6 research outputs found
P03.2 Preliminary analyses of two floodwater mosquito populations and Earth Observation data (Sentinel2 spectral bands) in collection sites in Central Italy
No full textVector presence and population dynamics are strongly linked to climatic factors (Chevalier et al., 2004), which consequently can have an impact on the transmission of vector borne diseases. In particular, the abundance of floodwater mosquitoes results from the successive waves of adult emergences due to different flooding of the breeding sites (Becker et al., 2010). Floodwater mosquitoes (e.g. Aedes vexans and Aedes caspius) commonly reach high abundance levels, causing tremendous nuisance in the near and far surroundings, and possibly acting as vectors of arboviruses (e.g. Rift Valley Fever and West Nile viruses). In this preliminary analysis, the abundance of floodwater mosquitoes, determined by field data collections, was compared with Earth Observation data of the same area.
The field data were collected during an intensive and systematic entomological surveillance, carried out in Abruzzo and Molise Regions, as part of the National Plan for prevention, surveillance and response to West Nile and Usutu viruses, and other research projects. The field activity was carried out in four mosquito seasons (2019 – 2022) from May to November; the insect collections were performed weekly or biweekly, using CDC-light traps baited with CO2. Overall, 2,145 collections were made in 60 collection sites and almost 45,000 mosquitoes were morphologically identified, belonging to the 7 genera present in Italy and to 20 different species. Basing on the abundance of floodwater mosquitoes, two collection sites were selected to for this study: Campomarino (Molise Region), where 87.1% of collected mosquitoes belongs to Aedes caspius, and Altino (Abruzzo Region), where Aedes vexans shows its highest abundance. The two sites are close to a marshy area and a river, respectively.
To catch the local characteristics of the possible mosquito breeding sites, the field data collected in two sites were compared with high resolution images by means of the Normalized Difference Water Index (NDWI) trend, using the free web application EO browser (https://www.sentinel-hub.com/explore/eobrowser/) and selecting the time range relevant for mosquito emergence. NDWI index is used to monitor changes related to water content in water bodies, using green and near infrared bands of the electromagnetic spectrum (McFeeters, 1996). Abundance peaks of the two mosquito populations were detected approximately 3 weeks after the increase in water surface, following periods of drought.
This work is a preliminary attempt to use Sentinel-2 data to explain trend/abundance in two mosquito species in central Italy. Limitations due to differences in timing among mosquito collections, satellite passages, cloud coverage, should be considered in further analyses, as well as integration of other data and sources.
Understanding the main drivers leading to abundance peaks of mosquito population would be helpful to focus vector control programs. In this perspective, new insights could derive using new satellite imagery
The Absence of Abdominal Pigmentation in Livestock Associated Culicoides following Artificial Blood Feeding and the Epidemiological Implication for Arbovirus Surveillance
No full textCulicoides midges (Diptera: Ceratopogonidae), the vectors of economically important arboviruses such as bluetongue virus and African horse sickness virus, are of global importance. In the absence of transovarial transmission, the parity rate of a Culicoides population provides imperative information regarding the risk of virus dispersal. Abdominal pigmentation, which develops after blood feeding and ovipositioning, is used as an indicator of parity in Culicoides. During oral susceptibility trials over the last three decades, a persistent proportion of blood engorged females did not develop pigment after incubation. The present study, combining a number of feeding trials and different artificial feeding methods, reports on this phenomenon, as observed in various South African and Italian Culicoides species and populations. The absence of pigmentation in artificial blood-fed females was found in at least 23 Culicoides species, including important vectors such as C. imicola, C. bolitinos, C. obsoletus, and C. scoticus. Viruses were repeatedly detected in these unpigmented females after incubation. Blood meal size seems to play a role and this phenomenon could be present in the field and requires consideration, especially regarding the detection of virus in apparent “nulliparous” females and the identification of overwintering mechanisms and seasonally free vector zones
Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks
No full textThe distribution of Bluetongue virus (BTV) in Europe can be represented by two distinct and interconnected epidemiological systems (episystems), each characterized by different ecological characteristics and vector species. This study investigated the vector competence of Italian populations of Culicoides imicola and Culicoides obsoletus/scoticus to some representative BTV strains after artificial oral infection. The BTV strains were selected according to their ability to spread to one or both episystems and included BTV-4 ITA, responsible of the recent Italian and French BTV-4 outbreaks; the BTV-2 strain which caused the first BTV incursion in Italy, Corsica, and Balearic Islands; BTV-4 MOR, responsible for the epidemic in Morocco; and BTV-8, the strain which spread through Europe between 2006 and 2008. Blood-soaked cotton pledgets and Hemotek membrane feeder using Parafilm® membrane were used to artificially feed midges. For each population/strain, recovery rates (positive/tested heads) were evaluated using serogroup- and serotype-specific RT-PCR. The trial demonstrated that, except for the Abruzzo population of C. obsoletus/C. scoticus, which was refractory to BTV-4 MOR infection, all the investigated Culicoides populations are susceptible to the selected BTV strains and that, if prompt vaccination programs and restriction measures had not been implemented, BTV-2 and BTV-4 MOR could have spread all over Europe
