A major outbreak of chikungunya virus has struck La Réunion, with over 47,500 confirmed cases and 12 related deaths as of 4 May, 2025.
The island, a French territory in the Indian Ocean, had not seen an outbreak of this scale since 2005-2006.
In Mayotte, another French territory nearby, locally transmitted cases have also reappeared for the first time in nearly two decades.
The chikungunya virus is spread by infected Aedes mosquitoes and causes symptoms such as fever, joint pain, headache, rash, and fatigue.
Although the illness is usually mild and self-limiting, it can cause severe complications in newborns, elderly people, and those with health issues like diabetes or heart disease.
Since the outbreak began in August 2024, La Réunion has seen a sharp rise in cases, especially since early 2025. By March, weekly confirmed cases jumped from just 30 to over 4,000.
Read Also: WHO warns of Marburg virus outbreak in Tanzania, eight dead
More than 170,000 people have visited health centers with suspected symptoms, with the southern areas, including Le Tampon, being the hardest hit.
While most patients recover within a week, 340 people have been hospitalized, mainly older adults and babies under six months.
So far, 66 cases have been classified as severe, involving organ failure, and 12 deaths have been confirmed as linked to the virus. Twenty-eight other deaths, including one in a newborn, are still under investigation.
In response, La Réunion’s health authorities activated an emergency response plan, ramping up mosquito control, hospital readiness, and vaccination for high-risk adults under age 65.
Hospitals have increased bed space and set up special triage systems to handle the surge in patients.
Mayotte has also confirmed 116 cases, including 57 locally transmitted ones. It is the first local transmission there since the 2005–2006 outbreak.
Authorities have taken action by intensifying mosquito control, improving hospital labs, and running public awareness campaigns to prevent further spread.
The World Health Organization (WHO) is closely monitoring the outbreak. It is helping affected areas improve laboratory testing, healthcare services, and mosquito control.
WHO has also conducted training for health workers and provided technical advice to local governments.
Experts warn that chikungunya can spread quickly in populations with no prior exposure, as seen in La Réunion and Mayotte.
The high number of mosquitoes and lack of community immunity make these areas vulnerable to continued outbreaks.
People are advised to protect themselves by wearing long-sleeved clothing, using mosquito repellents, and avoiding mosquito-infested areas, especially during the day when Aedes mosquitoes are most active.
WHO says no travel restrictions are needed at this time but urges countries in the region to stay alert.
