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Shocket MS, Verwillow AB, Numazu MG, Slamani H, Cohen JM, El Moustaid F, Rohr J, Johnson LR, Mordecai EA. Transmission of West Nile and five other temperate mosquito-borne viruses peaks at temperatures between 23°C and 26°C. eLife 2020; 9:e58511. [PMID: 32930091 PMCID: PMC7492091 DOI: 10.7554/elife.58511] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 08/18/2020] [Indexed: 12/22/2022] Open
Abstract
The temperature-dependence of many important mosquito-borne diseases has never been quantified. These relationships are critical for understanding current distributions and predicting future shifts from climate change. We used trait-based models to characterize temperature-dependent transmission of 10 vector-pathogen pairs of mosquitoes (Culex pipiens, Cx. quinquefascsiatus, Cx. tarsalis, and others) and viruses (West Nile, Eastern and Western Equine Encephalitis, St. Louis Encephalitis, Sindbis, and Rift Valley Fever viruses), most with substantial transmission in temperate regions. Transmission is optimized at intermediate temperatures (23-26°C) and often has wider thermal breadths (due to cooler lower thermal limits) compared to pathogens with predominately tropical distributions (in previous studies). The incidence of human West Nile virus cases across US counties responded unimodally to average summer temperature and peaked at 24°C, matching model-predicted optima (24-25°C). Climate warming will likely shift transmission of these diseases, increasing it in cooler locations while decreasing it in warmer locations.
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Affiliation(s)
- Marta S Shocket
- Department of Biology, Stanford UniversityStanfordUnited States
- Department of Ecology and Evolutionary Biology, University of California Los AngelesLos AngelesUnited States
| | | | - Mailo G Numazu
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Hani Slamani
- Department of Statistics, Virginia Polytechnic Institute and State University (Virginia Tech)BlacksburgUnited States
| | - Jeremy M Cohen
- Department of Integrative Biology, University of South FloridaTampaUnited States
- Department of Forest and Wildlife Ecology, University of WisconsinMadisonUnited States
| | - Fadoua El Moustaid
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech)BlacksburgUnited States
| | - Jason Rohr
- Department of Integrative Biology, University of South FloridaTampaUnited States
- Department of Biological Sciences, Eck Institute of Global Health, Environmental Change Initiative, University of Notre DameSouth BendUnited States
| | - Leah R Johnson
- Department of Statistics, Virginia Polytechnic Institute and State University (Virginia Tech)BlacksburgUnited States
- Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech)BlacksburgUnited States
| | - Erin A Mordecai
- Department of Biology, Stanford UniversityStanfordUnited States
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Introduction and Dispersal of Sindbis Virus from Central Africa to Europe. J Virol 2019; 93:JVI.00620-19. [PMID: 31142666 PMCID: PMC6675900 DOI: 10.1128/jvi.00620-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 05/15/2019] [Indexed: 11/20/2022] Open
Abstract
This study shows that only a single introduction of SINV into a new geographical area is required for spread and establishment, provided that the requisite vector(s) and reservoir(s) of epizootological and epidemiological importance are present. Furthermore, we present the first report of recombination between two strains of SINV in nature. Our study increases the knowledge on new introductions and dispersal of arboviruses in general and of SINV in particular. Bird-hosted viruses have the potential to be transported over large areas of the world and to be transmitted in distant geographical regions. Sindbis virus (SINV) is a mosquito-borne alphavirus that is locally amplified in a bird-mosquito enzootic cycle and distributed all over the Old World and Australia/Oceania. Sindbis virus genotype I (SINV-I) is the cause of disease outbreaks in humans in South Africa as well as in northern Europe. To trace the evolutionary history and potential strain-disease association of SINV-I, we sequenced 36 complete genomes isolated from field material in Europe, as well as in Africa and the Middle East, collected over 58 years. These were analyzed together with 30 additional published whole SINV-I genomes using Bayesian analysis. Our results suggested that SINV-I was introduced only once to northern Europe from central Africa, in the 1920s. After its first introduction to Sweden, it spread east and southward on two separate occasions in the 1960s and 1970s. Another introduction from central Africa to southern/central Europe seems to have occurred, and where these two introductions meet, one recombination event was detected in central Europe. In addition, another recombinant strain was found in central Africa, where the most divergent SINV-I strains also originated. IMPORTANCE This study shows that only a single introduction of SINV into a new geographical area is required for spread and establishment, provided that the requisite vector(s) and reservoir(s) of epizootological and epidemiological importance are present. Furthermore, we present the first report of recombination between two strains of SINV in nature. Our study increases the knowledge on new introductions and dispersal of arboviruses in general and of SINV in particular.
