Key Points

• From January 1 to December 31, 2025, 185 cases of leptospirosis were confirmed in Mayotte (171 by PCR and 14 by serology), representing an annual incidence rate of 56 cases per 100,000 inhabitants

• The 2025 epidemic peak occurred late, in week 19, with cases circulating from February through the end of May. The passage of Cyclone Chido and Tropical Storm Dikeledi may have influenced the dynamics of the epidemic

• Since the beginning of 2026, 57 cases of leptospirosis have already been recorded, including 8 hospitalizations, one of which was admitted to the intensive care unit.

• Rainfall observed since the beginning of 2026, although slightly lower than in 2025 during the same period, could promote the persistence of leptospires in the environment and increase the risk of transmission in the coming weeks.

• A typical seasonal lag of 1 to 3 months between the onset of rains and the appearance of the first cases suggests a possible increase in incidence by April, the period when the epidemic peak is generally observed

• Adherence to personal protective measures during high-risk activities, as well as improvements in sanitation and waste management, remain essential to limit the transmission of leptospirosis in Mayotte