West Nile, Korean mosquito exonerated: virus travels on indigenous people

What is behind the increase in West Nile cases observed this year in some areas of Italy, such as Padua and Veneto? The surveillance eyes are always focused on the mosquitoes on which the virus travels, for fear that new vectors may arrive. It will be like this? At the moment the Korean mosquito is exonerated (until proven otherwise). Feared for its ability to withstand the cold, they had spotted it for the first time in 2011 in the province of Belluno, then they also intercepted it elsewhere, for example in Trentino, and it is not new even in neighboring Switzerland. At the end of 2021 a team of scientists from the State University of Milan collected abundant evidence of its presence in Lombardy, where it seems to be rapidly taking up residence in particular in the foothills of the province of Bergamo (so much so that among the hypotheses it was thought that there was arrived by plane ‘via Orio al Serio’). But this time she is not the ‘defendant’ in the West Nile case. “In Italy – explains to Adnkronos Salute Sergio Zanzani, researcher at the University of Milan, expert in veterinary parasitology of the Department of Veterinary Medicine and Animal Sciences – it is given enough to confirm that the transmission of West Nile occurs thanks to an autochthonous vector, the mosquito that has always existed in Italy and that bites man: the ‘Culex pipiens’, a complex of species. It is the mosquito that we have always had, before the arrival of tiger mosquitoes, and that bites in the evening and at night “. While as regards the Korean, “for now, the field data of those who have seen Aedes koreicus in West Nile areas seem to attribute little significance to this new species. The evidence of circulation of West Nile virus in areas where there is the koreicus doesn’t seem to support a large vector capability of it, “he says. And then the cold-friendly mosquito, on which a lighthouse has been lit for a while, would also have an ‘alibi’. The Korean buzzing insect “has been gradually expanding in our country but its seems more like a spread at the pre-alpine level, from a mosquito that comes from colder climates and has adapted – argues Zanzani – Instead, the location of the West Nile case study is also this year in the Lower Po Valley “. In other words, the Korean would be stationed elsewhere. They are the native ‘colleagues’ who continue to “transmit West Nile on Italian territory”, this year more. “Culex pipiens are a competent vector, so there is nothing new on this front. Aedes albopictus, the real name of the tiger mosquito,” which has permanently and extensively colonized Italy, “seems not to be a good vector capable of transmitting this virus. And even the most recent observations do not seem to have anything to do with West Nile “. These new mosquitoes, continues the expert, “mainly concerned the North-East: Aedes koreicus, which came to settle first in the province of Genoa, now covers the Canton of Ticino, the province of Como, the province of Sondrio as arc. year it reached the province of Bergamo and joined with the province of Trento and the provinces of Triveneto. But the distribution of the Korean mosquito with that of the West Nile does not fit very well. So you have to look at the native mosquito. After all – he smiles. – mosquitoes are a typical product in the Po Valley “.