European experts sound alarm while mosquito-borne and tick-borne diseases will develop in a warmer climate

A new study presented this year at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Amsterdam, the Netherlands (April 13-16), shows that the range of vector-borne diseases such as chikungunya, dengue, Leishmaniasis and Ticks Encephalitis (TBE) is expanding.

Under the impetus of climate change, international travel and trade, the epidemics of vector-borne diseases will increase in much of Europe over the next decades, and not just in the temperate countries of Europe. the Mediterranean. Even previously unaffected areas at higher latitudes and altitudes, including parts of northern Europe, could experience an increase in epidemics unless steps are taken to improve surveillance and data sharing, and to monitor the environmental and climatic precursors of epidemics, along with other preventive measures.

"Climate change is not the only or even the main factor behind the rise of vector-borne diseases in Europe, but it is one of many factors to globalization, socio-economic development, urbanization and widespread land-use change, limiting the import and spread of these diseases, "says Professor Jan Semenza of the Center European Commission for Disease Prevention and Control, Stockholm, Sweden.

"The harsh reality is that longer warm seasons will widen the seasonal window for the potential spread of vector-borne diseases and will promote larger epidemics," said Dr. Giovanni Rezza, director of the department's infectious diseases department. Istituto Superiore di Sanitá of Rome. , Italy. "We must be prepared to deal with these tropical infections." Lessons learned from recent outbreaks of West Nile virus in North America and chikungunya in the Caribbean and Italy underscore the importance of badessing future outbreaks. risks of vector-borne diseases and to prepare for unforeseen events for future epidemics. "

However, the authors emphasize that, given the complex interaction between several factors (for example, temperature warming and international travel), weather-sensitive pathogens and adaptation to climate change, it is difficult to predict the future burden of disease.

Global warming has allowed mosquitoes, ticks and other disease-causing insects to proliferate, adapt to different seasons and invade new territories in Europe over the past decade – accompanied by dengue foci in France and Croatia, malaria in Greece, South-East Europe and the chikungunya virus in Italy and France.

The authors say that what is disturbing is perhaps only the visible part of the iceberg. "The Mediterranean Europe is now a part-time tropical region, where competent vectors like the tiger mosquito are already established," said Dr. Rezza.

A warmer and wetter weather could provide ideal conditions for the Asian tiger mosquito (Aedes albopictus), which spreads viruses to the origin of dengue and chikungunya, so that it can reproduce and spread in large parts of Europe, especially the south and east of the United Kingdom and central Europe.

Previously, dengue transmission was largely confined to the tropics and subtropics because freezing temperatures kill mosquito larvae and eggs, but longer seasons could allow an albopictus to survive and spread for the most part. from Europe in a few decades, the researchers said.

The European climate is already conducive to the transmission of Lyme borreliosis and tick-borne encephalitis transmitted by ticks (mainly Ixodes ricinus), with about 65 000 cases of Lyme borreliosis per year in the Union. European Union and a 400% increase in reported cases. EBT cases in European endemic areas over the past 30 years (partly because of enhanced surveillance and diagnosis).

In the future, warmer winter temperatures, longer growing seasons, and warmer summers sooner could make conditions more tick-friendly and broaden the range of host deer populations, they said. authors. Climate change models indicate that by 2040-2060, the habitat of Ixodes ricinus could grow by 3.8% in Europe, with Scandinavia being the most at risk.

In addition, improving weather conditions for sandflies – the main vector of leishmaniasis – could extend their geographical reach to the south of the UK, to France and to Germany by the end of the year. from the 2060s.

"Given the continuing spread of invasive mosquitoes and other vectors in Europe, we need to anticipate outbreaks and respond quickly," said Professor Semenza. "Public health agencies need to improve surveillance, for example through early warning systems, to increase awareness among health care workers and the general public of potential risks, and to adopt innovative control strategies such as interventions. community. "

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European Society of Clinical Microbiology and Infectious Diseases