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.

The United States has rejected amendments adopted in 2024 by members of the World Health Organization (WHO) to its legally-binding health rules aimed at improving preparedness for future pandemics following global response to COVID-19.

The Department of State and Department of Health and Human Services (HHS) reported the official U.S. rejection of the amendments to the International Health Regulations in a statement on July 18, Reuters reported.

The amendments introduced a new category of “pandemic emergency” for the most significant and globally threatening health crises to better prepare for new pathogens.

“Developed without adequate public input, these amendments expand the role of the WHO in public health emergencies, create additional authorities for the WHO for shaping pandemic declarations, and promote WHO’s ability to facilitate ‘equitable access’ of health commodities,” the U.S. statement wrote.

HHS Secretary Robert F. Kennedy Jr., who has a history of sowing doubt about vaccine safety, had slammed the WHO in a video address to the Assembly during its vote on a separate pandemic agreement—which said it had failed to learn from the lessons of the pandemic.

That pact, which was adopted in Geneva in May after three years of negotiations, aims to ensure that drugs, therapeutics, and vaccines are globally accessible if a pandemic hits. It requires participating manufacturers to allocate a target of 20% of their vaccines, medicines, and tests to the WHO during a pandemic to ensure poorer countries have access.

U.S. negotiators left discussions about the accord after President Donald Trump began a 12-month process of withdrawing the U.S.—by far the WHO’s largest financial backer—from the agency in January. Its exit means the U.S. would not be bound by the pact.