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Zittra C, Moog O, Christian E, Fuehrer HP. DNA-aided identification of Culex mosquitoes (Diptera: Culicidae) reveals unexpected diversity in underground cavities in Austria. Parasitol Res 2019; 118:1385-1391. [PMID: 30919062 PMCID: PMC6478630 DOI: 10.1007/s00436-019-06277-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 02/26/2019] [Indexed: 01/08/2023]
Abstract
Subterranean cavities serve as resting places and hibernation shelters for mosquitoes. In Europe, members of the genus Culex are often the most abundant insects on cave walls. Culex pipiens L., the common house mosquito, exists in two physically very similar, yet genetically and ecologically distinct biotypes (or forms, 'f.'), namely Cx. pipiens f. pipiens and Cx. pipiens f. molestus. Autogeny and stenogamy of the latter form have been interpreted as adaptations to underground habitats. The epigean occurrence of the two biotypes and their hybrids was recently examined in Eastern Austria, but the hypogean distribution of the Cx. pipiens complex and morphologically similar non-members such as Cx. torrentium is unknown. Considering the key role of Culex mosquitoes in the epidemiology of certain zoonotic pathogens, the general paucity of data on species composition and relative abundance in subterranean shelters appears unfortunate.For a first pertinent investigation in Austria, we collected mosquitoes in four eastern federal states. Based on analyses of the ACE2 gene and the CQ11 microsatellite locus, 150 female and three male mosquitoes of the genus Culex, two females of the genus Culiseta and a single female of the genus Anopheles were determined to species level or below. In our catches, Cx. pipiens f. pipiens exceeded the apparent abundance of the purportedly cave-adapted Cx. pipiens f. molestus many times over. Records of Cx. hortensis and Cx. territans, two species rarely collected in Austria, lead us to infer that underground habitats host a higher diversity of culicine mosquitoes than previously thought.
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Affiliation(s)
- Carina Zittra
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria.
| | - Otto Moog
- Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Gregor-Mendel-Straße 33/DG, 1180, Vienna, Austria
| | - Erhard Christian
- Institute of Zoology, University of Natural Resources and Life Sciences, Gregor-Mendel-Straße 33, 1180, Vienna, Austria
| | - Hans-Peter Fuehrer
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
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Lwande OW, Näslund J, Lundmark E, Ahlm K, Ahlm C, Bucht G, Evander M. Experimental Infection and Transmission Competence of Sindbis Virus in Culex torrentium and Culex pipiens Mosquitoes from Northern Sweden. Vector Borne Zoonotic Dis 2018; 19:128-133. [PMID: 30300110 PMCID: PMC6354595 DOI: 10.1089/vbz.2018.2311] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Sindbis virus (SINV) is a mosquito-borne Alphavirus known to infect birds and cause intermittent outbreaks among humans in Fenno-Scandia. In Sweden, the endemic area has mainly been in central Sweden. Recently, SINV infections have emerged to northern Sweden, but the vectorial efficiency for SINV of mosquito species in this northern region has not yet been ascertained. OBJECTIVE Mosquito larvae were sampled from the Umeå region in northern Sweden and propagated in a laboratory to adult stage to investigate the infection, dissemination, and transmission efficiency of SINV in mosquitoes. MATERIALS AND METHODS The mosquito species were identified by DNA barcoding of the cytochrome oxidase I gene. Culex torrentium was the most abundant (82.2%) followed by Culex pipiens (14.4%), Aedes annulipes (1.1%), Anopheles claviger (1.1%), Culiseta bergrothi (1.1%), or other unidentified species (1.1%). Mosquitoes were fed with SINV-infected blood and monitored for 29 days to determine the viral extrinsic incubation period. Infection and dissemination were determined by RT-qPCR screening of dissected body parts of individual mosquitoes. Viral transmission was determined from saliva collected from individual mosquitoes at 7, 14, and 29 days. SINV was detected by cell culture using BHK-21 cells, RT-qPCR, and sequencing. RESULTS Cx. torrentium was the only mosquito species in our study that was able to transmit SINV. The overall transmission efficiency of SINV in Cx. torrentium was 6.8%. The rates of SINV infection, dissemination, and transmission in Cx. torrentium were 11%, 75%, and 83%, respectively. CONCLUSIONS Cx. torrentium may be the key vector involved in SINV transmission in northern Sweden.
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Affiliation(s)
- Olivia Wesula Lwande
- 1 Virology, Department of Clinical Microbiology, Umeå University , Umeå, Sweden .,2 Arctic Research Centre at Umeå University , Umeå, Sweden
| | - Jonas Näslund
- 3 Swedish Defence Research Agency , CBRN Defence and Security, Umeå, Sweden
| | - Eva Lundmark
- 3 Swedish Defence Research Agency , CBRN Defence and Security, Umeå, Sweden
| | - Kristoffer Ahlm
- 4 Infection and Immunology, Department of Clinical Microbiology, Umeå University , Umeå, Sweden
| | - Clas Ahlm
- 2 Arctic Research Centre at Umeå University , Umeå, Sweden .,4 Infection and Immunology, Department of Clinical Microbiology, Umeå University , Umeå, Sweden
| | - Göran Bucht
- 3 Swedish Defence Research Agency , CBRN Defence and Security, Umeå, Sweden
| | - Magnus Evander
- 1 Virology, Department of Clinical Microbiology, Umeå University , Umeå, Sweden .,2 Arctic Research Centre at Umeå University , Umeå, Sweden
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Leggewie M, Krumkamp R, Badusche M, Heitmann A, Jansen S, Schmidt-Chanasit J, Tannich E, Becker SC. Culex torrentium mosquitoes from Germany are negative for Wolbachia. MEDICAL AND VETERINARY ENTOMOLOGY 2018; 32:115-120. [PMID: 28906572 DOI: 10.1111/mve.12270] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/20/2017] [Accepted: 07/29/2017] [Indexed: 06/07/2023]
Abstract
Wolbachia (Rickettsiales: Anaplasmataceae) infects a wide range of arthropods, including several mosquito species. The bacterium is known to induce a plethora of phenotypes in its host, examples being the reproductive phenotype cytoplasmic incompatibility or resistance against infection with arboviruses. The latter is especially relevant when assessing the vector competence of mosquito species for emerging arboviruses. Thus, knowledge of Wolbachia infection status is important for the assessment of vector competence. To facilitate Wolbachia screening in mosquito populations, a quantitative polymerase chain reaction (qPCR) assay was developed to enable high-throughput analysis of mosquito samples. Using this assay, the Wolbachia infection status of the two most common Culex mosquito species in Germany, Culex pipiens biotype pipiens Linnaeus (Diptera: Culicidae) and Culex torrentium Martini (Diptera: Culicidae), was assessed. About 93% of all tested C. pipiens biotype pipiens individuals were positive for Wolbachia, whereas none of the C. torrentium samples was found to be infected. Furthermore, other applications of the qPCR assay were explored by assessing a potential link between the levels of Wolbachia and West Nile virus (WNV) infections in German C. pipiens biotype pipiens mosquitoes. No relationship was found between the two variables, indicating that a Wolbachia-induced antiviral phenotype in this mosquito population is not exclusively attributable to the general level of bacterial infection.
