Chikungunya virus disease- Global situation

CHIKV disease is an Aedes-borne disease widely distributed in tropical and subtropical regions. 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. Chikungunya can be introduced to new areas by viremic travelers and generate local transmission in the presence of competent vectors, an immunologically susceptible population and favorable environmental conditions.

Factors associated with increased CHIKV transmission include:

broader geographic range of Aedes mosquitoes associated with transport of immature stages in goods and vessels, and expansion of conducive mosquito habitats due to climate change and periodic extreme events, with increased potential for chikungunya transmission in previously unaffected areas; unplanned urbanization and poor water management contribute to vector reproduction and persistent transmission cycles; low coverage or lack of sustainability of the vector control programs.political instability and conflict in countries at risk, such as Somalia, Sudan, and Yemen face exacerbated public health challenges include disruption of healthcare infrastructure hampering case detection and outbreak response; increased travel to and from endemic regions introducing cases into areas with established populations of competent mosquito vectors and favorable environmental conditions.

The public health impact of the outbreaks depends on several factors, including the ability to detect chikungunya transmission, overall capacities for a coordinated public health response and clinical management, and the proportion of the population immunologically susceptible to CHIKV infection (i.e., people not previously infected with CHIKV). Young children, elderly individuals, and those with pre-existing health conditions such as diabetes, hypertension, and cardiovascular diseases are at higher risk of developing severe disease. Additionally, people living in areas with high mosquito populations and inadequate vector control measures are at greater risk of being infected. Effective public health strategies such as vector surveillance and control, and community education, are crucial in reducing the risk infection for susceptible individuals and preventing outbreaks.

In some areas, there is a lack of medical facilities with limited geographical access, making it difficult for people to access basic health care. Other challenges can be stockouts of several essential supplies for prevention and control, lack of reagents and consumables for laboratory diagnosis, and need for re-training field teams and health workers.

Given the ongoing outbreaks reported globally in 2025, the potential for further spread remains significant. Although some WHO Regions are currently reporting lower case numbers compared to 2024, others are experiencing a resurgence with significant increases in case numbers, furthermore some countries are seeing an emergence of chikungunya in previously unaffected populations. This uneven distribution of cases across regions makes it challenging to characterize the situation as a global rise but rather substantial increases in particular geographical areas. Further, the potential for geographic spread remains substantial given that chikungunya can be introduced into new areas by infected travelers where local transmission may be established in the presence of Aedes mosquito and a susceptible population. The risk is heightened by limited population immunity in previously unaffected areas, favorable environmental conditions for vector breeding, gaps in surveillance and diagnostic capacity, and increased human mobility and trade. Strengthening surveillance, enhancing vector surveillance and control, and improving public health preparedness are essential to mitigate the risk of further transmission.