Chikungunya virus disease risk assessment for mainland EU/EEA
Chikungunya virus disease is an Aedes-borne disease widely distributed in tropical and subtropical regions. Globally, the virus is predominantly transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Aedes albopictus is established in a large part of Europe. Aedes aegypti is established notably in Cyprus, around the Black Sea, and in the outermost region (OR) of Madeira.
Chikungunya is not endemic in mainland EU/EEA and most reported cases are associated with travel outside of the region. When environmental conditions are favourable, viraemic travel-related cases can trigger local transmission in areas where Ae. albopictus is present. This has been demonstrated by several chikungunya outbreaks in mainland EU/EEA since 2007. According to scientific literature, ambient temperature is one of the most important environmental factors influencing mosquito-borne transmission of chikungunya virus. The optimal daily average temperature for chikungunya virus transmission by Ae. albopictus in temperate zones of the northern hemisphere is 24 – 26 °C, although transmission might occur within the temperature range of 12 – 30 °C [1].
The environmental conditions in most areas of the EU/EEA where Ae. albopictus or Ae. aegypti are established are becoming favourable for mosquito activity and virus replication in mosquitoes; therefore, locally acquired chikungunya virus disease cases might occur in the coming weeks.
In 2025, the first locally acquired chikungunya virus disease cases in mainland EU/EEA were reported earlier than usual in the season with symptom onset in late May/early June. This was most likely due to a high number of imported cases - particularly from EU outermost regions – combined with favourable environmental conditions for mosquito activity and viral transmission.
References:
- Gizaw Z, Salubi E, Pietroniro A, Schuster-Wallace CJ. Impacts of climate change on water-related mosquito-borne diseases in temperate regions: A systematic review of literature and meta-analysis. Acta Trop. 2024 Oct;258:107324. Available at: https://www.ncbi.nlm.nih.gov/pubmed/39009235