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Affiliation(s)
- M Leggewie
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - R Krumkamp
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
| | - M Badusche
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - A Heitmann
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - S Jansen
- Arbovirology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - J Schmidt-Chanasit
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
- Arbovirology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - E Tannich
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - S C Becker
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany
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The Role of Culex pipiens L. (Diptera: Culicidae) in Virus Transmission in Europe. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15020389. [PMID: 29473903 PMCID: PMC5858458 DOI: 10.3390/ijerph15020389] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 11/17/2022]
Abstract
Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the Culex pipiens species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different Cx. pipiens ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of Cx. pipiens in Europe, and how this influences arbovirus transmission.
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Leggewie M, Badusche M, Rudolf M, Jansen S, Börstler J, Krumkamp R, Huber K, Krüger A, Schmidt-Chanasit J, Tannich E, Becker SC. Culex pipiens and Culex torrentium populations from Central Europe are susceptible to West Nile virus infection. One Health 2016; 2:88-94. [PMID: 28616480 PMCID: PMC5462652 DOI: 10.1016/j.onehlt.2016.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 04/14/2016] [Accepted: 04/19/2016] [Indexed: 11/18/2022] Open
Abstract
West Nile virus (WNV), a Flavivirus with an avian primary host, is already widespread in Europe and might also pose an infection risk to Germany, should competent mosquito vectors be present. Therefore, we analysed the ability of WNV to infect German Culex mosquitoes with special emphasis on field collected specimens of Culex torrentium and Culex pipiens biotype pipiens. We collected egg rafts of Culex mosquitoes over two subsequent seasons at two geographically distinct sampling areas in Germany and differentiated the samples by molecular methods. Adult females, reared from the various egg rafts, were challenged with WNV by feeding of artificial blood meals. WNV infection was confirmed by real-time RT-PCR and virus titration. The results showed that field collected C. pipiens biotype pipiens and C. torrentium mosquitoes native to Germany are susceptible to WNV infection at 25 °C as well as 18 °C incubation temperature. C. torrentium mosquitoes, which have not been established as WNV vector so far, were the most permissive species tested with maximum infection rates of 96% at 25 °C. Furthermore, a disseminating infection was found in up to 94% of tested C. pipiens biotype pipiens and 100% of C. torrentium. Considering geographical variation of susceptibility, C. pipiens biotype pipiens mosquitoes from Southern Germany were more susceptible to WNV infection than corresponding populations from Northern Germany. All in all, we observed high infection and dissemination rates even at a low average ambient temperature of 18 °C. The high susceptibility of German Culex populations for WNV indicates that an enzootic transmission cycle in Germany could be possible.
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Affiliation(s)
- Mayke Leggewie
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Marlis Badusche
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Martin Rudolf
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Stephanie Jansen
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Jessica Börstler
- Arbovirology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Ralf Krumkamp
- Research Group Infectious Disease Epidemiology, Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
| | - Katrin Huber
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
- KABS e.V., Ludwigstrasse 99, 67165 Waldsee, Germany
| | - Andreas Krüger
- Bundeswehr Hospital Hamburg, Department Tropical Medicine, Entomology Group, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Jonas Schmidt-Chanasit
- Arbovirology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
| | - Egbert Tannich
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel, Hamburg, Germany
- Department of Parasitology, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Stefanie C. Becker
- Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
- Institute for Parasitology, University of Veterinary Medicine Hannover, 30599 Hannover, Germany
- Corresponding author.
