Chikungunya surge in the Americas since late 2025: A call to strengthen surveillance and response capacities

9 MARCH 2026, WASHINGTON, D.C. —

Between late 2025 and the first weeks of 2026, a sustained increase in chikungunya cases has been observed in several countries and territories of the Americas Region, along with the reemergence of autochthonous transmission in areas that had not reported virus circulation for several years. This pattern reinforces the need for countries to maintain strong surveillance and ensure a timely response.

Globally, from 1 January to 10 December 2025, 502 264 cases of chikungunya were reported by 41 countries and territories, including 208 335 confirmed cases and 186 deaths. Three main chikungunya virus (CHIKV) genotypes circulate globally (West African, East/Central/South African [ECSA] and Asian), which differ in their geographic spread, epidemic potential, and adaptation to mosquito vectors such as Aedes aegypti and Aedes albopictus.

In the Americas Region during 2025, 18 countries and one territory reported 313 132 chikungunya cases, of which 113 926 were laboratory-confirmed. Countries also reported 170 chikungunya-related deaths (Figure 1). During the last four weeks of 2025 (EW 49) and the first weeks of 2026 (EW 4), continued circulation has been observed in the Central-West and Southeast regions of Brazil, southern Bolivia, and with reappearance of cases in the Guiana Shield area (Figure 2). By EW 4 of 2026, 7 150 cases had been reported in the Americas, including 2 351 confirmed cases and one death.

Figure 1. Distribution of chikungunya cases by year and epidemiological week in the Americas Region, 2022–2026.

Source: Adapted from Pan American Health Organization. PLISA Health Information Platform for the Americas, Chikungunya Indicators Portal. Washington, D.C.: PAHO/WHO; 2026 [Accessed February 5, 2026]. Available at: https://www.paho.org/en/arbo-portal/chikungunya-data-and-analysis/chikungunya-analysis-country

Figure 2. Geographic distribution of chikungunya cases in the Americas Region, SE 49 of 2025 to SE 4 of 2026.

Source: Adapted from data provided by the respective countries and reproduced by PAHO/WHO.

Although case numbers in early 2026 remain lower than those from the same period in 2025, persistent transmission during the final weeks of 2025 and into early 2026 suggests ongoing viral circulation with potential for further expansion, particularly in areas with established Aedes aegypti and Aedes albopictus populations. In most of the affected countries, circulation of the ECSA genotype has been documented through the Pan American Health Organization (PAHO) genomic surveillance networks (PAHOGen). Widely established in the Region in recent years, the ECSA genotype’s ongoing circulation reflects sustained transmission dynamics and the potential for further geographic expansion, particularly in areas with competent vector populations. So far, the A226V mutation within the ECSA genotype, which might facilitate viral replication in Aedes albopictus, has not been identified in the Americas Region.

Discussion

The current epidemiological pattern raises concern for short- and medium-term regional expansion. Several contextual factors may facilitate further spread, including accumulation of susceptible populations following periods of reduced transmission, favorable climatic conditions for vector proliferation, high cross-border mobility, and active commercial and transportation corridors.

The concentration of cases in geographically strategic areas, particularly characterized by intense population movement, may increase the likelihood of subnational and transnational spread. Additionally, the resurgence of autochthonous transmission in previously silent areas underscores the importance of strengthening surveillance sensitivity for early detection and rapid public health action.

In response to the evolving epidemiological situation, PAHO issued an Epidemiological Alert urging Member States to intensify epidemiological and laboratory surveillance, ensure early detection and appropriate clinical management of cases, and consolidate integrated vector control measures. Preparing health services for potential increases in case load is essential to limit morbidity and prevent deaths.

Sustained surveillance, including strengthening laboratory confirmation of cases, enhanced analytical processes and coordinated regional action will be key to mitigating further spread and reducing the impact of Chikungunya in the Americas.

RECOMMENDATIONS

In light of the current situation, Member States are urged to strengthen surveillance and response capacities. Countries are encouraged to maintain sensitive epidemiological and entomological surveillance systems, including the timely detection of unusual events and changes in transmission patterns.

Key takeaways:

• Sustained transmission with geographic expansion risk: Chikungunya transmission has persisted from late 2025 into early 2026, with reemergence in previously silent areas and notable circulation in strategically connected regions, increasing the risk of further spread.

• ECSA genotype continues to predominate: In most of these countries, circulation of the ECSA genotype has been documented, which may have implications for transmission dynamics.

• Regional conditions enable further spread: Accumulation of susceptible populations, climatic suitability, and high mobility across borders create a conducive environment for short- and medium-term expansion if surveillance and response are not sustained.

• Strengthened surveillance and coordinated response are essential: Maintaining sensitive epidemiological and entomological surveillance, timely laboratory confirmation, integrated vector management, and adherence to IHR (2005) information-sharing mechanisms will be critical to mitigating further spread and reducing public health impact.

At the same time, continuous risk assessment and transparent information-sharing, in accordance with the International Health Regulations (2005), are essential to mitigate potential cross-border spread. At the national and local level, risk communication and community participation are key components to reduce vector breeding sites and limit transmission.

Ensuring timely laboratory confirmation—preferably through molecular testing during the acute phase and, when necessary, through rapid decentralization of testing at subnational levels—should be prioritized, along with strengthened clinical management capacities across all levels of care, particularly for populations at higher risk of severe outcomes; namely, neonates and infants, persons at any age with underlying conditions, and the elderly. Health services should remain prepared for potential increases in demand during periods of intensified transmission. Likewise, integrated vector management strategies, including environmental management, targeted control measures, and community engagement, should be sustained and adapted to local transmission dynamics.

Across all these actions, the technical guidance issued in previous PAHO Epidemiological Alerts and regional laboratory recommendations remains applicable and should continue to guide national response efforts.

Funding Statement

PAHO.

Data Availability Statement.

Data available from Epidemiological Alert on chikungunya