Key Points

• In the Grand Est region, 45 imported cases of chikungunya, 34 imported cases of dengue, and 2 imported cases of Zika virus infection were identified between May 1 and September 9, 2025.

• A first outbreak of locally transmitted chikungunya, involving a single case, was identified in late June in the Bas-Rhin department.

• More recently, in mid-August 2025, a second outbreak of locally transmitted chikungunya occurred, also in the Bas-Rhin department.