Malaria, dengue fever, chikungunya… Diseases which, from Europe, seem distant. And for good reason: these so-called vector-borne infectious diseases, that is to say transmitted to humans by a vector (mosquitoes, ticks, etc.), have long been present only in tropical latitudes. According to the WHO, the World Health Organization, these diseases cause each year more than 700,000 deathsof which more than 600,000 are due to malaria alone. And in recent years, the number of cases of these tropical diseases in northern countries has been increasing. The main culprit: climate change.
The increasing frequency of milder winters and warmer summers allows many tropical species to move north. This is particularly the case of the tiger mosquito, whose bite can transmit viruses such as Zika, chikungunya and dengue. Arriving in France in 2004, this insect was present, on January 1, 2024, in 78 metropolitan departments according to the Ministry of Health.
Nearly 20% of dengue cases “attributable to climate change”
And the progression of the tiger mosquito continue towards the Northlike in Belgium. “In two places in particular we found small populations that had survived the winter of 2022-2023, and they were still there at the end of last year. They must still be there today. We think it is settling in,” explains Isra Deblauwe, an entomologist at the Institute of Tropical Medicine in Antwerp, to RTBF.
According to science journalist Claire Ainsworth, in an article published in the journal Nature, “in 2022, 71 cases of locally acquired dengue fever were recorded in continental Europe, equivalent to the total number of cases recorded between 2010 and 2021”. And according to a study carried out by researchers at Stanford University, in the United States, on average, almost 20% of dengue cases in the world “are attributable to global warming”.
A risk of “viral spillover” from the Arctic
Other viruses, such as West Nile (WNV), are also making their way back to Europe. A study, published in the journal Nature Communications, demonstrated that the establishment of this virus transmitted by common mosquitoes was due, at least in part, to climate change. “Our results demonstrate a notable increase in ecologically suitable area to the circulation of the WNV during the period 1901-2019, while this area remains largely unchanged in a counterfactual without climate change”, summarize the researchers.
Even more worrying: according to a study carried out by Canadian researchers, global warming could cause a “viral spillover” from the Arctic. In other words, the melting of the ice could release viruses preserved in icesometimes for tens of thousands of years. The possibility of an overflow is “completely unpredictable, and its consequences too, ranging from a benign nature to a real pandemic” Audrée Lemieux, first author of the study, told AFP. Even if, according to her, “the probability of dramatic events remains very low”.
To face these new threats, researchers organize themselves. The Pasteur Institute plans in particular the creation of a Center for vector-borne diseases which “will bring together all its teams of experts in microbes, their hosts and vectors” and which “will participate in bringing the teams together in order to anticipate future epidemics and to reduce and control risks.
