Yellow fever is an epidemic-prone, vaccine-preventable disease caused by a virus transmitted by infected Aedes s.p., Haemagogus s.p., and Sabethes s.p. mosquitoes [1]. These mosquitoes breed in domestic, forest (sylvatic), and semi-domestic environments [1].
Disease overview
Yellow fever
黄热病
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Yellow fever is an epidemic-prone, vaccine-preventable viral disease caused by a virus transmitted by infected Aedes s.p., Haemagogus s.p., and Sabethes s.p. mosquitoes [1][2]. These mosquitoes breed in domestic, forest (sylvatic), and semi-domestic environments [1]. Approximately 15% of infected individuals develop severe disease characterized by jaundice, haemorrhage, organ failure, and approximately 50% fatality among severe cases [1][3]. Despite the availability of a safe and effective vaccine, yellow fever remains a major public health threat due to its epidemic potential and risk of international spread [4][5].
Read the full clinical and epidemiological profile6
The incubation period ranges from 3 to 6 days [1][3]. Initial symptoms include fever, headache, muscle pain with prominent backache, loss of appetite, and nausea or vomiting, which typically disappear after 3 to 4 days [1][3]. Approximately 15% of patients enter a second, more toxic phase within 24 hours of recovering from initial symptoms, presenting with high fever recurrence, jaundice, dark urine, abdominal pain, and bleeding from the mouth, nose, eyes, or stomach; about 50% of these patients die within 7 to 10 days [1][3]. Yellow fever is difficult to diagnose early when clinical manifestations are nonspecific; severe cases may resemble malaria, leptospirosis, viral hepatitis, dengue, or poisoning [1][3].
Yellow fever occurs in 47 endemic countries in Sub-Saharan Africa and Central and South America, with approximately 90% of reported cases annually occurring in Sub-Saharan Africa [2]. During outbreaks, WHO estimates that actual cases may be 10 to 250 times higher than reported [1]. Rapid detection and laboratory confirmation, along with emergency vaccination, are critical to control outbreaks; high-risk countries should maintain at least one national laboratory for yellow fever testing [1]. Although infected travellers can export cases to non-endemic countries, disease spread requires local mosquito species, specific climatic conditions, and animal reservoirs [2]. The disease has historically played a significant geopolitical role in shaping modern societies [4].
Yellow fever virus is transmitted by infected mosquitoes, primarily Aedes s.p. species—the same mosquito that spreads Zika, Chikungunya, and dengue—and Haemagogus mosquitoes found mainly in jungle settings [1][2]. Mosquitoes become infected with the virus when they bite an infected human or monkey; the disease cannot spread through person-to-person contact [2]. Mosquitoes breed in tropical rainforests, humid and semi-humid environments, and around bodies of still water near human habitations in urban settings [1][2]. Increased contact between unvaccinated humans and infected mosquitoes, particularly in urban areas, can create epidemics [2][4].
Vector control includes insecticide-treated bed nets, though these are less effective for day-biting mosquitoes; vector surveillance, especially of Aedes aegypti, helps assess urban outbreak risk [1]. WHO recommends a single dose of yellow fever vaccine, which provides lifelong protection, incorporated into routine immunization schedules for endemic areas [1][3][4]. Emergency vaccination is critical during outbreaks; the Eliminate Yellow Fever Epidemics (EYE) Strategy 2017–2026 guides prevention efforts [2][4]. Rapid detection and laboratory confirmation, followed by case investigation and emergency immunization, are essential response measures [1].
- 1World Health Organization. Yellow fever [Internet]. cited 3 Sept 2026.Available from: https://www.who.int/news-room/fact-sheets/detail/yellow-fever
- 2World Health Organization. Yellow fever [Internet]. cited 3 Sept 2026.Available from: https://www.who.int/news-room/questions-and-answers/item/yellow-fever
- 3World Health Organization. Yellow fever [Internet]. cited 3 Sept 2026.Available from: https://www.who.int/health-topics/yellow-fever
- 4Tuells J et al. Yellow Fever: A Perennial Threat. Arch Med Res. 2022 Nov. PMID: 36404585. doi: 10.1016/j.arcmed.2022.10.005.PubMed: https://pubmed.ncbi.nlm.nih.gov/36404585/
- 5Srivastava S et al. Yellow Fever: Global Impact, Epidemiology, Pathogenesis, and Integrated Prevention Approaches. Infez Med. 2024. PMID: 39660161. doi: 10.53854/liim-3204-3.PubMed: https://pubmed.ncbi.nlm.nih.gov/39660161/
- A95
- 1D48
Coverage
Reporting countries and regions
AustriaAT
BelgiumBE
BulgariaBG
CanadaCA
CroatiaHR
CyprusCY
CzechiaCZ
DenmarkDK
EstoniaEE
FinlandFI
FranceFR
GermanyDE
GreeceGR
Hong Kong, ChinaHK
HungaryHU
IcelandIS
IrelandIE
ItalyIT
JapanJP
LatviaLV
LiechtensteinLI
LithuaniaLT
LuxembourgLU
MaltaMT
NetherlandsNL
NorwayNO
PolandPL
PortugalPT
RomaniaRO
SingaporeSG
SlovakiaSK
SloveniaSI
South KoreaKR
SpainES
SwedenSE
SwitzerlandCH
United KingdomGB
United StatesUS
Trends by reporting country
Monthly patterns over time
Research Radar
Recent related research
Emergence and phylogeography of the dengue vector Aedes aegypti in Southeastern Iran
PLOS Neglected Tropical Diseases
Systemic barriers to achieving yellow fever vaccination coverage targets among children aged 9–23 months in the Democratic Republic of the Congo
Vaccine
Investigating antibody cross-reactivity and transmission dynamics of alphaviruses and flaviviruses using a multiplex serological assay
Nature Communications
Reemergence of yellow fever virus in southeastern Brazil, 2017–2018: What sparked the spread?