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Zittra C, Flechl E, Kothmayer M, Vitecek S, Rossiter H, Zechmeister T, Fuehrer HP. Ecological characterization and molecular differentiation of Culex pipiens complex taxa and Culex torrentium in eastern Austria. Parasit Vectors 2016; 9:197. [PMID: 27067139 PMCID: PMC4828795 DOI: 10.1186/s13071-016-1495-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/05/2016] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Culex pipiens complex taxa differ in behaviour, ecophysiology and epidemiologic importance. Despite their epidemiologic significance, information on genetic diversity, occurrence and seasonal and spatial distribution patterns of the Cx. pipiens complex is still insufficient. Assessment of seasonal and spatial distribution patterns of Culex pipiens forms and their congener Cx. torrentium is crucial for the understanding of their vector-pathogen dynamics. METHODS Female mosquitoes were trapped from April-October 2014 twice a month for a 24-h time period with BG-sentinel traps at 24 sampling sites in eastern Austria, using carbon dioxide as attractant. Ecological forms of Cx. pipiens s.l. and their hybrids were differentiated using the CQ11 locus, and Cx. pipiens forms and their congener Cx. torrentium using the ACE-2 gene. Differential exploitation of ecological niches by Cx. pipiens forms and Cx. torrentium was analysed using likelihood ratio tests. Possible effects of environmental parameters on these taxa were tested using PERMANOVA based on distance matrices and, if significant, were modelled in nMDS ordination space to estimate non-linear relationships. RESULTS For this study, 1476 Culex spp. were sampled. Culex pipiens f. pipiens representing 87.33 % of the total catch was most abundant, followed by hybrids of both forms (5.62 %), Cx. torrentium (3.79 %) and Cx. pipiens f. molestus (3.25 %). Differences in proportional abundances were found between land cover classes. Ecological parameters affecting seasonal and spatial distribution of these taxa in eastern Austria are precipitation duration, air temperature, sunlight and the interaction term of precipitation amount and the Danube water level, which can be interpreted as a proxy for breeding habitat availability. CONCLUSIONS The Cx. pipiens complex of eastern Austria comprises both ecologically different forms, the mainly ornithophilic form pipiens and the mainly mammalophilic and anthropophilic form molestus. Heterogeneous agricultural areas as areas of coexistence may serve as hybridization zones, resulting in potential bridge vectors between birds and humans. Occurrence, seasonal and spatial distribution patterns of the Cx. pipiens complex and Cx. torrentium and the presence of hybrids between both forms were quantified for the first time in Austria. These findings will improve the knowledge of their vector-pathogen dynamics in this country.
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Affiliation(s)
- Carina Zittra
- Department of Pathobiology, Institute of Parasitology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Eva Flechl
- Department of Pathobiology, Institute of Parasitology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Michael Kothmayer
- Department of Pathobiology, Institute of Parasitology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Simon Vitecek
- Department of Limnology and Bio-Oceanography, University of Vienna, Vienna, Austria
| | | | | | - Hans-Peter Fuehrer
- Department of Pathobiology, Institute of Parasitology, University of Veterinary Medicine Vienna, Vienna, Austria.
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Adouchief S, Smura T, Sane J, Vapalahti O, Kurkela S. Sindbis virus as a human pathogen-epidemiology, clinical picture and pathogenesis. Rev Med Virol 2016; 26:221-41. [DOI: 10.1002/rmv.1876] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/02/2016] [Accepted: 02/04/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Samuel Adouchief
- Department of Virology, Faculty of Medicine; University of Helsinki; Helsinki Finland
| | - Teemu Smura
- Department of Virology, Faculty of Medicine; University of Helsinki; Helsinki Finland
| | - Jussi Sane
- National institute for Health and Welfare (THL); Helsinki Finland
| | - Olli Vapalahti
- Department of Virology, Faculty of Medicine; University of Helsinki; Helsinki Finland
- Department of Virology and Immunology, HUSLAB; Helsinki University Central Hospital; Helsinki Finland
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine; University of Helsinki; Helsinki Finland
| | - Satu Kurkela
- Department of Virology, Faculty of Medicine; University of Helsinki; Helsinki Finland
- Department of Virology and Immunology, HUSLAB; Helsinki University Central Hospital; Helsinki Finland
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Hesson JC, Verner-Carlsson J, Larsson A, Ahmed R, Lundkvist Å, Lundström JO. Culex torrentium Mosquito Role as Major Enzootic Vector Defined by Rate of Sindbis Virus Infection, Sweden, 2009. Emerg Infect Dis 2016; 21:875-8. [PMID: 25898013 PMCID: PMC4412225 DOI: 10.3201/eid2105.141577] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We isolated Sindbis virus (SINV) from the enzootic mosquito vectors Culex torrentium, Cx. pipiens, and Culiseta morsitans collected in an area of Sweden where SINV disease is endemic. The infection rate in Cx. torrentium mosquitoes was exceptionally high (36 infections/1,000 mosquitoes), defining Cx. torrentium as the main enzootic vector of SINV in Scandinavia.
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Lühken R, Steinke S, Leggewie M, Tannich E, Krüger A, Becker S, Kiel E. Physico-Chemical Characteristics of Culex pipiens sensu lato and Culex torrentium (Diptera: Culicidae) Breeding Sites in Germany. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:932-936. [PMID: 26336210 DOI: 10.1093/jme/tjv070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 05/19/2015] [Indexed: 06/05/2023]
Abstract
Culex pipiens sensu lato (L.) and Culex torrentium Martini, 1925 are two widely distributed mosquito species in Europe. Due to difficulties in morphological discrimination, the current knowledge on differences in the breeding ecology is fragmentary. Therefore, this study evaluated the relation between the presence-absence of both species at various types of breeding habitats in response to physico-chemical parameters, using a recently developed molecular assay that allows reliable species-specific typing of larvae and pupae. The results revealed that the two species often occur in sympatry at the studied breeding sites, and there were no substantial differences concerning presence-absence of the two species with regard to the various environmental parameters investigated.
