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Parasites & Vectors Sep 2016West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause unforeseen and large epidemics. Until 2004, only lineage 1... (Review)
Review
West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause unforeseen and large epidemics. Until 2004, only lineage 1 and 3 WNV strains had been found in Europe. Lineage 2 strains were initially isolated in 2004 (Hungary) and in 2008 (Austria) and for the first time caused a major WNV epidemic in 2010 in Greece with 262 clinical human cases and 35 fatalities. Since then, WNV lineage 2 outbreaks have been reported in several European countries including Italy, Serbia and Greece. Understanding the interaction of ecological factors that affect WNV transmission is crucial for preventing or decreasing the impact of future epidemics. The synchronous co-occurrence of competent mosquito vectors, virus, bird reservoir hosts, and susceptible humans is necessary for the initiation and propagation of an epidemic. Weather is the key abiotic factor influencing the life-cycles of the mosquito vector, the virus, the reservoir hosts and the interactions between them. The purpose of this paper is to review and compare mosquito population dynamics, and weather conditions, in three ecologically different contexts (urban/semi-urban, rural/agricultural, natural) across four European countries (Italy, France, Serbia, Greece) with a history of WNV outbreaks. Local control strategies will be described as well. Improving our understanding of WNV ecology is a prerequisite step for appraising and optimizing vector control strategies in Europe with the ultimate goal to minimize the probability of WNV infection.
Topics: Animals; Culicidae; Ecology; Europe; Humans; Mosquito Vectors; West Nile Fever; West Nile virus
PubMed: 27590848
DOI: 10.1186/s13071-016-1736-6 -
Journal of the American Mosquito... Mar 2018West Nile virus (WNV) was first detected in North America during 1999, and has since spread throughout the contiguous USA. West Nile virus causes West Nile fever and the...
West Nile virus (WNV) was first detected in North America during 1999, and has since spread throughout the contiguous USA. West Nile virus causes West Nile fever and the more severe West Nile neuroinvasive disease. As part of a WNV vector surveillance program, we collected mosquitoes in Lubbock, Texas, using CO-baited encephalitic vector survey (EVS) traps. During 219 wk from 2009 through 2017, EVS traps were operated for 1,748 trap nights, resulting in more than 101,000 mosquitoes captured. Weekly, selected female mosquito specimens were pooled by species and trap site, and screened for WNV using reverse transcription-polymerase chain reaction assay. Mosquitoes positive for WNV were detected during 16.9% (37/219) of the weeks. Using this information, we constructed a statistical model to predict the probability of detecting an infection within a mosquito pool as a factor of weather variables. The final model indicated that detection of WNV in mosquitoes was negatively associated with the week of year squared and average wind from 3 wk prior to sampling, and was positively associated with week of year, average visibility, average humidity from 2 wk prior to sampling, and average dew point from 4 wk prior to sampling. The model developed in this study may aid public health and vector control programs in swift and effective decision making relative to city-wide mosquito control efforts by predicting when the chances of mosquitoes having WNV are at their greatest.
Topics: Animals; Cities; Culicidae; Epidemiological Monitoring; Female; Models, Biological; Mosquito Control; Mosquito Vectors; Texas; West Nile Fever; West Nile virus
PubMed: 31442123
DOI: 10.2987/17-6714.1 -
Journal of Medical Entomology Oct 2019The introduction of West Nile virus to North America in 1999 had profound impacts on human and wildlife health. Here, we review studies of WNV impacts on bird... (Review)
Review
The introduction of West Nile virus to North America in 1999 had profound impacts on human and wildlife health. Here, we review studies of WNV impacts on bird populations and find that overall impacts have been less than initially anticipated, with few species showing sustained changes in population size or demographic rates across multiple regions. This raises four questions: 1) What is the evidence for WNV impact on bird populations and how can we strengthen future analyses? We argue that future studies of WNV impacts should explicitly incorporate temporal variation in WNV transmission intensity, integrate field data with laboratory experimental infection studies, and correct for multiple comparisons. 2) What mechanisms might explain the relatively modest impact of WNV on most bird populations? We suggest that spatial and temporal variation in WNV transmission moderates WNV impacts on species that occur in multiple habitats, some of which provide refugia from infection. 3) Have species recovered from the initial invasion of WNV? We find evidence that many species and populations have recovered from initial WNV impact, but a few have not. 4) Did WNV cause cascading effects on other species and ecosystems? Unfortunately, few studies have examined the cascading effects of WNV population declines, but evidence suggests that some species may have been released from predation or competition. We close by discussing potentially overlooked groups of birds that may have been affected by WNV, and one highlight species, the yellow-billed magpie (Pica nutalli Audubon, 1837 [Passeriformes: Corvidae]), that appears to have suffered the largest range-wide impact from WNV.
