Leptospirosis outbreak in La Réunion driven by winter‑resistant strain

A new strain of leptospirosis that can survive the austral winter has been identified on the French overseas department of La Réunion by researchers at the Centre national de recherche scientifique (CNRS). Between 1 January and 16 July 2026, the regional health agency (ARS) recorded 217 indigenous cases, a sharp rise from the usual 80–100 cases per year. Of these, 120 patients (65%) were hospitalised, one death has been confirmed and a second possible death is under investigation.

Scientists suspect the strain may spread more easily because of climate change and are examining whether infection rates in local rat populations have increased, potentially creating more favourable conditions for transmission.