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Affiliation(s)
- Renke Lühken
- Research group Aquatic Ecology and Nature Conservation, Carl von Ossietzky University, Ammerländer Heerstraße 114-118, 26129 Oldenburg, Germany. Corresponding author, e-mail:
| | - Sonja Steinke
- Research group Aquatic Ecology and Nature Conservation, Carl von Ossietzky University, Ammerländer Heerstraße 114-118, 26129 Oldenburg, Germany
| | - Mayke Leggewie
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Egbert Tannich
- Corresponding author, e-mail: . German Centre for Infection Research, partner site Hamburg-Luebeck-Borstel, HamburgBernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Andreas Krüger
- Bundeswehr Hospital Hamburg, Lesserstraße 180, 22049 Hamburg, Germany. Okavango Research Institute, Maun, 4775 Notwane Rd. Gaborone, Botswana
| | - Stefanie Becker
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany. Institute for Infectiology, Friedrich-Loeffler-Institute, Am Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | - Ellen Kiel
- Research group Aquatic Ecology and Nature Conservation, Carl von Ossietzky University, Ammerländer Heerstraße 114-118, 26129 Oldenburg, Germany
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Hesson JC, Ignell R, Hill SR, Östman Ö, Lundström JO. Trapping biases of Culex torrentium and Culex pipiens revealed by comparison of captures in CDC traps, ovitraps, and gravid traps. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2015; 40:158-163. [PMID: 26047196 DOI: 10.1111/jvec.12145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/22/2014] [Indexed: 06/04/2023]
Abstract
We evaluate three trapping methods for their effectiveness at capturing Culex pipiens and Culex torrentium, both enzootic vectors of bird-associated viruses in Europe. The comparisons, performed in two regions in Sweden, were among CDC traps baited with carbon dioxide, gravid traps, and ovitraps baited with hay infusion. The proportions of the two Culex species in a catch differed between trap types, with CDC traps catching a lower proportion of Cx. torrentium than both gravid traps and ovitraps. Between gravid traps and ovitraps, there was no difference in the proportions of the two species. The results indicate that Cx. torrentium may go undetected or underestimated compared to Cx. pipiens when using carbon dioxide baited CDC traps. The new insight of trap bias presented here adds an important dimension to consider when investigating these vectors of bird-associated viruses in the field.
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Affiliation(s)
- Jenny C Hesson
- Uppsala University, Department of Medical Biochemistry and Microbiology (IMBIM), Zoonosis Science Center, Uppsala, Sweden.
- Uppsala University, Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala, Sweden.
| | - Rickard Ignell
- Swedish University of Agricultural Sciences, Unit of Chemical Ecology, Department of Plant Protection Biology, Alnarp, Sweden
| | - Sharon R Hill
- Swedish University of Agricultural Sciences, Unit of Chemical Ecology, Department of Plant Protection Biology, Alnarp, Sweden
| | - Örjan Östman
- Uppsala University, Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala, Sweden
| | - Jan O Lundström
- Uppsala University, Department of Medical Biochemistry and Microbiology (IMBIM), Zoonosis Science Center, Uppsala, Sweden
- Uppsala University, Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala, Sweden
- Swedish Biological Mosquito Control Project, Nedre Dalälvens Utvecklings AB, Gysinge, Sweden
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Hesson JC, Rettich F, Merdić E, Vignjević G, Ostman O, Schäfer M, Schaffner F, Foussadier R, Besnard G, Medlock J, Scholte EJ, Lundström JO. The arbovirus vector Culex torrentium is more prevalent than Culex pipiens in northern and central Europe. MEDICAL AND VETERINARY ENTOMOLOGY 2014; 28:179-186. [PMID: 23947434 DOI: 10.1111/mve.12024] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 06/11/2013] [Accepted: 06/24/2013] [Indexed: 06/02/2023]
Abstract
Two species of arbovirus vector, Culex torrentium and Culex pipiens (Diptera: Culicidae), occur in several European countries, but difficulties in their accurate identification and discrimination have hampered both detailed and large-scale distribution and abundance studies. Using a molecular identification method, we identified to species 2559 larvae of Cx. pipiens/torrentium collected from 138 sites in 13 European countries ranging from Scandinavia to the Mediterranean coast. In addition, samples of 1712 males of Cx. pipiens/torrentium collected at several sites in the Czech Republic were identified to species based on the morphology of their hypopygia. We found that the two species occur together in large areas of Europe, and that Cx. torrentium dominates in northern Europe and Cx. pipiens dominates south of the Alps. The transition in dominance occurs in central Europe, where both species are roughly equally common. There was a strong correlation between the length of the growing season at different sites and occurrences of the two species. As the growing season increases, the proportion and detection of Cx. torrentium decrease, whereas those of Cx. pipiens increase. The present findings have important consequences for the interpretation of the results of studies on major enzootic and link-vectors of mosquito-borne bird-associated viruses (i.e. Sindbis, West Nile and Usutu viruses), especially in central Europe and Scandinavia.