Topics: Animals; Bird Diseases; Birds; North America; Population Dynamics; Species Specificity; West Nile Fever; West Nile virus
PubMed: 31549723
DOI: 10.1093/jme/tjz149 -
The Primary Care Companion For CNS... Apr 2023
Topics: Humans; West Nile virus; Catatonia; Psychotic Disorders
PubMed: 37058713
DOI: 10.4088/PCC.22cr03379 -
Viruses Nov 2019We reviewed the literature on the role of temperature in transmission of zoonotic arboviruses. Vector competence is affected by both direct and indirect effects of... (Review)
Review
We reviewed the literature on the role of temperature in transmission of zoonotic arboviruses. Vector competence is affected by both direct and indirect effects of temperature, and generally increases with increasing temperature, but results may vary by vector species, population, and viral strain. Temperature additionally has a significant influence on life history traits of vectors at both immature and adult life stages, and for important behaviors such as blood-feeding and mating. Similar to vector competence, temperature effects on life history traits can vary by species and population. Vector, host, and viral distributions are all affected by temperature, and are generally expected to change with increased temperatures predicted under climate change. Arboviruses are generally expected to shift poleward and to higher elevations under climate change, yet significant variability on fine geographic scales is likely. Temperature effects are generally unimodal, with increases in abundance up to an optimum, and then decreases at high temperatures. Improved vector distribution information could facilitate future distribution modeling. A wide variety of approaches have been used to model viral distributions, although most research has focused on the West Nile virus. Direct temperature effects are frequently observed, as are indirect effects, such as through droughts, where temperature interacts with rainfall. Thermal biology approaches hold much promise for syntheses across viruses, vectors, and hosts, yet future studies must consider the specificity of interactions and the dynamic nature of evolving biological systems.
Topics: Animals; Arboviruses; Climate Change; Disease Vectors; Ecosystem; Mosquito Vectors; Species Specificity; Temperature; Vector Borne Diseases; West Nile virus
PubMed: 31683823
DOI: 10.3390/v11111013 -
Viruses Jan 2020The West Nile virus is endemic in multiple European countries and responsible for several epidemics throughout the European region. Its evolution into local or even...
The West Nile virus is endemic in multiple European countries and responsible for several epidemics throughout the European region. Its evolution into local or even widespread epidemics is driven by multiple factors from genetic diversification of the virus to environmental conditions. The year of 2018 was characterized by an extraordinary increase in human and animal cases in the Central-Eastern European region, including Hungary. In a collaborative effort, we summarized and analyzed the genetic and serologic data of WNV infections from multiple Hungarian public health institutions, universities, and private organizations. We compared human and veterinary serologic data, along with NS5 and NS3 gene sequence data through 2018. Wild birds were excellent indicator species for WNV circulation in each year. Our efforts resulted in documenting the presence of multiple phylogenetic subclades with Balkans and Western-European progenitor sequences of WNV circulating among human and animal populations in Hungary prior to and during the 2018 epidemic. Supported by our sequence and phylogenetic data, the epidemic of 2018 was not caused by recently introduced WNV strains. Unfortunately, Hungary has no country-wide integrated surveillance system which would enable the analysis of related conditions and provide a comprehensive epidemiological picture. The One Health approach, involving multiple institutions and experts, should be implemented in order to fully understand ecological background factors driving the evolution of future epidemics.
