RESUMO
AIM: To analyse repeated detection of West Nile virus (WNV) in mosquitoes in South Moravia in correlation with the first documented autochthonous human cases of West Nile fever (WNF), focusing on epidemiological and environmental investigation. MATERIALS AND METHODS: Here we report case studies of five patients with autochthonous WNF without any travel history diagnosed in South Moravia in 2018, along with in-depth epidemiological and environmental investigation. The cases were classified as confirmed based on the case definition criteria established in Commission Implementing Decision (EU) 2018/945. RESULTS: Between July and September 2018, a total of five human cases of West Nile virus infection were suspected and subsequently confirmed by the National Reference Laboratory for Arboviruses in Ostrava. All mosquito suspensions from the area where the first case of WNV infection was diagnosed tested WNV negative. CONCLUSIONS: WNV circulation in South Moravia has been known since 1997 when the first human cases (probably caused by WNV lineage 1) were confirmed after floods. The presence of more serious neuroinvasive lineage 2 (WNV-2), now circulating in central and eastern Europe, was detected repeatedly in 2013, 2015, and 2016 in Cx. modestus and Cx. pipiens mosquitoes within the scope of targeted entomological surveillance. These findings were published in 2016-2018 in both the professional press and mass media. It was only a matter of time and of making the correct differential diagnosis in patients with non-specific neuroinfections before there were confirmed autochthonous human cases of WNF caused by WNV-2. These presumptions were corroborated by epidemiological investigations performed by the staff of the Regional Public Health Authority of the South Moravian Region and Academy of Sciences.
Assuntos
Culicidae , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Culicidae/virologia , República Tcheca/epidemiologia , Humanos , Viagem , Febre do Nilo Ocidental/diagnóstico , Febre do Nilo Ocidental/epidemiologia , Vírus do Nilo Ocidental/fisiologiaRESUMO
Here we report repeated detection of lineage 2 West Nile virus (WNV-2) from Culex modestus and Cx. pipiens mosquitoes collected at fishponds in the Lednice-Valtice Area during the mosquito seasons 2015 and 2016. The WNV strains recovered share genetic homology with WNV strains isolated during an extensive monitoring in 2013 as well as with strains circulating in southern and central Europe at the same time. Repeated detection of WNV indicates its establishment in the area and also warns infection specialists and epidemiologists about possible emergence of human cases or even outbreaks of West Nile fever in the region.
Assuntos
Culex , Vírus do Nilo Ocidental , Animais , Culex/virologia , Europa (Continente) , Humanos , Insetos Vetores/virologia , Febre do Nilo Ocidental , Vírus do Nilo Ocidental/classificação , Vírus do Nilo Ocidental/genéticaRESUMO
We report the detection and isolation of four almost identical strains of West Nile virus (WNV) lineage 2from Culex modestus mosquitoes collected at three fish ponds in South Moravia, Czech Republic, during August 2013. Phylogenetic analysis demonstrated that the Czech WNV strains isolated are closely related to Austrian, Italian and Serbian strains reported in 2008,2011 and 2012, respectively. Our findings show the current northernmost range of lineage 2 WNV in Europe.
Assuntos
Culex/virologia , Vírus do Nilo Ocidental/genética , Vírus do Nilo Ocidental/isolamento & purificação , Animais , Culicidae/virologia , República Tcheca/epidemiologia , Doenças Endêmicas , Europa (Continente)/epidemiologia , Insetos Vetores/virologia , Itália , Dados de Sequência Molecular , Filogenia , Prevalência , RNA Viral/genética , RNA Viral/isolamento & purificação , Febre do Nilo Ocidental/epidemiologia , Vírus do Nilo Ocidental/classificaçãoRESUMO
Two strains of Tahyna virus (TAHV; Orthobunyavirus, Bunyaviridae) were isolated from 4,568 (92 pools) female Anopheles hyrcanus Pallas (Diptera, Culicidae) mosquitoes collected on the fishponds in South Moravia (Czechland, central Europe) during July-August 2013. This is the first isolation of TAHV from An. hyrcanus in Europe. An. hyrcanus is a species new to Czechland since 2007; its population density was very high in the year 2013 at these ponds. The virus isolation procedure was based on intracerebral inoculation of newborn mice; moreover, the positive pools were also tested by polymerase chain reaction and found to contain TAHV RNA. An. hyrcanus, feeding preferentially on mammals including humans, may be a new potential vector for TAHV in Europe.
Assuntos
Anopheles/virologia , Vírus da Encefalite da Califórnia/isolamento & purificação , Mosquitos Vetores/virologia , Animais , República Tcheca , Feminino , CamundongosRESUMO
Between July and September 2012, seventeen larvae of the invasive mosquito species Aedes (Stegomyia) albopictus (Skuse) were discovered using 60 ovitraps at four study sites alongside two main road exits in South Moravia, Czech Republic. This is the first report of imported Ae. albopictus in the Czech Republic. The findings highlight the need for a regular surveillance programme to monitor this invasive species throughout western and central Europe.
