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].
At present, environmental conditions in most EU/EEA areas where Ae. albopictus or Ae. aegypti are established are unfavourable for mosquito activity and virus replication in mosquitoes. Therefore, locally acquired chikungunya virus disease cases are unlikely 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