Tiger mosquito reaches 40 municipalities in Portugal

The Directorate-General of Health (DGS), however, stresses that the fact that the insect is detected does not imply that pathogens are present or that the viruses are actively circulating in the community; the number of cases locally transmitted in the country is still zero.

The data provided by the DGS and the Vector Surveillance Network (REVIVE) show that all 18 dengue cases and the four chikungunya cases confirmed in the country since the start of 2026 are imported cases that were picked up abroad. Moreover, examinations of mosquito samples collected in the field—including the more recent findings in the municipalities of Braga and Amares after complaints from the public—have revealed no presence of the viruses.

On this basis, the DGS has rated the 40 affected municipalities as "Level 1" risk (yellow alert), requiring enhanced monitoring and the removal of breeding sites, without it being necessary to activate "Orange" (high risk) or "Red" (outbreak) alert levels.

Climate change

Climate change and higher temperatures enable this species to become established, a pattern which has also been seen in other countries in Europe.

In order to lower the chance of local outbreaks resulting from imported cases, the authorities tell people to get rid of containers with standing water—for example, saucers from plant pots, buckets or gutters—use insect repellent, and report any possible sightings through websites such as MosquitoWeb and Mosquito Alert.