Key Points

Chikungunya, Dengue, and Zika

• Since May 1, 2026, 106 imported cases of dengue, 28 imported cases of chikungunya, and 1 imported case of Zika have been identified and investigated in Île-de-France (compared to 194 imported cases of dengue and 176 imported cases of chikungunya during the same period in 2025).
• In the Île-de-France region, the first cluster of locally transmitted chikungunya was identified in Nogent-sur-Marne in the Val-de-Marne department (94), with 6 cases identified to date. The onset dates of symptoms for these five cases ranged from August 16 to August 29.

West Nile Virus Infections

• As of September 14, 206, 17 locally transmitted human cases of West Nile virus (WNV) infection have been identified in Île-de-France.
• WNV was first detected in the region in May 2026 in mosquito excreta collected from a trap set up in department 94. Since June 2026, the National Reference Laboratory for West Nile Virus (ANSES) has detected 7 avian cases positive for WNV in 5 departments of Île-de-France (75, 77, 92, 94, and 95). Six equine cases have been confirmed as positive in departments 77, 91, and 95.

COVID-19

• Emergency room visits: The number of emergency room visits for suspected COVID-19 continued to rise in Week 36. This increase was observed among children under 15 and people aged 15–64. However, the numbers remained lower than those observed during the same period in 2025 or 2024.
• SOS Médecins: The number of procedures for suspected COVID-19 continued to rise in Week 36. This increase was particularly evident among people aged 15–64. Case numbers were approaching those observed during the same period in 2025 and remained low compared to 2024.
• SARS-CoV-2 in wastewater: Data on SARS-CoV-2 circulation in wastewater are not available for Week 37.