Chikungunya epidemiology update - June 2025

Overview

Chikungunya virus (CHIKV) is a mosquito-borne virus primarily transmitted by Aedes mosquitoes. It causes acute illness characterized by fever, rash, and debilitating joint pain, with some patients experiencing long-term joint pain and disabilities. While the overall fatality rate is low, severe disease can occur, especially in vulnerable populations such as infants, the elderly, and those with pre-existing conditions.

The aim of this update is to provide a comprehensive overview of reported data on chikungunya virus globally. This update is based on data submitted by Member States' Ministries of Health to the World Health Organization (WHO) through various surveillance systems, as well as partner organizations that regularly review global CHIKV epidemiological data to identify areas at risk for CHIKV transmission. These data are summarized and contextualized in this first WHO epidemiologic update for chikungunya which will be updated periodically.

As of December 2024, 119 countries and territories have reported local transmission. High attack rates can lead to temporary interruption of transmission in small populations, but larger populations remain at risk due to ongoing susceptibility. Surveillance and diagnostic limitations hinder accurate global tracking, and under-reporting is common. The potential for re-emergence remains high in previously affected areas.