More than 1,000 new cases of chikungunya have been recorded in one month in Reunion. Faced with this rapid spread, the Regional Health Agency (ARS) is increasing mosquito control operations to slow the epidemic, which has already affected 19 of the island's 24 municipalities.
Near the city center of Le Tampon, one of the most affected areas in the south of the island, Yolant Galibert goes door-to-door to raise awareness among residents and identify potential sources of contamination.
"Do you know that chikungunya is circulating?" he asks Martine Thienlock Sen, before listing the symptoms: fever, joint pain, aches and pains, even red patches on the body.
Receptive, she allows health workers to inspect her garden. "It's a preventative measure, it's essential," she tells AFP. Quickly, a tire hidden in a thicket filled with stagnant water, conducive to the proliferation of mosquitoes, is spotted.
"We'll come back to get rid of mosquitoes," the agent assures. In a suit and panoramic mask, he returns a few minutes later, sprayer in hand.
Since August 2024, 1,069 cases of this disease, transmitted by the tiger mosquito, have been recorded on the island of nearly 900,000 inhabitants, a French department in the Indian Ocean.
In total, 19 of the 24 municipalities in the territory are affected, particularly in the south of Reunion. Although the health impact remains limited with eight visits to the emergency room and seven hospitalizations, according to the prefecture, the authorities are calling for vigilance.
"The more cases we have, the greater the risk of serious forms will be," warns Nicolas Odon. Especially since the southern summer and recent rains are promoting the spread of arboviruses, such as dengue fever and chikungunya.
– Sterile males and biocide –
Until this recent outbreak, no cases had been reported in Reunion since 2010. "It is likely that a resident or a tourist brought the disease, since a mosquito itself became the contaminant," analyses Nicolas Odon.
The tiger mosquito was the cause of the major chikungunya epidemic which, between 2005 and 2006, affected 260,000 people on the island, 225 of them fatally.
"Some patients could not even be reached: they had very severe joint pain. And the health establishments were saturated," recalls Xavier Deparis, director of health monitoring at the ARS.
Xavier Deparis believes that the 2025 epidemic should be "of lesser magnitude than 20 years ago", particularly because it is currently concentrated in the west and south of the island, but he remains "vigilant".
This time, the authorities are also relying on an experiment to counter the epidemic.
Starting in April, 10 million sterile tiger mosquitoes will be released in the south of the island, particularly in Saint-Joseph.
These irradiated males will be covered with a biocide that they will transmit to the females and larval habitats, thus blocking the hatching of the eggs. "The goal is to reduce the population of 90%," explains Jérémy Bouyer, a researcher and specialist in genetic control at the Center for International Cooperation in Agricultural Research for Development.
Mosquitoes remain the deadliest animals in the world, responsible for around 800,000 deaths per year, recalls the Institute of Research for Development.
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