Mosquito-borne Chikungunya Virus Resurges After Two Decades

The World Health Organization (WHO) issued an urgent call for action July 22 to prevent another epidemic of the mosquito-borne Chikungunya virus that swept the globe two decades ago.

According to Reuters, new outbreaks linked to the Indian Ocean region spread to Europe and other continents. An estimated 5.6 billion people from across 119 countries are at risk from the virus, Diana Rojas Alvarez, a medical officer at the WHO, reported.

According to the U.S. Centers for Disease Control and Prevention (CDC) as of July 1, there have been no locally acquired cases of chikungunya in the U.S. since 2019. Countries with elevated risk for U.S. travelers include Brazil, Columbia, India, Mexico, Nigeria, Pakistan, Philippines, and Thailand.

“We are seeing history repeating itself,” Rojas Alvarez said, drawing parallels to the 2004-05 epidemic, which affected nearly half a million people.

The current surge began in early 2025 and can cause high fever, joint pain, and long-term disability. Major outbreaks have occurred at the same Indian Ocean islands which were previously hit. 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.

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