Key Points

Chikungunya, Dengue, and Zika

• Since May 1, 2026, 100 imported cases of dengue, 25 imported cases of chikungunya, and 1 imported case of Zika have been identified and investigated in the Île-de-France region (compared to 189 imported cases of dengue and 173 imported cases of chikungunya during the same period in 2025).
• In the Île-de-France region, the first outbreak of local transmission of chikungunya was identified in Nogent-sur-Marne in the Val-de-Marne department (94), with 5 cases identified to date. The onset dates of symptoms for these five cases range from August 16 to 27.

West Nile Virus Infections

• As of September 6, 206, 12 locally acquired human cases of West Nile virus (WNV) infection have been identified in Île-de-France.

Asthma

• The summer vacation period corresponds to the time when the risk of asthma exacerbation is lowest. Maintenance treatment for asthma patients is sometimes discontinued during the summer at the initiative of the doctor or the family, with instructions given to parents to resume it before school starts. It is important to resume maintenance treatment at least 8 days before school starts to ensure an asthma-free start to the school year.