also will provide a baseline for assessing the risk for human and equine infection with this virus. In the response plan, overall risk is calculated by averaging risk due to 1) environmental conditions, 2) adult mosquito vector abundance, 3) vector infection rates, 4) sentinel chicken seroconversion rates, 5) equine cases (for WEE), 6) human cases, and 7) the proximity of virus activity to populated areas. Overall risk is categorized into three levels: normal season, emergency planning, or epidemic conditions. We evaluated this response plan using historical data from years with no, enzootic, and epidemic activity of WEE and SLE in several areas of California to determine whether calculated risk levels approximated actual conditions. Multiple methods of risk calculation were considered for both viruses. Assessed risk based on cumulative temperature, rainfall, and runoff levels over the entire season provided more or equally accurate assessments than biweekly assessments based solely on the previous half-month. For WEE, during years with enzootic activity or early-season periods of years with WEE epidemic activity, combining horse and human cases as a single risk factor improved the model's ability to forecast pending WEE activity, but separating the two factors allowed a better indication of WEE activity during epidemics and periods with no activity. For SLE, assignment of higher risk to drier conditions as measured by rainfall and runoff yielded the most accurate representation of actual virus activity during all recent study periods.
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Affiliation(s)
- Christopher M Barker
- Center for Vector-Borne Diseases, School of Veterinary Medicine, University of California, Davis, California, USA.
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Reisen WK, Chiles RE, Green EN, Fang Y, Mahmood F. Previous infection protects house finches from re-infection with St. Louis encephalitis virus. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:300-305. [PMID: 12943108 DOI: 10.1603/0022-2585-40.3.300] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Antibody titers against St. Louis encephalitis virus (SLE) measured by a plaque reduction neutralization test (PRNT) decreased rapidly in house finches (Capodacus mexicanus) after initial infection, whereas antibodies measured by enzyme immunoassay (EIA) remained detectable in all birds for the length of the experiment, indicating long-term persistence and greater assay sensitivity of the EIA. After 52 wk, birds were challenged by subcutaneous inoculation with the same strain of SLE virus. Virus was not detected for 1-4 d postchallenge in blood samples tested by plaque assay and RT-PCR or by xenodiagnosis in Culex tarsalis fed concurrently and then held for 11 d at 26 degrees C. Virus was detected by all three methods in control birds infected concurrently for the first time. Challenge with SLE produced a rapid and marked ananmestic rise in both neutralizing and EIA antibody titers that exceeded the primary response in the same birds or in concurrently inoculated control birds. At necropsy 4 wk postchallenge, 3 of 7 challenged and 1 of 2 positive control birds were chronically infected, with viral RNA detected by RT-PCR in brain, spleen, lung, and/or kidney tissues. Our results indicated that persistence of protective antibody prevents reinfection during the following season and may prevent the recrudescence of infectious virus in chronically infected birds.
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Affiliation(s)
- W K Reisen
- Arbovirus Research Unit, Center for Vector borne Diseases, School of Veterinary Medicine, University of California, Davis 95616, USA.
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Reisen WK, Chiles RE, Green EN, Fang Y, Mahmood F, Martinez VM, Laver T. Effects of immunosuppression on encephalitis virus infection in the house finch, Carpodacus mexicanus. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:206-214. [PMID: 12693850 DOI: 10.1603/0022-2585-40.2.206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Immunosuppression of house finches was attempted by blood feeding Culex tarsalis Coquillett mosquitoes or by injecting birds with the corticosteroid dexamethasone or the immunosuppressant drug cyclophosphamide before and after inoculation with western equine encephalomyelitis or St. Louis encephalitis viruses. Mosquito bites (8-37 females blood feeding on each bird over a 3-d period) did not enhance the viremia response or increase the frequency of chronic infection. In contrast, dexamethasone and cyclophosphamide enhanced the amplitude and duration of the viremia response, but had no consistent effect on the antibody responses as measured by enzyme immunoassay or plaque reduction neutralization assay. Elevated viremias were followed by increases in the frequency of chronic infections with St. Louis encephalitis, but not western equine encephalomyelitis. Immunosuppression may provide a useful tool to study the chronic infection process of flaviviruses in vertebrates.
