medecinedesvoyages.net
Patrick GEROME, 02/21/2026
A study published in the Journal of the Royal Society Interface found that chikungunya virus CHIKV) can be transmitted by Aedes albopictus at temperatures as low as 13-14°Cwhich is 2.5°C lower than previous estimates (16-18°C), extending the potential transmission season across Europe.
Figure : Number of months per year with a risk of transmission
The transmission is now possible pendant more than six months per year in Spain, Portugal, Italy and Greece, three to five months in Belgium, France, Germany and Switzerland, and for two months in the south-east of England, in July and August.
The revised temperature threshold fundamentally changes the chikungunya risk landscape in Europe, as transmission can now occur during cooler months, a time when mosquito activity was previously deemed insufficient to enable viral replication. This period of expanded transmission increases the cumulative number of infectious mosquito days per season, amplifying epidemic potential within established vector populations and allowing circulation of the virus in regions previously considered marginal for transmission.
The earlier start of transmission, in late May/early June, compared to the usual July-August peaks, suggests that spring warming creates favorable conditions for earlier seasonal amplification.
Global warming in Europe, approximately twice as fast as the global average, combined with the northward expansion of Aedes albopictus, is creating conditions for continued mosquito activity throughout the year in Southern Europe. This removes the traditional winter brake that previously interrupted transmission cycles between seasons, potentially favoring the establishment of an endemic population rather than annual reintroduction through imported cases.
Future developments will depend heavily on the ability of Aedes albopictus to establish permanent populations in currently marginal areas, particularly in the UK and Northern Europe. Warning signs of a worsening situation include: the detection of populations of mosquitoes wintering in Southern Europe, allowing continued transmission; the establishment of Aedes albopictus in the south-east of England, creating a risk of local transmission; an earlier start of seasonal transmission (before June); and an increase in the size of outbreaks, suggesting sustained human-to-human transmission chains rather than isolated transmissions from imported cases. Climate projections indicate a continued northward expansion of mosquito-friendly habitats, with the lower transmission threshold (13-14°C) allowing viral circulation in regions previously considered too cold. The expansion of the vector’s range, the lengthening of transmission seasons, and the potential disappearance of the winter firebreak in Southern Europe create conditions conducive to the transition of chikungunya from an imported disease with occasional local outbreaks, to an endemic pathogen with seasonal epidemic cycles similar to those observed for dengue in tropical regions.
Source : BeaconBio
