Yellow Fever is a serious viral infection spread by infected mosquitoes, primarily found in tropical and subtropical regions of Africa and South America. It is an acute hemorrhagic disease that can cause jaundice, giving it its name, and can be life-threatening.
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Yellow Fever has caused devastating epidemics for centuries, significantly impacting human history and major construction projects like the Panama Canal. In the early 20th century, research led by Walter Reed confirmed that mosquitoes transmit the virus. A highly effective vaccine was later developed in the 1930s by Max Theiler.
Yellow Fever is transmitted to humans through the bite of infected *Aedes* and *Haemagogus* mosquitoes. These mosquitoes acquire the virus by feeding on infected humans or non-human primates (monkeys). The disease cannot be spread directly from person to person.
Contagious Period: Varies by disease
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Yellow fever cases in the Americas are emerging in both endemic and previously unaffected regions. This suggests that sylvatic transmission is expanding into montane and transitional forest areas, raising concerns about cross-border spread and the risk of urban reintroduction.Country reportsBoliviaColombiaCosta RicaEcuadorVenezuela
Source: BEACON - View Full Report
Brits with travel plans to certain destinations have been put on alert as cases of a dangerous viral illness have surged in recent years. In 2025, yellow fever cases rocketed to 5.6 times the number recorded the year before. Yellow fever is transmitted by mosquitoes across parts of Africa, Central and South America, and in Trinidad in the Caribbean. The disease can trigger severe illness that may prove fatal. In a fresh update, Travel Health Pro warned that yellow fever poses a risk across 13 countries and territories within South and Central America. A significant number of cases were recorded from this region in 2025, with 346 confirmed human cases (including 143 deaths) spanning seven countries. This represents a 5.6-fold increase in cases compared to 2024. Since the start of 2026, a to...
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Venezuela reports 36 confirmed yellow fever cases across 14 states from June 2025 to January 2026 and extensive epizootic activity in eight states, marking the country's most significant yellow fever event since 2005. The outbreak is part of regional intensification across South America during 2024–2026, with the virus spreading beyond traditional endemic areas to previously low-risk regions. An emergency vaccination campaign targeting four priority states aims to rapidly increase population immunity during the peak transmission season, though coverage gaps and geographic limitations may constrain outbreak control.
Source: BEACON - View Full Report
This event envelope contains reports on yellow fever cases and outbreaks in Bolivia.Yellow fever situation in the Americas
Source: BEACON - View Full Report
Colombia's yellow fever outbreak continues into 2026, with 30 confirmed cases and 11 deaths reported as of March 17, 2026. Three deaths occurred among Bogotá residents who traveled unvaccinated to endemic areas, highlighting critical gaps in pre-travel health preparedness and public awareness of vaccination timing requirements.See also BEACON's related reports on the Yellow fever situation in the Americas.
Source: BEACON - View Full Report
Costa Rica has confirmed an imported case of yellow fever. This discovery necessitates an immediate public health response to prevent potential local transmission and outbreak of the severe mosquito-borne disease.
This event envelope contains reports on yellow fever in Brazil.
Source: BEACON - View Full Report
Trinidad and Tobago confirmed yellow fever virus in a deceased Red Howler monkey on 24 Mar 2026, indicating active sylvatic transmission in forested areas with no human cases reported. The detection aligns with Trinidad's endemic pattern of periodic wildlife epizootics and has triggered enhanced surveillance, vector control measures, and public health advisories targeting occupational risk groups with forest exposure.
Source: BEACON - View Full Report
Prof Dr Horia Leonard Banciu, a faculty member of the Department of Molecular Biology and Biotechnology within the Faculty of Biology and Geology at Babes-Bolyai University (UBB) in Cluj-Napoca, has been nominated to represent Romania for the 2025 UNESCO Carlos J. Finlay Prize for Microbiology (https://www.unesco.org/en/prizes/carlos-j-finlay). "The international distinction, a benchmark for excellence in research and innovation in microbiology, is awarded biennially by the United Nations Educational, Scientific and Cultural Organization (UNESCO) and bears the name of Cuban microbiologist Carlos Juan Finlay, who discovered the aetiological agent of yellow fever. The prize recognises discoveries, scientific contributions and achievements with a major impact on society and public health," UB...
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You have full access to this article via Jozef Stefan Institute. Flaviviruses infect hundreds of millions of people each year worldwide. Named after the Latin word flavus (meaning yellow) for the founding member, yellow fever virus, this group of viruses includes medically important pathogens that... Source: Nature - Read Full Article
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View WHO Resources →Disease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.
Last reviewed: 2026-06-03
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