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Affiliation(s)
- William K Reisen
- Arbovirus Research Unit, Center for Vector-borne Disease Research, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Reisen WK, Lothrop HD, Chiles RE, Cusack R, Green EGN, Fang Y, Kensington M. Persistence and amplification of St. Louis encephalitis virus in the Coachella Valley of California, 2000-2001. JOURNAL OF MEDICAL ENTOMOLOGY 2002; 39:793-805. [PMID: 12349864 DOI: 10.1603/0022-2585-39.5.793] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The introduction of a St. Louis encephalitis virus (SLE) genotype new to southeastern California during 2000 was followed by focal enzootic amplification in the Coachella Valley that was detected by seroconversions of 29 sentinel chickens in five of nine flocks of 10 chickens each, isolations of virus from 30 of 538 pools of 50 Culex tarsalis Coquillett females, and collection of 30 positive sera from 2,205 wild birds. This SLE strain over wintered successfully and then amplified during the summer of 2001, with 47 sentinel seroconversions in eight of nine flocks, 70 virus isolations from 719 pools of Cx. tarsalis and Cx. p. quinquefasciatus Say, and 40 positive sera from 847 wild birds. Human illness was not detected by passive case surveillance, despite issuance of a health alert during 2001. Virus amplification during both years was associated with above average temperatures conducive for extrinsic incubation and below average precipitation during spring associated with below average vector abundance. Seroconversions by sentinel chickens provided the timely detection of virus activity, with initial conversions detected before positive mosquito pools or wild bird infections. Vertical infection was not detected among Cx. tarsalis adults reared from immatures collected during the fall-winter of 2000, even though SLE over wintered successfully in this area. Early seroconversions by a sentinel chicken during February 2001 and a recaptured Gambel's quail in April 2001 provided evidence for transmission during winter and spring when ambient temperatures averaged below 17 degrees C, the threshold for SLE replication.
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Affiliation(s)
- W K Reisen
- Center for Vector-borne Disease Research, School of Veterinary Medicine, University of California, Davis 95616, USA.
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Reisen WK, Kramer LD, Chiles RE, Wolfe TM, Green EGN. Simulated overwintering of encephalitis viruses in diapausing female Culex tarsalis (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2002; 39:226-233. [PMID: 11931262 DOI: 10.1603/0022-2585-39.1.226] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Female Culex tarsalis Coquillett in reproductive diapause were infected per os or by intrathoracic inoculation with western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses during "fall," maintained over a simulated "winter," and then tested for virus infection and transmission in vitro and in vivo after "vernal" termination. Exposure of F1 progeny of field-collected females to cool temperatures and short daylength produced females in reproductive diapause that were reluctant to imbibe infectious virus from pledgets soaked with suspensions of virus, blood and sucrose (2.5% by volume). Those infected per os maintained virus at very low or undetectable titers. Some females that originally tested negative for WEE by plaque assay on Vero cell culture tested positive by reverse transcriptase-polymerase chain reaction (RT-PCR) and by Vero cell culture after passage in mosquito cells. Few females became infected orally with SLE, but these infected females developed elevated titers. Females inoculated with SLE retained their infection through winter and then transmitted readily in vitro and in vivo. Feeding on a vertebrate host after diapause termination significantly increased the titer of SLE in previously infected females. These experiments simulated how infections acquired either horizontally or vertically may provide mechanisms for WEE and SLE overwintering. Attempts to detect infected females during winter following a summer with enzootic WEE activity were negative by both RT-PCR and plaque assay.
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Affiliation(s)
- William K Reisen
- Arbovirus Research Unit, Center for Vector-borne Disease Research, School of Veterinary Medicine, University of California, Davis 95616, USA.
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Abstract
Captive and free-ranging birds have been used for decades as living sentinels in arbovirus surveillance programs. This review summarizes information relevant to selecting sentinel bird species for use in surveillance of West Nile (WN) virus. Although experience using avian sentinels for WN virus surveillance is limited, sentinels should be useful for both detecting and monitoring WN virus transmission; however, sentinel bird surveillance systems have yet to be adequately tested for use with the North American strain of WN virus. Captive chickens are typically used for arbovirus surveillance, but other captive species may be used as well. Serosurvey and experimental infection data suggest that both chickens and pigeons show promise as useful captive sentinels; both species were naturally exposed during the epizootics in New York City, 1999-2000, and both species develop antibodies after infection without becoming highly infectious to Culex pipiens vectors. Wild bird species that should be targeted for use as free-ranging sentinels include house sparrows and pigeons. The ideal wild bird should be determined locally on the basis of seroprevalence studies. Interpreting serological data generated from studies using free-ranging sentinel birds is complex, however. Sentinel bird monitoring sites should be selected in enzootic transmission foci. Several years of observation may be required for selection of effective sentinel monitoring sites.
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Affiliation(s)
- N Komar
- Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, USA.
