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Disease intelligence sheet
Yellow fever
Curated desk background for reporters who need the pathogen, transmission, and outbreak frame fast.
Pathogen / agent: Yellow fever virus
Transmission: Mosquito-borne
Reservoir / vector: Mosquito cycles involving non-human primates and humans define the classic ecology.
Incubation: Usually 3 to 6 days.
Severity: Potentially high fatality in the toxic phase.
Diagnostics: PCR and serology, interpreted with vaccination history and geography.
Treatment: Supportive care only.
Prevention: Vaccination remains the decisive preventive tool.
Vaccine / prevention status: Vaccination is highly effective, so outbreaks are usually surveillance-and-coverage failures rather than biomedical mysteries.
Symptoms And Clinical Pattern
- Fever, headache, and myalgias in the early phase.
- A toxic phase can bring jaundice, bleeding, and organ failure.
- Not every case progresses to severe disease, but the severe end is dramatic.
Official Background Links
Current Story Files
No active tracked stories are linked to this disease in the current run.
Why Reporters Care
Why this keeps becoming news: Yellow fever matters because a rise in sylvatic spillover, urban encroachment, or vaccine gaps can turn a seemingly remote arbovirus story into a major regional emergency.
What journalists often get wrong: The common mistake is failing to distinguish forest-cycle spillover from the much scarier possibility of wider urban transmission.
- Confirmed cases and deaths, especially in newly affected geography.
- Whether transmission remains sylvatic or shows signs of urban spread.
- Vaccination coverage, campaign timing, and traveler risk messaging.
Last Major Outbreak On File
Americas resurgence | Bolivia, Brazil, Colombia, Ecuador and Peru | 2025
WHO reported 212 confirmed yellow fever cases and 85 deaths in the Americas as of late April 2025, a threefold increase over 2024 totals.
Source: WHO Disease Outbreak News (2025-05-16)
Desk Notes And Historical Signals
Desk note: When sylvatic transmission escapes its expected geography, this deserves very fast escalation.
Research caveats: Small outbreaks can still matter a lot, and cross-country comparisons are complicated by uneven surveillance and vaccination histories.
- The cited WHO update notes spread beyond the Amazon region into places such as Sao Paulo and Tolima.