PLOS Neglected Tropical Diseases
Spatial epidemiology of yellow fever: Identification of determinants of the 2016-2018 epidemics and at-risk areas in Brazil
PLOS Neglected Tropical Diseases
Showing 5 of 10 related publications.
Literature links are provided for discovery and do not alter or validate the surveillance series above.
Data access
Page dataset index with source links and update metadata.
Official sourcesAuthority, cadence, notes43
Austria AGES Radar for Infectious Diseases
Austria
AGES Radar monthly national source. Internal ingestion retains native categories; public release is disabled pending licence review.
ECDC Surveillance Atlas — Belgium Annual Baseline
Belgium
Belgium annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Bulgaria Annual Baseline
Bulgaria
Bulgaria annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Canada PHAC CNDSS Annual
Canada
Canada is the national jurisdiction; subdivision feeds are registered separately.
Switzerland FOPH IDD
Switzerland
Switzerland FOPH/BAG IDD mandatory reporting API normalized to national case rows. Monthly series may use the dashboard CHFL aggregate where CH-only monthly series are not exposed.
ECDC Surveillance Atlas — Cyprus Annual Baseline
Cyprus
Cyprus annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Czechia Annual Baseline
Czechia
Czechia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Germany RKI SurvStat 2.0
Germany
RKI SurvStat national weekly notification export; raw ZIP exports are retained and recent weeks are overwritten for revisions.
ECDC Surveillance Atlas — Denmark Annual Baseline
Denmark
Denmark annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Estonia Annual Baseline
Estonia
Estonia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Spain Annual Baseline
Spain
Spain annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Finland THL Infectious Diseases Register
Finland
Finland THL Infectious Diseases Register national monthly case counts. The current month is ingested as provisional and the latest three months are refreshed for source revisions.
ECDC Surveillance Atlas — France Annual Baseline
France
France annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — United Kingdom Annual Baseline
United Kingdom
United Kingdom annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Greece Annual Baseline
Greece
Greece annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Hong Kong, China CHP Notifiable Diseases
Hong Kong, China
Hong Kong, China CHP annual notifiable infectious disease CSVs normalized to national monthly totals
ECDC Surveillance Atlas — Croatia Annual Baseline
Croatia
Croatia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Hungary Annual Baseline
Hungary
Hungary annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Ireland HPSC Notifiable Diseases Hub
Ireland
Ireland HPSC national weekly notifiable-disease totals from the official ArcGIS FeatureServer. Internal ingestion is enabled; public release remains disabled pending written redistribution permission.
Iceland Directorate of Health Annual Dashboard
Iceland
National annual case notifications by disease. Published values can be revised retrospectively and remain annual period totals.
Iceland Directorate of Health STI Dashboard
Iceland
Monthly STI diagnosis facts from laboratory and registry surveillance; the official dashboard is published on a quarterly schedule.
Iceland Directorate of Health Respiratory Dashboard
Iceland
ISO-week respiratory diagnosis counts. Hospitalizations, samples, and vaccination indicators are separate measures and are not counted as diagnoses.
Iceland Directorate of Health Historical Registry
Iceland
Historical official registry tables for 1997–2021, with annual totals and disease-specific monthly notification facts retained at source grain.
Iceland Directorate of Health Legacy ICD Monthly
Iceland
Historical Saga EHR ICD encounter counts for 1997–2020. This clinical measure is non-comparable with registry notifications and is kept separate.
ECDC Surveillance Atlas — Italy Annual Baseline
Italy
Italy annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
JP NIID Weekly
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.
Korea KDCA EID
South Korea
Korea KDCA notifiable infectious disease OpenAPI or portal/KOSIS downloads aggregated to national monthly notification counts.
ECDC Surveillance Atlas — Liechtenstein Annual Baseline
Liechtenstein
Liechtenstein annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Lithuania Annual Baseline
Lithuania
Lithuania annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Luxembourg Annual Baseline
Luxembourg
Luxembourg annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Latvia Annual Baseline
Latvia
Latvia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Malta Annual Baseline
Malta
Malta annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Netherlands Annual Baseline
Netherlands
Netherlands annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Norway FHI MSIS Statistics Bank
Norway
Norway FHI MSIS national monthly notifications from the official Allvis frontend API; adapter contract checks guard the unversioned endpoint.
ECDC Surveillance Atlas — Poland Annual Baseline
Poland
Poland annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Portugal Annual Baseline
Portugal
Portugal annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Romania Annual Baseline
Romania
Romania annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Sweden Public Health Agency SmiNet
Sweden
Sweden SmiNet national monthly reported cases from the official Public Health Agency statistics pages; public release is enabled with closed-month publication and revisable recent-month refreshes.
Singapore CDA Weekly Infectious Diseases Bulletin
Singapore
Singapore national weekly case notifications, combining the official data.gov.sg 2012–2022 CSV history with CDA annual workbooks from 2023 onward; 2023 weekly PDFs are retained as a source fallback.
ECDC Surveillance Atlas — Slovenia Annual Baseline
Slovenia
Slovenia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Slovakia Annual Baseline
Slovakia
Slovakia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
US CDC NNDSS
United States
CDC National Notifiable Diseases Surveillance System provisional data.
US CDC NHSS HIV
United States
CDC NNDSS weekly data plus NHSS annual national HIV diagnoses