Rapid #risk #assessment: #Chikungunya virus disease, #Global (WHO, 24 April 2026, v2, summary)

{Summary)

Overall Risk statement

-- This rapid risk assessment aims to assess the overall public health risk posed by chikungunya virus (CHIKV) transmission in 2026 at the global level. 

-- It considers the potential risk to human health, the likelihood of geographical spread, limitations in prevention and control capacities, and the influence of regional seasonal patterns that favour Aedes mosquito activity, which could drive outbreaks during the 2026 transmission season. 

-- Chikungunya virus poses a significant and growing global health risk due to large and widespread regional outbreaks in recent years, lack of specific treatment, limited use of vaccine, and climate- and conveyance-driven mosquito range expansion, with increasing international travel. 

-- While mortality remains relatively low, the CHIKV infection can cause prolonged arthritis with disability as well as severe illness in some patients.

-- In 2025, an overall of 502 264 CHIKV disease cases including 208 335 confirmed cases, and 186 deaths were reported globally from 41 countries and territories, including autochthonous and imported cases in travellers. 

-- From 1 January to 31 March 2026, Chikungunya transmission was reported by 18 countries, with the vast majority of cases occurring in the Region of the Americas. 

-- Brazil and Bolivia account for 87% of cases in the Region; together with Argentina, Suriname, and Cuba, these five countries represent approximately 99% of reported cases. 

-- The European Region reported the second-highest number of cases, predominantly reported from French overseas departments, particularly Mayotte and La Réunion. 

-- Global aggregation is limited due to incomplete reporting.

-- With the rainy season about to begin in many regions in the coming months, cases of CHIKV are expected to rise, as rainfall events create favourable conditions for Aedes mosquito breeding and increase the risk of CHIKV transmission, including in previously unaffected areas. 

-- Transmission dynamics will also be impacted by the population immunity acquired from outbreaks in recent years. 

-- Peak CHIKV transmission months in the respective WHO regions include:

• Southeast Asia & Western Pacific: May–October

• Americas: May–November (Northern hemisphere)/November–March (Southern hemisphere)

• Continental Europe: June–September (main season) (transmission in overseas departments aligns with climatic conditions within their geographic location/proximity)

• Africa & Eastern Mediterranean: During/after local rainy seasons (varies by country)

-- The global public health risk posed by CHIKV transmission is assessed as moderate. 

-- This takes into account the widespread transmission and outbreaks across multiple WHO regions in 2025, which continued into early 2026, including in areas with previously low or no transmission. 

-- Ongoing transmission in parts of the Indian Ocean region, such as Seychelles, Mauritius and Mayotte demonstrates continued regional activity. 

-- The resurgence and emergence of cases in new geographic areas are facilitated by the presence of competent Aedes mosquito vectors, limited population immunity, favorable environmental conditions, and increased human mobility coupled with under-performing/disrupted health systems, particularly in fragile, conflict-affected and vulnerable countries- leading to poor control measures.

-- The uneven distribution of cases across regions complicates the interpretation of a global trend but highlights significant localized transmission. 

-- Prevention and control capacities remain challenged by gaps in surveillance, equitable access to quality-assured diagnostics and laboratory confirmation, healthcare infrastructure, and sustained vector surveillance and control management.

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Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---chikungunya-virus-disease--global-v.2

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Rapid #risk #assessment, acute event of potential public health concern: #Chikungunya virus disease, #Global (#WHO, Dec. 29 '25, summary)

 

Overall Risk statement

-- This RRA aims to assess the overall public health risk at the global level posed by the chikungunya virus (CHIKV) transmission during 2025, considering the criteria of potential risk for human health, the risk of geographical spread, and the risk of insufficient control capacities with available resources, and the implications for the 2026 transmission season. 

-- Chikungunya virus (CHIKV) poses a significant and growing global health risk due to large and widespread regional outbreaks in recent years, climate-driven mosquito expansion, lack of specific treatment, and increasing international travel. 

-- While mortality remains relatively low, the CHIKV infection can cause prolonged arthritis with disability as well as  severe illness in some patients. 

-- From 1 January to 10 December 2025, 502 264 CHIKV disease cases including  208 335 confirmed cases, and 186 CHIKV deaths, were reported globally. 

-- While certain WHO Regions are reporting lower case numbers compared to 2024, others are experiencing marked increases, furthermore some countries are seeing an emergence of chikungunya in previously unaffected populations. 

