Definition: Yellow Fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes, primarily *Aedes aegypti*, which can cause a range of symptoms from mild fever to severe liver damage with jaundice, hemorrhage, and multi-organ failure.
Caused by a flavivirus, Yellow Fever virus is transmitted to humans through the bite of infected female mosquitoes, predominantly *Aedes aegypti* in urban and intermediate settings, and *Haemagogus* species in jungle environments. The disease is endemic in tropical and subtropical regions of Africa and South America, where it poses a significant public health threat. After an incubation period of 3-6 days, symptoms can appear, initially resembling a flu-like illness with fever, muscle pain, headache, and nausea. In a subset of patients (around 15%), the disease progresses to a more severe and toxic phase characterized by high fever, jaundice (yellowing of the skin and eyes due to liver damage), abdominal pain with vomiting, and hemorrhagic manifestations such as bleeding from the mouth, nose, eyes, or stomach.
The public health importance of Yellow Fever stems from its potential for severe epidemics, high case fatality rates in severe cases (30-60%), and the absence of specific antiviral treatment, making prevention crucial. Historically, Yellow Fever has caused devastating epidemics, significantly impacting global trade and development. The primary and most effective preventive measure is vaccination, with a single dose providing lifelong immunity for most individuals. Public health strategies focus on comprehensive surveillance, rapid outbreak response, vector control measures (e.g., eliminating mosquito breeding sites), and mass vaccination campaigns in at-risk populations. Global initiatives, such as the Eliminate Yellow Fever Epidemics (EYE) strategy led by WHO, UNICEF, and Gavi, aim to prevent future outbreaks and save lives through improved vaccination coverage, robust surveillance, and rapid response mechanisms.
Key Context:
- Highly effective vaccine available for prevention.
- Transmitted by *Aedes* and *Haemagogus* mosquitoes (vector-borne disease).
- A flavivirus, related to Dengue and Zika viruses.