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Integrated Human Surveillance Systems of West Nile Virus Infections in Italy: The 2012 Experience  [PDF]
Christian Napoli,Antonino Bella,Silvia Declich,Giuliano Grazzini,Letizia Lombardini,Alessandro Nanni Costa,Loredana Nicoletti,Maria Grazia Pompa,Simonetta Pupella,Francesca Russo,Caterina Rizzo
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10127180
Abstract: In Italy, a West Nile virus (WNV) surveillance plan was firstly implemented in 2008 and 2009 in two affected regions and, since 2010, according to a national plan, a WNV neuroinvasive disease (WNND) surveillance has to be carried out each year during the period 15 June–30 November, in those regions where WNV circulation has been demonstrated among humans, animals or vectors. Moreover, since WNV can be transmitted to humans even by blood transfusions and organ transplants obtained from infected donors, the national surveillance integrates the blood transfusions and organs transplant surveillances too. The paper describes the results of this integrated human surveillance in Italy in 2012. Overall, in 2012, 28 autochthonous confirmed cases of WNND were reported, 14 blood donations were found WNV positive by Nucleic Acid Amplification Test and no solid organ donors tested positive for WNV. Moreover, 17 cases of WNV fever were confirmed in Veneto region. When comparing the number of WNND cases reported to the surveillance system in previous 4 years (43 cases during the period 2008–2011), with those reported in 2012 an important increase was observed in 2012. The geographic distribution of human cases was consistent with the WNV circulation among animals and vectors. Moreover, the implementation of preventive measures for WNV transmission through blood components allowed the detection of blood donors positive for WNV, avoiding the further spread of the disease. Since surveillance strategies and preventive measures are based on the integration among human, animal and vector control activities, the Italian experience could be considered a good example of collaboration among different sectors of public health in a “one health” perspective.
First report on entomological field activities for the surveillance of West Nile disease in Italy
Luciano Toma,Micaela Cipriani,Maria Goffredo,Roberto Romi
Veterinaria Italiana , 2008,
Abstract: West Nile virus (WNV) is neuropathogenic for birds, horses and humans and is maintained in natural cycles between birds and mosquitoes, particularly the Culex genus; horses and humans are considered to be incidental hosts. A surveillance plan was implemented in Italy in 1998, following a limited outbreak of WNV equine encephalomyelitis and a WNV outbreak in France very close to the Italian border. This plan to assess the risks of the virus being introduced again included entomological surveillance performed in 15 study areas considered ‘at risk’ of WNV introduction in the country. Entomological surveys conducted in Italy from 2003 to 2007 resulted in the capture of a total of 28 798 mosquitoes, of which there were 14 765 adults and 14 033 larvae belonging to 22 species. According to the literature, eight of the species identified have been found to be naturally infected with WNV or were successfully infected in the laboratory in some parts of Europe and in the United States, namely: Aedes albopictus (Skuse, 1897) (= Stegomiya albopicta), Aedes vexans (Meigen, 1830), Anopheles maculipennis Meigen, 1818, Coquillettidia richiardii (Ficalbi, 1889), Culex modestus Ficalbi, 1889, Culex pipiens Linnaeus, 1758, Culex theileri Theobald, 1903 and Ochlerotatus caspius (Pallas, 1771) (= Aedes caspius).
Further spread of West Nile virus in Italy  [PDF]
Paolo Calistri,Federica Monaco,Giovanni Savini,Annalisa Guercio
Veterinaria Italiana , 2010,
Abstract: Following two consecutive years of West Nile virus (WNV) circulation in Italy, new foci of infection were observed in August 2010 in Sicily and Molise in southern and central Italy, respectively. These incidents were far from the previous infected area in northern Italy, thereby confirming the ability of WNV to spread to new areas and affect new host populations.
The Complex Epidemiological Scenario of West Nile Virus in Italy  [PDF]
Luisa Barzon,Monia Pacenti,Elisa Franchin,Laura Squarzon,Enrico Lavezzo,Margherita Cattai,Riccardo Cusinato,Giorgio Palù
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10104669
Abstract: Entomological, veterinary, and human surveillance systems for West Nile virus (WNV) infection have been implemented in Italy since the first detection of the virus in 1998. These surveillance activities documented a progressive increase of WNV activity and spread in different regions and the emergence of new WNV lineages and strains. Italy is a paradigmatic example of the complex epidemiology of WNV in Europe, where sporadic cases of WNV infection, clusters, and small outbreaks have been reported in several regions. In addition, different strains of both WNV lineage 1 and lineage 2 have been identified, even co-circulating in the same area.
