Mosquitoes aren't just triggered by heat: a combination of factors can also trigger them.
Does hotter weather equal more mosquito-related diseases? This isn't necessarily the case, because "the activity of these insects is influenced by several factors. We often make the mistake of simplifying and linearly linking causes with what we consider effects tout court, but which actually have a more complex dynamic. And this is the case with extreme heat, which we link to the presence of mosquitoes. But this isn't the case, as demonstrated by this season in which we see fewer cases of some infections caused by mosquito bites." Epidemiologist Gianni Rezza, associate professor of Hygiene at the Vita-Salute San Raffaele University in Milan, explains this to Adnkronos Salute. Milano.
In addition to the heat, "there are several factors to consider. For example, humidity and rainfall. This year," the expert emphasizes, "there has been little rainfall. We've been haunted by strong, continuous sunshine. And this has certainly played a role. One thing is certain: the mosquito breeding cycle has been brought forward, but this hasn't meant increased activity compared to last year. On the contrary. If we consider West Nile virus, for example, last year we had a huge number of cases, while this year we have a third of the cases of 2025, at least so far. And the trend could change due to dynamics independent of simple temperature."
For example, in avifauna (birds), the main natural reservoir of West Nile virus, climatic conditions and low rainfall "may have partly determined these differences," Rezza muses. "This means there's a complexity to these dynamics that's not easy to understand: there's no equation that hotter means more mosquito-borne diseases. The mix of causes that determines the epidemiology of arboviruses is difficult to predict. But in any case, it's necessary to monitor, have data to analyze, and take preventive action against all known factors," the epidemiologist concludes.
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(Adnkronos)
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