Topics: Animals; Antigens, Viral; Birds; Encephalitis; Epidemics; Genes, Viral; Hawks; Horses; Humans; Hungary; One Health; Pathology, Molecular; Phylogeny; Seroepidemiologic Studies; Viral Nonstructural Proteins; Viral Proteins; West Nile Fever; West Nile virus
PubMed: 31968613
DOI: 10.3390/v12010123 -
Frontiers in Cellular and Infection... 2019West Nile and dengue viruses are closely related flaviviruses, originating mosquito-borne viral infections for which there are no effective and specific treatments....
West Nile and dengue viruses are closely related flaviviruses, originating mosquito-borne viral infections for which there are no effective and specific treatments. Their capsid proteins sequence and structure are particularly similar, forming highly superimposable α-helical homodimers. Measuring protein-ligand interactions at the single-molecule level yields detailed information of biological and biomedical relevance. In this work, such an approach was successfully applied on the characterization of the West Nile virus capsid protein interaction with host lipid systems, namely intracellular lipid droplets (an essential step for dengue virus replication) and blood plasma lipoproteins. Dynamic light scattering measurements show that West Nile virus capsid protein binds very low-density lipoproteins, but not low-density lipoproteins, and this interaction is dependent of potassium ions. Zeta potential experiments show that the interaction with lipid droplets is also dependent of potassium ions as well as surface proteins. The forces involved on the binding of the capsid protein with lipid droplets and lipoproteins were determined using atomic force microscopy-based force spectroscopy, proving that these interactions are K-dependent rather than a general dependence of ionic strength. The capsid protein interaction with host lipid systems may be targeted in future therapeutic strategies against different flaviviruses. The biophysical and nanotechnology approaches employed in this study may be applied to characterize the interactions of other important proteins from different viruses, in order to understand their life cycles, as well as to find new strategies to inhibit them.
Topics: Animals; Capsid Proteins; Cell Line; Cricetinae; Host-Pathogen Interactions; Humans; Lipid Droplets; Lipid Metabolism; Lipoproteins, VLDL; Protein Binding; West Nile virus
PubMed: 30788291
DOI: 10.3389/fcimb.2019.00008 -
Parasites & Vectors Oct 2018West Nile virus (WNV) is endemic in southeastern Romania and, after the unprecedented urban epidemic in Bucharest in 1996 caused by lineage 1 WNV, cases of West Nile...
BACKGROUND
West Nile virus (WNV) is endemic in southeastern Romania and, after the unprecedented urban epidemic in Bucharest in 1996 caused by lineage 1 WNV, cases of West Nile fever have been recorded every year. Furthermore, a new outbreak occurred in 2010, this time produced by a lineage 2 WNV belonging to the Eastern European clade (Volgograd 2007-like strain), which was detected in humans and mosquitoes in the following years.
RESULTS
We report here, for the first time, the emergence, in 2015, of lineage 2 WNV belonging to the monophyletic Central/Southern European group of strains which replaced in 2016, the previously endemized lineage 2 WNV Volgograd 2007-like strain in mosquito populations. The emerged WNV strain harbors H249P (NS3 protein) and I159T (E glycoprotein) substitutions, which have been previously associated in other studies with neurovirulence and efficient vector transmission.
CONCLUSIONS
In 2016, both early amplification of the emerged WNV and complete replacement in mosquito populations of the previously endemized WNV occurred in southeastern Romania. These events were associated with a significant outbreak of severe West Nile neuroinvasive disease in humans.
Topics: Animals; Culicidae; Disease Outbreaks; Epidemics; Humans; Mosquito Vectors; Phylogeny; Romania; West Nile Fever; West Nile virus
PubMed: 30367671
DOI: 10.1186/s13071-018-3145-5 -
Viruses Feb 2018West Nile virus (WNV) and Usutu virus (USUV) are members of the family Flaviviridae which, natural life cycles involve mosquito-bird-mosquito transmission. Both...
