World Health Organization raises concern about spread of mosquito-borne Chikungunya virus

The World Health Organization issued an urgent call for action on Tuesday to prevent a repeat of an epidemic of the mosquito-borne chikungunya virus that swept the globe two decades ago, as new outbreaks linked to the Indian Ocean region spread to Europe and other continents.

An estimated 5.6 billion people live in areas across 119 countries at risk from the virus, which can cause high fever, joint pain and long-term disability, Diana Rojas Alvarez, a medical officer at the WHO, told reporters in Geneva.

"We are seeing history repeating itself," she said, drawing parallels to the 2004-2005 epidemic, which affected nearly half a million people, primarily in small island territories, before spreading around the world.

The current surge began in early 2025, with major outbreaks in the same Indian Ocean islands which were previously hit, including La Reunion, Mayotte and Mauritius.

An estimated one-third of La Reunion's population has already been infected, Rojas Alvarez said. The virus is now spreading to countries such as Madagascar, Somalia and Kenya, and has shown epidemic transmission in Southeast Asia, including India.

Of particular concern is the increasing number of imported cases and recent local transmission within Europe.

There have been approximately 800 imported chikungunya cases in continental France since May 1, Rojas Alvarez said.

Twelve local transmission episodes have been detected in several southern French regions, meaning individuals were infected by local mosquitoes without having travelled to endemic areas. A case was also detected last week in Italy.

Chikungunya, for which there is no specific treatment and which is spread primarily by Aedes mosquito species, including the "tiger mosquito" which also transmits dengue, and Zika, can cause rapid and large outbreaks. As the mosquitoes bite in the daytime, prevention is key, through the use of insect repellent and long-sleeved clothing.