-- This heterogeneity in regional trends complicates the interpretation of the global situation. 

-- The data suggest localized resurgence or emergence in specific geographic areas. 

-- The region of the Americas has reported the highest number of confirmed cases followed by the European region (comprised of cases reported predominantly from French Overseas Departments in the Indian Ocean). 

-- Further, the potential for geographic spread remains substantial given that chikungunya can be introduced into new areas by infected travellers where local transmission may be established in the presence of competent Aedes mosquito, a susceptible population and favorable climatic and ecological conditions.  

-- The global public health risk posed by CHIKV transmission is assessed as moderate, driven by widespread outbreaks across multiple WHO regions during the 2025 season including areas with previously low or no transmission. 

-- The resurgence and emergence of cases in new geographic areas are facilitated by the presence of competent Aedes mosquito vectors, limited population immunity, favorable environmental conditions, and increased human mobility. 

-- The uneven distribution of cases complicates global interpretation, but highlights significant localized transmission. 

-- Control capacities remain challenged by gaps in surveillance, diagnostic access, healthcare infrastructure, and sustainable vector surveillance and control.  

-- Given the ongoing outbreaks reported globally in 2025, the potential for further spread in 2026 cannot be ruled out. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---chikungunya-virus--global-v.1

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#Vectors on the Move: How #Climate Change Fuels the Spread of #Arboviruses in #Europe

 

Abstract

Climate change is increasingly recognized as a major driver of emerging infectious diseases, particularly vector-borne diseases (VBDs), which are expanding in range and intensity worldwide. Europe, traditionally considered low-risk for many arboviral infections, is now experiencing autochthonous transmission of pathogens such as dengue, chikungunya, Zika virus, West Nile virus, malaria, and leishmaniasis. Rising temperatures, altered precipitation patterns, and milder winters have facilitated the establishment and spread of competent vectors, including Aedes, Anopheles, Phlebotomus, and Culex species, in previously non-endemic areas. These climatic shifts not only impact vector survival and distribution but also influence vector competence and pathogen development, ultimately increasing transmission potential. This narrative review explores the complex relationship between climate change and VBDs, with a particular focus on pediatric populations. It highlights how children may experience distinct clinical manifestations and complications, and how current data on pediatric burden remain limited for several emerging infections. Through an analysis of existing literature and reported outbreaks in Europe, this review underscores the urgent need for enhanced surveillance, integrated vector control strategies, and climate-adapted public health policies. Finally, it outlines research priorities to better anticipate and mitigate future disease emergence in the context of global warming. Understanding and addressing this evolving risk is essential to safeguard public health and to protect vulnerable populations, particularly children, in a rapidly changing climate.

Source: Microorganisms, https://www.mdpi.com/2076-2607/13/9/2034

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First Isolation and Characterization of #LiaoNing Virus from #Aedes Vexans #Mosquitoes in #Hokkaido, #Japan, in 2022

Abstract

Background: 

The Liao ning virus (LNV), belonging to the genus Seadornavirus within the family Sedoreoviridae, is a mosquito-borne virus. It was originally isolated from Aedes dorsalis mosquitoes in China. The original LNV strain, LNVS-NE97-31, was reported to infect several mammalian cell lines and cause hemorrhagic symptoms in mice. Subsequently, another LNV strain, LNV NSW B115745, was isolated from Australian mosquitoes; it was reported to exhibit insect-specific infection.

Materials and Methods: 

Virus isolation was performed on mosquitoes collected in northern Hokkaido, Japan, in 2022. The isolated virus was subjected to genomic and growth kinetics analyses.

Results: 

A LNV strain was isolated from Aedes vexans mosquitoes. Genomic sequencing and phylogenetic analysis revealed the new strain as 22WN03, and it formed a robust clade with the original Chinese strain, LNVS-NE97-31. Growth kinetics analysis did not reveal any mammalian or avian cell line susceptible to infection by the strain 22WN03.

Conclusion: 

Overall, the results suggested that the strain 22WN03 has insect-specific infection characteristics, similar to as the Australian strain. Taken together, our findings could expand our knowledge of not only the diversity and geographical distribution of seadornaviruses in Asia but also the ecology of LNV.

Source: Vector-Borne and Zoonotic Diseases, https://www.liebertpub.com/doi/abs/10.1177/15303667251364143

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