Transmission Routes of Oropouche Virus: Potential Role of European Biting Midges and First Oral Infection Attempt in Wild-Caught Culicoides (Subgenus Avaritia)
No full textOropouche virus (OROV) is an emerging arbovirus primarily endemic to South America, capable of infecting humans, diverse animals, and multiple vector species. Although its ecology remains poorly understood, increased globalisation and human mobility raise concerns regarding potential introduction into Europe. To evaluate European risk, vector competence trials were conducted using Italian Culicoides obsoletus/scoticus and C. imicola, major vectors of livestock orbiviruses, orally exposed to a 2024 Cuban reassortant OROV strain. Of 260 surviving C. obsoletus/scoticus and 65 C. imicola midges, all samples tested negative for OROV RNA, suggesting limited vector competence. These findings indicate that tested European Culicoides populations are unlikely to support OROV transmission. Nevertheless, the virus’s broad host and vector range, reassortment potential, and presence of anthropophilic midges in Europe warrant continued surveillance and vector competence studies. Improved understanding of transmission dynamics, reservoir hosts, and potential vectors is critical for preparedness against Oropouche virus introduction and spread in non-endemic regions
Culicoides species responsible for the transmission of Epizootic Haemorrhagic Disease virus (EHDV) serotype 8 in Italy
No full textEpizootic haemorrhagic disease (EHD) is a viral disease transmitted by Culicoides biting midges that affects wild and domestic ruminants. The causative agent, EHD virus (EHDV), belongs to the family Sedoreoviridae, genus Orbivirus. The virus has never been reported in Europe until October 2022, when the virus was for the first time detected in Sicily and Sardinia. After the first clinical cases, an intensive entomological field activity was carried out in five EHD affected farms located in Sardinia, with the aim of assessing the EHDV vector competence in European species of Culicoides. EHDV‑8 was detected in C. imicola, C. obsoletus/scoticus, C. newsteadi, C. pulicaris ss, and C. bysta. The first 4 species have also been demonstrated to be able to transmit bluetongue virus (BTV). According to these results, it is likely that EHDV‑8, sharing the same transmission patterns of BTV, can also spread to Europe
Specie di zanzare presenti in Abruzzo e Molise e il loro possibile ruolo come vettori dei virus West Nile e Usutu
No full textIn 2019, entomological survey on mosquitoes was carried out in Abruzzo and Molise regions in central Italy to obtain data on local mosquito fauna. Collection sites were selected based on a previous ecoregion classification of the territory. From 2019 to 2021 virological surveillance for West Nile virus (WNV) and Usutu virus (USUV) on mosquitoes was carried out in the same regions, selecting ecoregions where virus circulation and vector presence were more likely, all mosquitoes were collected and identified, and the female mosquitoes were sorted in 3046 pools and tested for the presence of WNV and USUV by Real-time PCR. All pools tested negative for WND, while USUV was detected in 7 pools of Aedes caspius collected in Molise region, 17 pools of Culex pipiens s.l. (2 collected in Molise, 15 in Abruzzo), and 1 pool of Culiseta longiareolata collected in Molise. These results suggests the presence of an USUV enzootic cycle, maintained by Culex pipiens s.l. and Aedes caspius in both Italian regions, as well as providing a useful picture in terms of species presence and abundance for both regions. Ecoregions proved to be a very valuable tool in determining high risk areas for vector borne diseasesNel 2019, è stata effettuata una indagine entomologica sulle zanzare delle regioni Italiane dell'Abruzzo e del Molise per ottenere dati sulla composizione della fauna culicidica locale. I siti di cattura sono stati selezionati sulla base di una precedente classificazione in ecoregioni del territorio locale. Dal 2019 al 2021, in Abruzzo e Molise, è stata effettuata una sorveglianza virologica su zanzare per i virus West Nile e Usutu, selezionando le ecoregioni in cui la circolazione del virus e la presenza dei vettori fosse più probabile, tutte le zanzare catturate sono state identificate morfologicamente, e le zanzare femmine sono state divise in 3046 pool e testate, tramite Real-time PCR, per la presenza dei virus West Nile e Usutu. Tutti i pool sono risultati negativi per West Nile, mentre il virus Usutu è stato trovato in 7 pool di Aedes caspius catturate in Molise, 17 pool di Culex pipiens s.l. (2 provenienti dal Molise, 15 dall’Abruzzo), e in 1 pool di Culiseta longiareolata proveniente dal Molise. Questi risultati suggeriscono la presenza di un ciclo enzootico di USUV, mantenuto da Culex pipiens s.l. e da Aedes caspius in entrambe le regioni, oltre che dare un quadro sulla presenza e abbondanza delle specie di zanzare presenti nei territori di Abruzzo e Molise. La classificazione in ecoregioni si è dimostrata un valido strumento nella determinazione delle aree ad alto rischio per le malattie trasmesse da vettori