West Nile virus (WNV) and Usutu virus (USUV) are members of the family Flaviviridae which, natural life cycles involve mosquito-bird-mosquito transmission. Both represent emerging viruses in Europe with potential to cause neuroinvasive disease in humans. This study investigates the seroprevalence of serum neutralizing antibodies to WNV and to USUV in birds and in horses in Poland. Antibodies against WNV and USUV were detected in 5 (35.7%) and in 1 (7.14%) of 14 birds and in 62 (15.08%) and in 115 (27.98%) of 411 horses, respectively. Twenty-one WNV serologically positive horses (33.87%) and 67 USUV serologically positive horses (58.26%) did not travel outside Polish borders. Given the high abundance of potentially competent mosquito species in Poland, high populations of horses and different bird species, our findings highlight implementation of active control programs, including monitoring of geographic spread and dynamics of WNV and USUV transmission in both primary and accidental hosts. It is also important to improve public health awareness about the disease these viruses may cause.
Topics: Animals; Bird Diseases; Child, Preschool; Horse Diseases; Horses; Humans; Poland; Seroepidemiologic Studies; West Nile Fever; West Nile virus
PubMed: 29462983
DOI: 10.3390/v10020087 -
Parasites & Vectors Mar 2017Active vector surveillance provides an efficient tool for monitoring the presence or spread of emerging or re-emerging vector-borne viruses. This study was undertaken to...
BACKGROUND
Active vector surveillance provides an efficient tool for monitoring the presence or spread of emerging or re-emerging vector-borne viruses. This study was undertaken to investigate the circulation of flaviviruses. Mosquitoes were collected from 58 locations in 10 provinces across the Aegean, Thrace and Mediterranean Anatolian regions of Turkey in 2014 and 2015. Following morphological identification, mosquitoes were pooled and screened by nested and real-time PCR assays. Detected viruses were further characterised by sequencing. Positive pools were inoculated onto cell lines for virus isolation. Next generation sequencing was employed for genomic characterisation of the isolates.
RESULTS
A total of 12,711 mosquito specimens representing 15 species were screened in 594 pools. Eleven pools (2%) were reactive in the virus screening assays. Sequencing revealed West Nile virus (WNV) in one Culex pipiens (s.l.) pool from Thrace. WNV sequence corresponded to lineage one clade 1a but clustered distinctly from the Turkish prototype isolate. In 10 pools, insect-specific flaviviruses were characterised as Culex theileri flavivirus in 5 pools of Culex theileri and one pool of Cx. pipiens (s.l.), Ochlerotatus caspius flavivirus in two pools of Aedes (Ochlerotatus) caspius, Flavivirus AV-2011 in one pool of Culiseta annulata, and an undetermined flavivirus in one pool of Uranotaenia unguiculata from the Aegean and Thrace regions. DNA forms or integration of the detected insect-specific flaviviruses were not observed. A virus strain, tentatively named as "Ochlerotatus caspius flavivirus Turkey", was isolated from an Ae. caspius pool in C6/36 cells. The viral genome comprised 10,370 nucleotides with a putative polyprotein of 3,385 amino acids that follows the canonical flavivirus polyprotein organisation. Sequence comparisons and phylogenetic analyses revealed the close relationship of this strain with Ochlerotatus caspius flavivirus from Portugal and Hanko virus from Finland. Several conserved structural and amino acid motifs were identified.
CONCLUSIONS
We identified WNV and several distinct insect-specific flaviviruses during an extensive biosurveillance study of mosquitoes in various regions of Turkey in 2014 and 2015. Ongoing circulation of WNV is revealed, with an unprecedented genetic diversity. A probable replicating form of an insect flavivirus identified only in DNA form was detected.
Topics: Aedes; Animals; Culex; Flavivirus; Flavivirus Infections; Genetic Variation; Genome, Viral; Humans; Insect Vectors; Phylogeny; Species Specificity; Turkey; West Nile Fever; West Nile virus
PubMed: 28320443
DOI: 10.1186/s13071-017-2087-7