The premature arrival of mosquitoes and fears about Dengue.The parasitologist:«Citizens must be careful of stagnant water»

Alessandra Della Torre, professor at Sapienza University:«With climate change the life cycle of larvae is shortened»

Once upon a time there were mosquitoes in the summer.Today, thanks to climate change, they are there almost all year round.The European Copernicus program has certified that February 2024 was the ninth consecutive warmest month ever, with 1.77 degrees higher than the average of the pre-industrial period (1850-1900) and with "exceptionally high" daily temperatures in the first half of the month.This situation has also had repercussions on the life cycles and reproduction of some insects, including mosquitoes, which have already made their first appearance of the year in some areas of Italy a few weeks ago.«We are about to publish a study in which we compared data on the tiger mosquito population in 2012 and 2023.The difference is abysmal, especially in the last months of the season", explains Alessandra Della Torre, professor of parasitology at the Sapienza University of Rome.«In 2023 – specifies the expert – we had high densities in tiger mosquito populations until November, while in 2012 the season ended significantly earlier».

The two most widespread species in Italy

In Italy there are mainly two species of mosquitoes.The first is the so-called "nocturnal mosquito", a native insect that makes its appearance especially after sunset and is often found inside the home.It is she who transmits the virus West Nile, contracted by birds but transferable to humans through mosquito bites.The second most widespread species in Italy is the tiger mosquito, which is actually an invasive species that arrived in Europe in the 1990s.«This mosquito transmits viruses not normally present in Italy, such as Zika and Dengue.For there to be a risk of transmission – explains Della Torre – someone needs to contract the virus in endemic areas.At that point the tiger mosquito, which is a competent vector, transmits the virus from an infected person to others it bites."

The role of climate change

If the mosquito season has visibly lengthened in recent years, climate change is to blame.«The higher the temperatures, the shorter the life cycle of the larvae and, consequently, the mosquito population increases exponentially», explains the professor from Sapienza University of Rome.The other climatic factor that affects the presence of mosquitoes is rainfall.The presence of water is in fact fundamental for the spread of these insects, which struggle to reproduce in arid and drought environments.The increase in temperatures due to climate change will lead to a further lengthening of the mosquito season.To the point that an international network of universities has created Mosquito Alert, an application that allows citizens to report the presence of mosquitoes at different times of the year with some photographs.«This project, in which we at Sapienza are also participating, is fundamental for collecting data at a national level.Especially in these months of the year, because it can help us measure the start of the season in the different areas of Italy", explains Alessandra Della Torre.

Fears for Dengue

There is another reason that this year contributes to making the start of the mosquito season even more fearful and it has to do with theDengue emergency, a tropical infectious disease that is spreading at alarming rates in some areas of the world.«In South America we are witnessing a frightening circulation, with a number of cases 400 times higher than last year», recalls the Sapienza professor.The problem is that the more the disease circulates in one region of the world, the more likely it is for it to arrive elsewhere.For it to arrive in Italy, it is sufficient for someone to contract the disease while in one of the endemic areas.At that point, once you return home, the virus can be transmitted by the tiger mosquito.«This year the possibility of an infected person arriving from a tropical endemic area is much higher due to the ongoing epidemics.This makes it more likely that cases of autochthonous transmission will be triggered if one of these people is bitten by the tiger mosquito", warns Della Torre.

The government's strategy

In response to growing concerns around the world about the spread of Dengue fever, in recent days the government has drastically increased checks on planes and ships arriving in Italy, particularly from countries considered at risk.Each plane or vessel is asked to notify the list of the last ten ports touched, or those passed through in the previous 28 days.Added to this is the request addressed to the crews to sanitize the "sensitive" areas, such as the holds and passenger cabins, and ensure the absence of water stagnation.For the rest, mosquito disinfestation activities proceed with the routine operations of the various municipal administrations.«What is prescribed at a national level is control against larvae, especially in manholes, which generally begins in April», explains Della Torre.While insecticidal products against already adult insects "are recommended only in the event of an epidemic, because they have a large environmental impact".

How to defend yourself

As far as citizens are concerned, the roads available to protect themselves from mosquitoes are always the same.The most important thing to pay attention to, explains Della Torre, is to avoid water stagnation, for example by frequently changing the water in the pet bowls and periodically emptying the children's pools.Outside the home you can use repellents, but they don't always work and they quickly dilute with sweat.At home, however, the best solution remains mosquito nets, to the happiness of companies in the sector.«The Italians are taking action.Requests, compared to the same period last year, stand at +15%", rejoices Marco Marcantoni, CEO of Sharknet, a Roman company that exports mosquito nets all over the world.Orders are increasing not only from private citizens but also from many hoteliers, who - adds Marcantoni - "are waiting for the arrival of tourists for Easter and don't want to be caught unprepared".

Cover photo:EPA/Andre Borges