Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc

Grounds assessments

activeAutochthonous chikungunya transmission will be documented in at least one additional Chinese province beyond Guangdong during the 2026 warm season (May–October), confirmed by national health authority or peer-reviewed publication.50%activeLa Réunion 2026 chikungunya outbreak will exceed 100,000 cumulative reported cases by August 31 2026, based on the 47,500+ case trajectory as of April 2026 and the historical precedent of the 2005-2006 Réunion epidemic reaching 266,000 cases over a longer surveillance period, given that 2026 surveillance capacity and reporting speed are substantially higher than 2005.60%activeECDC will issue a rapid risk assessment or seasonal preparedness alert specifically addressing La Réunion and/or Mayotte chikungunya importation risk for Mediterranean Europe (Italy, Spain, France, Greece) before the 2026 vector season peak (by July 1, 2026), given the 47,500+ case scale of the La Réunion outbreak and established Aedes albopictus populations in Southern Europe.50%resolvedLa Réunion chikungunya outbreak will sustain >10,000 cumulative reported cases through at least July 31 2026, maintaining active seeding pressure on metropolitan France during the peak Aedes albopictus transmission window.70%activeViremic travelers from La Réunion will seed at least one documented autochthonous chikungunya cluster (≥2 locally-acquired cases) in Italy, Spain, or Greece during the 2026 vector season (July–October), given the scale of the current La Réunion outbreak (47,500+ cases) and established Aedes albopictus populations in Mediterranean Europe.50%activeFirst confirmed autochthonous dengue or chikungunya transmission in the UK, Netherlands, Belgium, or Germany will be documented during the 2026 or 2027 Northern Hemisphere transmission season (June–October).30%activeSpain will document ≥500 autochthonous chikungunya cases in the 2026 vector season (April–October 2026), confirming the expanded transmission window as epidemiologically significant and establishing a quantitative baseline for the 2027 autochthonous cycle.50%activeSpain will document autochthonous chikungunya transmission in 2027 season with ≥100 confirmed cases, establishing consecutive-year (2026-2027) endemic seasonal transmission status in mainland Spain60%activeChikungunya will establish autochthonous transmission in at least one subtropical East Asian city outside Guangdong Province (e.g., Taiwan, South Korea, or Japan) during the 2026 or 2027 vector season, based on the documented 2025 Guangzhou urban epidemic demonstrating CHIK transmission competence in a temperate-subtropical East Asian megacity.40%

Evidence content

Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc — research event update (updated 2026-04-13T21:05)

Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc

Field	Value
date	2026-04-13
event_type	who-don
headline	Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc
research_domain	generic
scope	arbovirus
source_meta	{"source":{"sourceId":"who-don","name":"WHO Disease Outbreak News","tier":"T1","url":"https://www.who.int/emergencies/disease-outbreak-news","documentUrl":"https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON567","documentTitle":"Chikungunya - La R\u00e9union and Mayotte"},"hypothesisLinks":[{"hypothesisId":"hyp:arbovirus:2027-10-31:2026-04-13","direction":"supports","weight":0.417}],"flags":[],"direction":"supports","relevanceScore":0.417,"publishedAt":"2025-05-12T15:53:32.000Z","metadata":{"listingUrl":"https://www.who.int/emergencies/disease-outbreak-news","extractionMethod":"who-don-api","articleExtractionMethod":"dom-content","formattedDate":"12 May 2025","emergencyEventUrl":null,"regionscountries":["1c8e9fa9-fd11-40bb-bf06-0ca52d115683"],"language":"en","extractedTitle":"Chikungunya - La R\u00e9union and Mayotte","claimLevel":true,"reportType":"disease_outbreak_news","scopeHints":["arbovirus"],"claimRole":"supporting_detail","claimOrdinal":0,"claimFingerprint":"20b563bb01b1a64967252c922d6a1683fdb22e850a1faa77c9f57180e29b0b16","signalClass":"outbreak","pathogens":["chikungunya"],"hosts":[],"places":[],"country":null,"location":"","canonicalPlaceIds":[],"lineages":[],"mutations":[],"resistanceGenes":[],"counts":{"cases":0,"deaths":0,"samples":0},"studyType":null,"certainty":null,"classification":{"strategy":"keyword-v1","scopeId":"arbovirus","hypothesisMatches":1,"scopeRelevance":0.07692307692307693}}}
source_url	https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON567
summary	Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission occur annually in several countries and territories around the world, the Indian Ocean islands have not experienced major outbreaks for nearly two decades.

Technical metadataPipeline attribution for verification

Connector: —
Payload kind: —
Run ID: —
Schema version: —

Assessment unavailable

This assessment could not be loaded right now because no recent cached snapshot is available.

Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc — research event update (updated 2026-04-13T21:05)

Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc

Field	Value
date	2026-04-13
event_type	who-don
headline	Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission oc
research_domain	generic
scope	arbovirus
source_meta	{"source":{"sourceId":"who-don","name":"WHO Disease Outbreak News","tier":"T1","url":"https://www.who.int/emergencies/disease-outbreak-news","documentUrl":"https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON567","documentTitle":"Chikungunya - La R\u00e9union and Mayotte"},"hypothesisLinks":[{"hypothesisId":"hyp:arbovirus:2027-10-31:2026-04-13","direction":"supports","weight":0.417}],"flags":[],"direction":"supports","relevanceScore":0.417,"publishedAt":"2025-05-12T15:53:32.000Z","metadata":{"listingUrl":"https://www.who.int/emergencies/disease-outbreak-news","extractionMethod":"who-don-api","articleExtractionMethod":"dom-content","formattedDate":"12 May 2025","emergencyEventUrl":null,"regionscountries":["1c8e9fa9-fd11-40bb-bf06-0ca52d115683"],"language":"en","extractedTitle":"Chikungunya - La R\u00e9union and Mayotte","claimLevel":true,"reportType":"disease_outbreak_news","scopeHints":["arbovirus"],"claimRole":"supporting_detail","claimOrdinal":0,"claimFingerprint":"20b563bb01b1a64967252c922d6a1683fdb22e850a1faa77c9f57180e29b0b16","signalClass":"outbreak","pathogens":["chikungunya"],"hosts":[],"places":[],"country":null,"location":"","canonicalPlaceIds":[],"lineages":[],"mutations":[],"resistanceGenes":[],"counts":{"cases":0,"deaths":0,"samples":0},"studyType":null,"certainty":null,"classification":{"strategy":"keyword-v1","scopeId":"arbovirus","hypothesisMatches":1,"scopeRelevance":0.07692307692307693}}}
source_url	https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON567
summary	Chikungunya - La Réunion and Mayotte. Although chikungunya outbreaks and endemic transmission occur annually in several countries and territories around the world, the Indian Ocean islands have not experienced major outbreaks for nearly two decades.