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Cazzin S, Liechti N, Jandrasits D, Flacio E, Beuret C, Engler O, Guidi V. First Detection of West Nile Virus Lineage 2 in Mosquitoes in Switzerland, 2022. Pathogens 2023; 12:1424. [PMID: 38133307 PMCID: PMC10748287 DOI: 10.3390/pathogens12121424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
West Nile virus (WNV) is one of the most widespread flaviviruses in the world, and in recent years, it has been frequently present in many Mediterranean and Eastern European countries. A combination of different conditions, such as a favourable climate and higher seasonal average temperatures, probably allowed its introduction and spread to new territories. In Switzerland, autochthonous cases of WNV have never been reported, and the virus was not detected in mosquito vectors until 2022, despite an entomological surveillance in place in Canton Ticino, southern Switzerland, since 2010. In 2022, 12 sites were monitored from July to October, using BOX gravid mosquito traps coupled with honey-baited FTA cards. For the first time, we could detect the presence of WNV in FTA cards and mosquitoes in 8 out of the 12 sampling sites monitored, indicating an unexpectedly widespread circulation of the virus throughout the territory. Positive findings were recorded from the beginning of August until mid-October 2022, and whole genome sequencing analysis identified a lineage 2 virus closely related to strains circulating in Northern Italy. The entomological surveillance has proved useful in identifying viral circulation in advance of possible cases of WNV infection in humans or horses.
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Affiliation(s)
- Stefania Cazzin
- Institute of Microbiology, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), 6850 Mendrisio, Switzerland; (D.J.); (E.F.); (V.G.)
| | - Nicole Liechti
- Spiez Laboratory, Federal Office for Civil Protection, Austrasse, 3700 Spiez, Switzerland; (N.L.); (C.B.); (O.E.)
| | - Damian Jandrasits
- Institute of Microbiology, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), 6850 Mendrisio, Switzerland; (D.J.); (E.F.); (V.G.)
- Spiez Laboratory, Federal Office for Civil Protection, Austrasse, 3700 Spiez, Switzerland; (N.L.); (C.B.); (O.E.)
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Eleonora Flacio
- Institute of Microbiology, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), 6850 Mendrisio, Switzerland; (D.J.); (E.F.); (V.G.)
| | - Christian Beuret
- Spiez Laboratory, Federal Office for Civil Protection, Austrasse, 3700 Spiez, Switzerland; (N.L.); (C.B.); (O.E.)
| | - Olivier Engler
- Spiez Laboratory, Federal Office for Civil Protection, Austrasse, 3700 Spiez, Switzerland; (N.L.); (C.B.); (O.E.)
| | - Valeria Guidi
- Institute of Microbiology, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), 6850 Mendrisio, Switzerland; (D.J.); (E.F.); (V.G.)
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