Key Points

• Initially limited to departments where the presence of Aedes albopictus had been confirmed, the enhanced surveillance program was expanded in 2020 to all metropolitan departments.

• During the 2021 season, 47 imported cases of dengue were reported, mostly from Réunion, as well as one case of chikungunya imported from Brazil.

• One locally acquired case of dengue (likely transmitted via a transplant) was identified during the 2021 season.

• No secondary local transmission was identified in the region during the season.

• The estimated number of viremic cases present for at least one day in Île-de-France was 38 (79% of known cases).

• 109 entomological surveys and 2 adulticide treatments were conducted in 2021.

• In 2021, 17 new municipalities were identified as colonized in the Île-de-France region, bringing the total number of colonized municipalities to 54. All departments in the Île-de-France region now had colonized municipalities.