Expert comment: Chikungunya transmission risk in Switzerland

20.02.2026

A study published this week found that chikungunya virus can be transmitted by the Asian tiger mosquito at temperatures as low as 13-14°C – lower than previously estimated, which puts Europe, including Switzerland, at risk for longer periods of the year. Pie Müller, medical entomologist and Head of Vector Biology at Swiss TPH, comments.

Tiger mosquito (Photo: Swiss TPH/AdobeStock)

"These findings underline that the risk for chikungunya transmission exists across large parts of Central Europe, including Switzerland, and potentially over several months during the mosquito season. In Switzerland, the Asian tiger mosquito first became established in the Canton of Ticino about 20 years ago and has since spread to other regions, particularly around Basel and Geneva. Last year, a locally acquired case transmitted through Asian tiger mosquitoes was reported near Strasbourg, around 100 km from Basel. This case highlights that local transmission of chikungunya transmission could also become a reality in Switzerland.

With climate change extending the warm season, the conditions for transmission are becoming more favourable. In southern Europe, scientists are now observing year-round activity of the Asian tiger mosquito, meaning the cold seasons naturally braking transmissions become shorter.

Swiss TPH, on behalf of the Swiss federal government and cantons and in collaboration with other partners, has been conducting mosquito surveillance across Switzerland for years. What we are currently seeing in Switzerland reflects this shift. Mosquito populations are increasing in number and expanding in geographic range. However, mosquitoes remain inactive during the winter months. Since we first detected the Asian tiger mosquito in Basel in 2015, its range has steadily expanded and now extends across the whole city and surrounding areas. Rising temperatures, particularly in recent years, are likely to have accelerated this spread.

The Asian tiger mosquito is now established in Switzerland, meaning that the conditions for local transmission of chikungunya exist, even though no cases have yet been documented here. That is exactly why sustained monitoring is essential: it allows targeted mosquito control measures to be implemented, helping to reduce the risk of chikungunya infections."

Original study: Sandeep Tegar, Dominic P. Brass, Bethan V. Purse, et al. Temperature-sensitive incubation, transmissibility and risk of Aedes albopictus-borne chikungunya virus in Europe. J R Soc Interface. 2026. doi: 10.1098/rsif.2025.0707

Contact for media requests: communications@swisstph.ch