Indian Ocean Chikungunya Outbreak Exceeds 47,000 Cases

Since August 2024, widespread outbreaks of the chikungunya virus disease have been reported in the western Indian Ocean.

As of May 12, 2025, France's Departments of La Réunion and Mayotte have been significantly impacted.

The World Health Organization (WHO) Disease Outbreak News (567) today wrote, 'Although chikungunya outbreaks and endemic transmission occur annually in several countries and territories around the world, the Indian Ocean islands have not experienced major outbreaks for nearly two decades.'

In La Réunion, over 47,500 cases and twelve associated deaths have been reported as of May 4, 2025, with sustained high transmission across the island.

In Mayotte, the first locally transmitted cases since 2005–2006 have been detected, raising concern about similar large outbreaks. As of early May 2025, about 90 cases had been confirmed.

France's public health response measures, including enhanced surveillance, vector control activities, and novel targeted vaccination efforts, have been implemented to contain the outbreaks.

However, further outbreak activity in the islands of the Indian Ocean can be expected, says the WHO.

Seperately, the U.S. CDC issued a Level 2 - Practice Enhanced Precautions travel advisory that says, 'If you are pregnant, reconsider travel to the affected areas, particularly if you are close to delivering your baby. Mothers infected around the time of delivery can pass the virus to their baby before or during delivery.'

According to the CDC, vaccination is recommended for travelers visiting an area with a chikungunya outbreak, such as these French departments in the Indian Ocean.

Chikungunya vaccines are approved for use in the United States and are commercially available at travel clinics and pharmacies.