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Komar N, Panella NA, Boyce E. Exposure of Domestic Mammals to West Nile Virus during an Outbreak of Human Encephalitis, New York City, 1999. Emerg Infect Dis 2001. [DOI: 10.3201/eid0704.017424] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Nicholas Komar
- Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
| | | | - Edward Boyce
- New York City Department of Health, New York, New York, USA
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Reisen WK, Kramer LD, Chiles RE, Green EG, Martinez VM. Encephalitis virus persistence in California birds: preliminary studies with house finches. JOURNAL OF MEDICAL ENTOMOLOGY 2001; 38:393-399. [PMID: 11372964 DOI: 10.1603/0022-2585-38.3.393] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Field-collected house finches of mixed sex and age were infected experimentally with either western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses during the summer or fall of 1998 and maintained over the winter under ambient conditions. To detect natural relapse during the spring, 32 birds were bled weekly from February through June 1999, and then necropsied 1 yr after infection to detect chronic infections using a reverse transcription polymerase chain reaction (RT-PCR). After 10 mo, 13/14 surviving birds previously infected with WEE were antibody positive by enzyme immunoassay (EIA), and 11/14 had plaque reduction neutralization test (PRNT) antibody titers >1:20, whereas only of 8/13 birds previously infected with SLE were positive by EIA and all had PRNT titers <1:20. When necropsied, 1/14 and 1/13 birds had WEE and SLE RT-PCR positive lung or spleen tissue, respectively; blood, brain, and liver tissues were negative as were all previous blood samples. All tissues from these birds including weekly blood samples tested negative for infectious virus by plaque assay on Vero cell culture. To determine if persistent antibody was protective, birds infected initially with WEE or SLE in November 1998 were challenged 6 mo later with homologous virus. WEE antibody persisted well (5/6 birds remained PRNT positive before challenge) and remained protective, because 0/6 birds were viremic after challenge. In contrast, SLE antibody decayed rapidly (0/6 birds remained PRNT positive before challenge) and was not protective, because 3/6 birds developed an ephemeral viremia on day 1 after infection (mean titer, 10(2.73) plaque forming units/0.1 ml). When necropsied 7 wk after challenge, 1/110 birds infected with WEE and 1/10 birds infected with SLE exhibited an RT-PCR positive spleen, despite the fact that both birds had PRNT antibody titers >1:40 at this time. To determine if immunosuppression would cause a chronic infection to relapse, eight birds initially infected with either WEE or SLE were treated with cyclophosphamide and then tested repeatedly for viremia; all samples were negative for virus by plaque assay. Collectively, our results indicated that a low percentage of birds experimentally infected with WEE or SLE developed chronic infections in the spleen or lung that could be detected by RT-PCR, but not by plaque assay. Birds did not appear to relapse naturally or after immunosuppression. The rapid decay of SLE, but not WEE, antibody may allow the relapse of chronic infections of SLE, but not WEE, to produce viremias sufficiently elevated to infect mosquitoes.
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Affiliation(s)
- W K Reisen
- Arbovirus Research Unit, Center for Vector-borne Disease Research, School of Veterinary Medicine, University of California, Davis 95616, USA
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Lothrop HD, Reisen WK. Landscape affects the host-seeking patterns of Culex tarsalis (Diptera: Culicidae) in the Coachella Valley of California. JOURNAL OF MEDICAL ENTOMOLOGY 2001; 38:325-332. [PMID: 11296843 DOI: 10.1603/0022-2585-38.2.325] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Effective arbovirus transmission requires that the principal vertebrate hosts and vectors have frequent contact. Vegetation and other landscape features used by roosting or nesting birds at night dictate their exposure to nocturnally active host-seeking Culex tarsalis Coquillett and therefore to western equine encephalomyelitis and St. Louis encephalitis viruses. Precipitin tests on 645 Cx. tarsalis that were collected resting and host-seeking near the Salton Sea in Coachella Valley, CA, indicated that passeriform birds (64%) and rabbits (25%) were the most frequent bloodmeal hosts and that the percentage of females feeding on birds varied temporally as an inverse fuction of mosquito abundance. Blood meals were not taken from communally roosting water birds. The spatial distribution of host-seeking females then was investigated by deploying dry ice baited traps within seven sites representative of habitats found along the Salton Sea. Mosquito catch was greatest at traps within elevated vegetation such as Tamarisk, mesquite, cattails, and orchards and lowest at traps positioned at snags over water, sand bars, open fields, and within housing in a small rural community. These data indicate that host-seeking Cx. tarsalis females congregated at specific landscape features that were not necessarily associated with large concentrations of potential bloodmeal hosts.
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Affiliation(s)
- H D Lothrop
- Arbovirus Research Unit, Center for Vector-Borne Disease Research, School of Veterinary Medicine, University of California, Davis, USA
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Komar N, Panella NA, Boyce E. Exposure of domestic mammals to West Nile virus during an outbreak of human encephalitis, New York City, 1999. Emerg Infect Dis 2001; 7:736-8. [PMID: 11585540 PMCID: PMC2631764 DOI: 10.3201/eid0704.010424] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We evaluated West Nile (WN) virus seroprevalence in healthy horses, dogs, and cats in New York City after an outbreak of human WN virus encephalitis in 1999. Two (3%) of 73 horses, 10 (5%) of 189 dogs, and none of 12 cats tested positive for WN virus-neutralizing antibodies. Domestic mammals should be evaluated as sentinels for local WN virus activity and predictors of the infection in humans.
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Affiliation(s)
- N Komar
- Centers for Disease Control and Prevention, P.O. Box 2087, Fort Collins, CO 80522, USA.
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