Dengue

Mosquitoes spread Dengue, a viral fever. Most infections stay mild, but the disease can turn severe. Aedes aegypti, a tropical mosquito that also spreads Chikungunya, Zika and yellow fever, carries most of it.

A locally acquired case means a mosquito in Europe bit an infected person and then another person, so the whole cycle ran on the continent rather than on a trip abroad. By 30 September 2026 Italy had 59 local Dengue cases, in a season when mosquito-borne viruses spread further north in Europe than usual. France counted 124 local chikungunya cases over the same period.

Dengue's main carrier also turned up further north in 2026. A member of the public in east London reported Aedes aegypti in August through the Mosquito Watch scheme run by the UK Health Security Agency, which confirmed the species was breeding there. UKHSA is treating the site with larvicide and aims to eradicate the colony. Whether Britain's present climate would let the Dengue mosquito settle for good remains an open question for ECDC.