Evidence of Simultaneous Circulation of West Nile and Usutu Viruses in Mosquitoes Sampled in Emilia-Romagna Region (Italy) in 2009  [PDF]
Mattia Calzolari,Paolo Bonilauri,Romeo Bellini,Alessandro Albieri,Francesco Defilippo,Giulia Maioli,Giorgio Galletti,Antoni Gelati,Ilaria Barbieri,Marco Tamba,Davide Lelli,Elena Carra,Paolo Cordioli,Paola Angelini,Michele Dottori
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014324
Abstract: In recent years human diseases due to mosquito-borne viruses were increasingly reported in Emilia-Romagna region (Italy), from the chikungunya virus in 2007 to the West Nile virus (WNV) in 2008. An extensive entomological survey was performed in 2009 to establish the presence and distribution of mosquito arboviruses in this region, with particular reference to flaviviruses.
Genome Sequencing of West Nile Virus from Human Cases in Greece, 2012  [PDF]
Luisa Barzon,Anna Papa,Monia Pacenti,Elisa Franchin,Enrico Lavezzo,Laura Squarzon,Giulia Masi,Thomas Martello,Theodolinta Testa,Riccardo Cusinato,Giorgio Palù
Viruses , 2013, DOI: 10.3390/v5092311
Abstract: A West Nile Virus (WNV) lineage 2 strain, named Nea Santa-Greece-2010, has been demonstrated to be responsible for the large outbreaks of neuroinvasive disease (WNND) that have been occurring in Greece since 2010, based on sequence similarities of viral isolates identified between 2010–2012. However, knowledge on the evolution of this strain is scarce because only partial WNV genome sequences are available from Greece. The aim of this study was to get the complete genome sequence of WNV from patients with infection. To this aim, plasma and urine samples collected during the 2012 Greek outbreak were retrospectively investigated. Full WNV genome sequence was obtained from a patient with WNND. The genome had 99.7% sequence identity to Nea Santa, higher than to other related WNV lineage 2 strains, and five amino acid changes apparently not relevant for viral pathogenicity or fitness. In addition, infection by WNV lineage 2 was confirmed in additional nine patients with WNND; in three of them the infection with WNV Nea Santa was demonstrated by sequencing. In conclusion, this study characterized for the first time a WNV full genome from a patient with WNND from Greece, demonstrated the persistence of the Nea Santa strain, and suggested that the virus might have locally evolved.
Recent progress in West Nile virus diagnosis and vaccination
Marina De Filette, Sebastian Ulbert, Michael S Diamond, Niek N Sanders
Veterinary Research , 2012, DOI: 10.1186/1297-9716-43-16
Abstract: 1. Introduction2. West Nile virus3. Epidemiology4. Pathogenesis5. Diagnosis5.1. Nucleic acid based tests for WNV5.2. Serologic diagnosis of WNV infections5.3. WNV antigen detection6. Vaccination6.1. Licensed West Nile virus vaccines for animals6.2. WNV vaccines under development6.3. Clinical trials with West Nile virus vaccines in humans7. Conclusions8. Competing interests9. Authors' contributions10. Acknowledgments11. ReferencesWest Nile virus (WNV) is a zoonotic mosquito-transmitted arbovirus belonging to the genus Flavivirus in the family Flaviviridae. WNV is maintained in a mosquito-bird-mosquito transmission cycle [1], whereas humans and horses are considered dead-end hosts. WNV is transmitted primarily by the bite of infected mosquitoes, themselves acquiring the virus by feeding on infected birds.The West Nile virus has been reported in dead or dying birds of at least 326 species [2]. The clinical outcome of infection is variable e.g. chickens and turkeys are resistant to disease while some species are particularly susceptible, e.g. crows, Carolina chickadees, tufted titmice, blue jays, American robins, and eastern bluebirds.WNV has a wide geographical range that includes portions of Europe, Asia, Africa, Australia (Kunjin virus) and North, Central and South America [3]. Migratory birds are thought to be primarily responsible for virus dispersal, including reintroduction of WNV from endemic areas into regions that experience sporadic outbreaks [3].In humans, it was first isolated in the West Nile province of Uganda in 1937 from the blood of a woman suffering from a mild febrile illness [4]. Until the mid 1990's, West Nile (WN) disease was considered as a minor risk for humans and horses because it only appeared sporadically. The first cases of West Nile virus in its lethal encephalitic form were reported in Algeria in 1994. Since the first large outbreak in Romania in 1996, which was characterized by a high number of neuroinvasive cases, and the huge epidemics
Genetic Analysis of West Nile Virus Isolates from an Outbreak in Idaho, United States, 2006–2007  [PDF]