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Affiliation(s)
- J C Hesson
- Population Conservation Biology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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14
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Werblow A, Bolius S, Dorresteijn AWC, Melaun C, Klimpel S. Diversity of Culex torrentium Martini, 1925 - a potential vector of arboviruses and filaria in Europe. Parasitol Res 2013; 112:2495-501. [PMID: 23604567 DOI: 10.1007/s00436-013-3418-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 03/27/2013] [Indexed: 10/26/2022]
Abstract
Culex torrentium is one of the most common mosquito species in Germany. Due to its sympatric occurrence as well as its similar morphological and ecological characteristics, it has often been confused with another common species, Culex pipiens. Both species are known to be potential vectors for different arboviruses (not only in Germany) with C. torrentium being a possible vector for Sindbis or Ockelbo virus. In our study, we analyzed the genetic variability in a 658 bp fragment of the cytochrome c oxidase subunit I gene (coxI) of C. torrentium, from nine localities in the Frankfurt/Rhine-Main Metropolitan Region. The results of our genetic survey indicate a higher genetic diversity in this gene region for C. torrentium than for the morphologically similar C. pipiens. Our findings may explain the difficulties in the past to find morphological characteristics that apply to all populations of C. torrentium, when attempting to separate them clearly from C. pipiens, by any other criteria than male genitalia. Being ornithophilic, possible hybrids between C. torrentium and the humanophilic C. pipiens biotype molestus, could potentially serve as important vectors for zoonotic diseases. Therefore, we recommend that greater emphasis is placed on the ecological characteristics, population structure, and the taxonomy of this often neglected species, in the future.
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Affiliation(s)
- Antje Werblow
- Biodiversity and Climate Research Centre (BiK-F), Medical Biodiversity and Parasitology; Goethe-University, Institute for Ecology, Evolution and Diversity; Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, Frankfurt am Main 60325, Germany
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15
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Carrington LB, Seifert SN, Armijos MV, Lambrechts L, Scott TW. Reduction of Aedes aegypti vector competence for dengue virus under large temperature fluctuations. Am J Trop Med Hyg 2013; 88:689-97. [PMID: 23438766 DOI: 10.4269/ajtmh.12-0488] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Diurnal temperature fluctuations can fundamentally alter mosquito biology and mosquito-virus interactions in ways that impact pathogen transmission. We investigated the effect of two daily fluctuating temperature profiles on Aedes aegypti vector competence for dengue virus (DENV) serotype-1. A large diurnal temperature range of 18.6°C around a 26°C mean, corresponding with the low DENV transmission season in northwestern Thailand, reduced midgut infection rates and tended to extend the virus extrinsic incubation period. Dissemination was first observed at day 7 under small fluctuations (7.6°C; corresponding with high DENV transmission) and constant control temperature, but not until Day 11 for the large diurnal temperature range. Results indicate that female Ae. aegypti in northwest Thailand are less likely to transmit DENV during the low than high transmission season because of reduced DENV susceptibility and extended virus extrinsic incubation period. Better understanding of DENV transmission dynamics will come with improved knowledge of temperature effects on mosquito-virus interactions.
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Danabalan R, Ponsonby DJ, Lintoni YM. A critical assessment of available molecular identification tools for determining the status of Culex pipiens s.l. in the United Kingdom. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2012; 28:68-74. [PMID: 23401945 DOI: 10.2987/8756-971x-28.0.68] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Until the relatively recent application of molecular identification tools, identification of Culex pipiens f. pipiens and Cx. pipiens f. molestus relied on expressed ecological characteristics, including autogeny, host preference and stenogamy. Herein we test two DNA assays, one based on the microsatellite locus CQ11 and the other on species-diagnostic nucleotide bases in the mtDNA cytochrome oxidase I, on 322 wild-caught Cx. pipiens s.l. collected in above ground habitats from 6 counties across southern England and Wales. Of the 322 Culex pipiens s.l. screened using the CQ11 assay, 205 were identified as Cx. pipiens f. pipiens, 95 as Cx. pipiens f. molestus and 22 were determined as hybrids. Neither above ground Cx. pipiens f. molestus, nor hybrids have previously been reported in UK. However, comparison of COI barcodes (658bp) from 30 individuals from the above defined grouping indicated that inadvertent inclusion of specimens of Cx. torrentium resulted in the expected product sizes purportedly diagnostic for Cx. pipiens f. molestus, Cx. pipiens f. pipiens and hybrids in the CQ11 assay. COI sequences showed Cx. torrentium was misidentified as Cx. pipiens s.l. in more than 50% of cases and that all above ground Cx. pipiens s.l. collected in this study were in fact Cx. pipiens f. pipiens. Thus in regions of the Palearctic where Cx. torrentium and Cx. pipiens s.l. are sympatric, we showed that the CQ11 assay produces misleading results and should not be used.
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Turell MJ. Members of the Culex pipiens complex as vectors of viruses. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2012; 28:123-126. [PMID: 23401952 DOI: 10.2987/8756-971x-28.4.123] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Members of the Culex pipiens complex have been implicated as vectors of a number of arboviruses including St. Louis encephalitis, West Nile, Sindbis, and Rift Valley fever viruses. For some viruses, such as West Nile virus, laboratory studies have indicated that various members of this complex have a similar ability to become infected with and transmit virus, thus providing evidence for the similarity among the various members of this complex. On the other hand, although strains of Cx. pipiens from various parts of the world have all been relatively efficient vectors of Rift Valley fever virus, Cx. quinquefasciatus from Africa, Australia, and North America have been nearly refractory to this virus, thus indicating that the various members of this complex do not necessarily respond similarly to a particular arbovirus. Based on the similar response to some viruses and differing response to others, Cx. pipiens and Cx. quinquefasciatus appear to be closely related, but distinct species.