Assuntos
Aedes/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Insetos Vetores/crescimento & desenvolvimento , Aedes/virologia , Animais , República Tcheca/epidemiologia , Demografia , Dengue/epidemiologia , Dengue/transmissão , Dengue/virologia , Vírus da Dengue/crescimento & desenvolvimento , Insetos Vetores/virologia , Larva/crescimento & desenvolvimento , Controle de Mosquitos/métodos , Oviposição , Filogeografia , Estações do Ano , Especificidade da EspécieRESUMO
Mosquito collections with CDC light traps using dry ice and pigeon-baited traps were carried out in south Moravia (Czech Republic) from April to October in 2007 and 2008 at two study sites. In 2007, 11 two-day captures were carried out in two-week intervals, and 1,490 female mosquitoes of nine species were caught. In 2008, 15 two-day trappings of mosquitoes were carried out: 6,778 females of 22 species of mosquitoes were trapped. The results showed marked differences in abundance and species composition of mosquitoes between both study sites and between the trapping methods. In the floodplain forest ecosystem of the Soutok study area, Aedes vexans predominated. The species composition in the Nesyt study site was more varied and the most common species was Culex pipiens. At the latter study site, Anopheles hyrcanus (var. pseudopictus) and Uranotaenia unguiculata, mosquito species with largely southern Eurasian distribution, were repeatedly demonstrated. The largest capture of mosquitoes was in traps with CO2 placed at a height 1 m above the ground. The capture of mosquitoes in the pigeon-baited traps as well as in the traps with CO2 placed in the canopy of trees was markedly lower in both study sites, with the predominant species being Culex pipiens.
Assuntos
Culicidae/crescimento & desenvolvimento , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/transmissão , Aedes/crescimento & desenvolvimento , Aedes/virologia , Animais , Anopheles/crescimento & desenvolvimento , Anopheles/virologia , Culicidae/virologia , GeografiaRESUMO
Six viral isolates were obtained from 23,243 female mosquitoes (examined in 513 pools) belonging to 16 species and collected along the lower reaches of the Dyje River in South Moravia (Czech Republic, central Europe) during 2006-2008: five isolates of Orthobunyavirus Tahyna (TAHV, California group, family Bunyaviridae: three isolations from Aedes vexans (Meigen), one from Ae. sticticus (Meigen), one from Culex modestus Ficalbi); and one isolation of Flavivirus West Nile (WNV, Japanese encephalitis group, family Flaviviridae)-strain Rabensburg (proposed lineage 3 of WNV) from Ae. rossicus (Dolbeshkin et al). All viral isolates were recovered from mosquitoes collected in 2006 (15,882 mosquitoes examined), while no virus was isolated from mosquitoes trapped in 2007 and 2008, when 1,555 and 5,806 mosquitoes were examined, respectively. The population density of local mosquitoes was very low in 2007 and 2008 because of warm and dry summer including a considerably low water table, compared with environmental conditions favorable for mosquito development in 2006. The virus isolation procedure was based on intracerebral inoculation of newborn mice. In parallel, more than one-third of the samples (183 pools consisting of 8,470 individual mosquitoes) were also examined by inoculating Vero cell cultures in Leighton tubes. However, the latter method detected only three of the six virus isolates (including WNV-Rabensburg). Ae. rossicus is a new potential vector for WNV-Rabensburg. This species feeds mostly on mammals including man; this raises the question whether this virus lineage is not adapted to an alternative mosquito-mammal cycle in the South-Moravian natural focus.
Assuntos
Arbovírus/genética , Culicidae/virologia , Substituição de Aminoácidos , Animais , Arbovírus/isolamento & purificação , Culex/virologia , República Tcheca , Primers do DNA , Vírus da Encefalite da Califórnia/genética , Vírus da Encefalite da Califórnia/isolamento & purificação , Feminino , Masculino , Camundongos/virologia , Polimorfismo de Nucleotídeo Único , RNA Viral/genética , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas Virais/genética , Febre do Nilo Ocidental/mortalidade , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/genética , Vírus do Nilo Ocidental/isolamento & purificaçãoRESUMO
During a survey of mosquitoes in the South Moravian lowland area, the mosquito Anopheles hyrcanus (Pallas) (Diptera: Culicidae) was found breeding in an ancient fishpond (Nesyt). It is not clear whether this southern Palaearctic species, a known vector of malaria in Asia which has not been recorded in the Czech Republic until this year, has gone undetected in the past or whether it has recently moved into the region as a result of climate change.
Assuntos
Anopheles/fisiologia , Água/parasitologia , Animais , Clima , República Tcheca , Ecossistema , Feminino , Malária/epidemiologia , Malária/parasitologia , Masculino , Densidade Demográfica , Estações do AnoRESUMO
In July 1997, devastating floods occurred after heavy rains in Moravia, Czech Republic. Mosquito populations increased abruptly in the flooded area thereafter. We carried out a surveillance for mosquito-borne virus infections in the Breclav area, South Moravia, including serosurveys of inhabitants. A total of 11,334 female mosquitoes in 117 pools (9,100 Aedes vexans, 917 A. cinereus, 11 A. cantans, 1,074 A. sticticus and 232 Culex pipiens pipiens) were examined by virological methods. Seven virus isolates were obtained: six of them Tahyna virus (Aedes vexans 5, A. cinereus 1), while one was West Nile (WN) virus (Culex p. pipiens--first isolation in the Czech Republic). Sera of 619 local inhabitants were examined in plaque-reduction neutralization test, and antibodies to Tahyna virus were detected in 333 (53.8%) and to WN virus in 13 (2.1%). In 72 individuals, paired sera were sampled: a significant increase of antibody titre was detected once against Tahyna virus (a subclinical infection) and 4 times against WN virus (two children had an illness compatible with WN fever). Of the nine remaining WN seroreactors, three other revealed clinical symptoms compatible with WN fever in summer 1997. The data indicate WN virus activity in the Breclav area, and describe the first cases of WN fever in Central Europe. The WN virus should not be underestimated as a potential agent of local epidemics even in the temperate climate of Central Europe. Environmental factors including human activities which enhance vector population densities (heavy rains followed by floods, irrigation, higher temperature) can produce an increased incidence of mosquito-borne diseases, including WN fever.