Andriyan Grinev,Caren Chancey,Germán A?ez,Christopher Ball,Valerie Winkelman,Phillip Williamson,Gregory A. Foster,Susan L. Stramer,Maria Rios
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10094486
Abstract: West Nile virus (WNV) appeared in the U.S. in 1999 and has since become endemic, with yearly summer epidemics causing tens of thousands of cases of serious disease over the past 14 years. Analysis of WNV strains isolated during the 2006–2007 epidemic seasons demonstrates that a new genetic variant had emerged coincidentally with an intense outbreak in Idaho during 2006. The isolates belonging to the new variant carry a 13 nt deletion, termed ID-Δ13, located at the variable region of the 3′UTR, and are genetically related. The analysis of deletions and insertions in the 3′UTR of two major lineages of WNV revealed the presence of conserved repeats and two indel motifs in the variable region of the 3′UTR. One human and two bird isolates from the Idaho 2006–2007 outbreaks were sequenced using Illumina technology and within-host variability was analyzed. Continued monitoring of new genetic variants is important for public health as WNV continues to evolve.
West Nile Virus in the United States — A Historical Perspective  [PDF]
John T. Roehrig
Viruses , 2013, DOI: 10.3390/v5123088
Abstract: Prior to 1999, West Nile virus (WNV) was a bit player in the screenplay of global vector-borne viral diseases. First discovered in the West Nile District of Uganda in 1937, this Culex sp.-transmitted virus was known for causing small human febrile outbreaks in Africa and the Middle East. Prior to 1995, the last major human WNV outbreak was in the 1950s in Israel. The epidemiology and ecology of WNV began to change in the mid-1990s when an epidemic of human encephalitis occurred in Romania. The introduction of WNV into Eastern Europe was readily explained by bird migration between Africa and Europe. The movement of WNV from Africa to Europe could not, however, predict its surprising jump across the Atlantic Ocean to New York City and the surrounding areas of the United States (U.S.). This movement of WNV from the Eastern to Western Hemisphere in 1999, and its subsequent dissemination throughout two continents in less than ten years is widely recognized as one of the most significant events in arbovirology during the last two centuries. This paper documents the early events of the introduction into and the spread of WNV in the Western Hemisphere.
Environmental and social determinants of human risk during a West Nile virus outbreak in the greater Chicago area, 2002
Marilyn O Ruiz, Carmen Tedesco, Thomas J McTighe, Connie Austin, Uriel Kitron
International Journal of Health Geographics , 2004, DOI: 10.1186/1476-072x-3-8
Abstract: The cluster pattern of high incidence of cases was statistically significant. The risk factors that were found to be important included the presence of vegetation, age, income, and race of the human population, distance to a WNV positive dead bird specimen, age of housing, mosquito abatement and geological factors. The effect of different mosquito abatement efforts was particularly notable. About 53 percent of the variation of the location of WNV clusters was explained by these factors.The models developed indicate that differential mosquito abatement efforts are especially important risk factors, even when controlling for key environmental factors. Human population characteristics play a role in risk that is measurable in this ecological study but would require further research to associate causality with risk. The analysis of spatial clusters of case incidence indicates that this approach provides more insight into the focal nature of differential risk factors that tend to be associated with WNV than an analysis of all individual cases.West Nile Virus (WNV) was first identified in the United States in samples from infected birds, humans, mosquitoes and horses in and around New York City during the fall of 1999 [1]. Since 1999, the West Nile virus has most probably become established as an enzootic virus with annual occurrence of human cases [2,3]. West Nile virus is similar to other viruses in the Japanese encephalitis virus complex, which includes St. Louis encephalitis (SLE), which also occurs in the United States. The virus cycles between birds and mosquitoes; while horses, humans and a number of other vertebrates are considered incidental hosts. Elderly people are more susceptible to severe forms of infection and many people infected will have only minor symptoms or remain asymptomatic [4]. While many avian species have tested positive for WNV, only species that develop sufficiently high levels of viremia will promote transmission of the virus to mosquitoes. T
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