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Affiliation(s)
- Michael J Turell
- Department of Vector Assessment, Virology Division, USAMRIID, 1425 Porter Street, Fort Detrick, Maryland 21702-5011, USA
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18
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Hesson JC, Östman Ö, Schäfer M, Lundström JO. Geographic Distribution and Relative Abundance of the Sibling Vector Species Culex torrentium and Culex pipiens in Sweden. Vector Borne Zoonotic Dis 2011; 11:1383-9. [DOI: 10.1089/vbz.2011.0630] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jenny C. Hesson
- Department of Ecology and Genetics, Population and Conservation Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Örjan Östman
- Department of Ecology and Genetics, Population and Conservation Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Martina Schäfer
- Department of Ecology and Genetics, Population and Conservation Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Swedish Biological Mosquito Control Project, Nedre Dalälvens Utvecklings AB, Gysinge, Sweden
| | - Jan O. Lundström
- Department of Ecology and Genetics, Population and Conservation Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Swedish Biological Mosquito Control Project, Nedre Dalälvens Utvecklings AB, Gysinge, Sweden
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Hesson JC, Lundström JO, Halvarsson P, Erixon P, Collado A. A sensitive and reliable restriction enzyme assay to distinguish between the mosquitoes Culex torrentium and Culex pipiens. MEDICAL AND VETERINARY ENTOMOLOGY 2010; 24:142-149. [PMID: 20444079 DOI: 10.1111/j.1365-2915.2010.00871.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Culex pipiens pipiens Linnaeus and Culex torrentium Martini (Diptera: Culicidae) are closely related vector species that exist sympatrically in Europe. The two species are morphologically almost identical and can only be distinguished with certainty by characters of the male genitalia. Hence, correct species identification and conclusions on distribution and vector status are very difficult and often neglected. Therefore, we developed a reliable and simple mitochondrial cytochrome c oxidase subunit I (COI) gene restriction enzyme assay to discriminate between Cx. pipiens and Cx. torrentium, based on the analysis of morphologically identified male specimens. We sequenced approximately 830 bp in the 3' region of the mitochondrial COI gene of 18 morphologically identified males of Cx. pipiens and Cx. torrentium. Two restriction enzymes (FspBI and SspI) that could distinguish between the two species according to species-specific differences in these sequences were chosen. The restriction enzymes were tested on 227 samples from Sweden and verified by sequencing 44 of them. The enzyme FspBI correctly identified all investigated samples; the enzyme SspI identified all samples except one Cx. torrentium. We hope the method and the findings presented here will help to shed light on the true distribution and relative proportions of the two species in Europe.
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Affiliation(s)
- J C Hesson
- Department of Ecology and Evolution/Population Biology, Evolutionary Biology Centre, Uppsala University, SE 752 36 Uppsala, Sweden.
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20
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Hubálek Z. Mosquito-borne viruses in Europe. Parasitol Res 2008; 103 Suppl 1:S29-43. [PMID: 19030884 DOI: 10.1007/s00436-008-1064-7] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 05/26/2008] [Indexed: 11/25/2022]
Abstract
The number of mosquito-borne viruses ('moboviruses') occurring in Europe since the twentieth century now stands at ten; they belong to three families-Togaviridae (Sindbis, Chikungunya), Flaviviridae (West Nile, Usutu, Dengue), and Bunyaviridae (Batai, Tahyna, Snowshoe hare, Inkoo, Lednice). Several of them play a definite role in human or animal pathology (Sindbis, Chikungunya, Dengue, West Nile, Tahyna). Mobovirus outbreaks are strictly determined by the presence and/or import of particular competent vectors of the disease. Ecological variables affect moboviruses considerably; the main factors are population density of mosquito vectors and their vertebrate hosts, intense summer precipitations or floods, summer temperatures and drought, and presence of appropriate habitats, e.g., wetlands, small water pools, or intravillan sewage systems. A surveillance for moboviruses and the diseases they cause in Europe is recommendable, because the cases may often pass unnoticed or misdiagnosed not only in free-living vertebrates but also in domestic animals and even in humans.
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Affiliation(s)
- Zdenek Hubálek
- Institute of Vertebrate Biology, Academy of Sciences, Kvetná 8, 60365, Brno, Czech Republic.
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21
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Kilpatrick AM, Meola MA, Moudy RM, Kramer LD. Temperature, viral genetics, and the transmission of West Nile virus by Culex pipiens mosquitoes. PLoS Pathog 2008; 4:e1000092. [PMID: 18584026 PMCID: PMC2430533 DOI: 10.1371/journal.ppat.1000092] [Citation(s) in RCA: 283] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Accepted: 05/20/2008] [Indexed: 12/11/2022] Open
Abstract
The distribution and intensity of transmission of vector-borne pathogens can be strongly influenced by the competence of vectors. Vector competence, in turn, can be influenced by temperature and viral genetics. West Nile virus (WNV) was introduced into the United States of America in 1999 and subsequently spread throughout much of the Americas. Previously, we have shown that a novel genotype of WNV, WN02, first detected in 2001, spread across the US and was more efficient than the introduced genotype, NY99, at infecting, disseminating, and being transmitted by Culex mosquitoes. In the current study, we determined the relationship between temperature and time since feeding on the probability of transmitting each genotype of WNV. We found that the advantage of the WN02 genotype increases with the product of time and temperature. Thus, warmer temperatures would have facilitated the invasion of the WN02 genotype. In addition, we found that transmission of WNV accelerated sharply with increasing temperature, T, (best fit by a function of T(4)) showing that traditional degree-day models underestimate the impact of temperature on WNV transmission. This laboratory study suggests that both viral evolution and temperature help shape the distribution and intensity of transmission of WNV, and provides a model for predicting the impact of temperature and global warming on WNV transmission.
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Affiliation(s)
- A. Marm Kilpatrick
- Consortium for Conservation Medicine, New York, New York, United States of America
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, United States of America
| | - Mark A. Meola
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
| | - Robin M. Moudy
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
| | - Laura D. Kramer
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, New York, United States of America
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The Effect of Climate on the Incidence of Vector-Borne Viral Diseases in Australia: The Potential Value of Seasonal Forecasting. APPLICATIONS OF SEASONAL CLIMATE FORECASTING IN AGRICULTURAL AND NATURAL ECOSYSTEMS 2000. [DOI: 10.1007/978-94-015-9351-9_26] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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23
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Lord CC, Woolhouse ME, Heesterbeek JA, Mellor PS. Vector-borne diseases and the basic reproduction number: a case study of African horse sickness. MEDICAL AND VETERINARY ENTOMOLOGY 1996; 10:19-28. [PMID: 8834738 DOI: 10.1111/j.1365-2915.1996.tb00077.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The basic reproduction number, R0, can be used to determine factors important in the ability of a disease to invade or persist. We show how this number can be derived or estimated for vector-borne diseases with different complicating factors. African horse sickness is a viral disease transmitted mainly by the midge Culicoides imicola. We use this as an example of such a vector-transmitted disease where latent periods, seasonality in vector populations, and multiple host types may be important. The effect of vector population dynamics which are dependent on either host or vector density are also addressed. If density-dependent constraints on vector population density are less severe, R0 is more sensitive to vector mortality and the virus development rate. Host-dependent vector dynamics change the relationship between R0 and host population size. Seasonality can either increase or decrease the estimate of R0, depending on the lag between the peak of the midge population and the infective host population. The relative abundance of two host types is a factor in the ability of a disease to invade, but the strength of this factor depends on the differences between the hosts in recovery from infection, mortality and transmission. Removal of a reservoir host may increase R0.
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Affiliation(s)
- C C Lord
- Department of Zoology, University of Oxford, U.K
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24
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Niklasson B, Vene S. Vector-borne viral diseases in Sweden--a short review. ARCHIVES OF VIROLOGY. SUPPLEMENTUM 1996; 11:49-55. [PMID: 8800805 DOI: 10.1007/978-3-7091-7482-1_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ockelbo disease, caused by a Sindbis-related virus transmitted to man by mosquitoes, was first described in the central part of Sweden in the 1960s as clusters of patients with fever, arthralgia and rash. An average annual rate of 30 cases was recorded in the 1980s but no cases have been diagnosed during the last few years. Nephropathia epidemica (NE) characterized by fever, abdominal pain and renal dysfunction has been known to cause considerable morbidity in Sweden during the last 60 years but the etiologic agent (Puumala virus) was not isolated until 1983. This virus's main reservoir is the bank vole (Clethrionomys glareolus). NE is endemic in the northern two thirds of Sweden where more than a hundred cases are diagnosed each year. Tick-borne encephalitis transmitted by Ixodes ricinus ticks is restricted to the archipelago and Lake M-alaren on the east coast close to Stockholm. Between 30 and 110 cases are diagnosed every year. Inkoo virus, a California encephalitis group virus, has been isolated from mosquitoes in Sweden. The antibody prevalence to Inkoo virus is very high in a normal population, but no disease has as yet been associated with this virus in Sweden. Among the vector-borne virus diseases imported to Sweden, dengue is the most important, with approximately 50 cases recorded every year.
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Affiliation(s)
- B Niklasson
- Swedish Institute for Infectious Disease Control, Stockholm, Sweden
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25
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Mullens BA, Tabachnick WJ, Holbrook FR, Thompson LH. Effects of temperature on virogenesis of bluetongue virus serotype 11 in Culicoides variipennis sonorensis. MEDICAL AND VETERINARY ENTOMOLOGY 1995; 9:71-76. [PMID: 7696691 DOI: 10.1111/j.1365-2915.1995.tb00119.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Culicoides variipennis sonorensis females were fed bluetongue virus serotype 11 mixed in sheep blood and were held at constant temperatures of 32, 27, 21 and 15 degrees C. Virogenesis, as measured by enzyme-linked immunosorbent assay (ELISA), proceeded significantly faster at higher temperatures. Based on ELISA absorbance > or = 0.2, some flies first were categorized as infected after 1 day, 2 days and 4 days at 32, 27 and 21 degrees C, respectively. Peak levels of virus antigen were seen after 5-7, 7-13 and 18-22 days for flies held at 32, 27 and 21 degrees C, respectively. There was no significant virus replication in flies held at 15 degrees C for 22 days, but latent virus replicated and was detected easily (44% infection) 4-10 days after these flies were transferred to 27 degrees C. The implications for temperature effects on bluetongue epizootiology are discussed.
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Affiliation(s)
- B A Mullens
- University of California, Department of Entomology, Riverside 92521
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