Yellow fever

Last updated: April 20, 2023

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Yellow fever is an acute viral infection caused by the yellow fever virus. Primates are the main reservoir of the virus, which is usually transmitted through bites from infected mosquitoes. Yellow fever is endemic in large parts of South America and Africa. The incubation period is 3–6 days, and the majority of patients remain asymptomatic or experience only mild symptoms. Symptomatic patients initially present with nonspecific symptoms such as sudden-onset fever, malaise, headaches, chills, nausea, and myalgia. Approx. 15% of symptomatic patients progress to the most serious stage of the disease, which can present with life-threatening hemorrhagic fever and organ failure. There is no causal treatment available, making prevention of crucial importance. A single dose of live-attenuated vaccine provides lifelong protection for most individuals.

  • Yellow fever is endemic in tropical regions of South America and Sub-Saharan Africa.
  • Asia, Europe, North America, and Australia are free of yellow fever (except for occasional imported cases).

Yellow fever is endemic in large parts of South America and Africa.


Epidemiological data refers to the US, unless otherwise specified.


  • Incubation time: 3–6 days
  • Clinical features
    • The majority of infected individuals remain asymptomatic.
    • In symptomatic patients: classic progression in three stages
      1. Period of infection (3–4 days)
        • Sudden onset of high fever (up to 41°C, or 105°F)
        • Headaches, chills
        • Nausea, vomiting
      2. Period of remission (up to 2 days)
        • Easing of symptoms and decline in fever
      3. Period of intoxication (only in ∼ 15% of symptomatic patients)

Most patients remain asymptomatic or experience only mild symptoms.


The best test to rule out yellow fever infection is PCR, particularly in the absence of overt symptoms such as fever, headaches, and chills.


The differential diagnoses listed here are not exhaustive.

  • Symptomatic treatment
  • No specific antiviral treatment is available

Avoid NSAIDs that increase the risk of bleeding (e.g., aspirin, ibuprofen, naproxen) in patients with confirmed or suspected yellow fever infection!


We list the most important complications. The selection is not exhaustive.



  1. Jorgensen JH, Pfaller MA. Manual of Clinical Microbiology. ASM Press ; 2015
  2. Yellow Fever. Updated: June 12, 2017. Accessed: August 23, 2017.
  3. Transmission of Yellow Fever Virus . Updated: August 13, 2015. Accessed: August 20, 2017.
  4. Travelers' Health - Yellow Fever. Updated: July 10, 2015. Accessed: March 24, 2017.
  5. Yellow Fever - Symptoms and Treatment. Updated: August 13, 2015. Accessed: August 23, 2017.
  6. CDC Yellow Book. Chapter 4 Travel-Related Infectious Diseases. Yellow Fever. Updated: June 11, 2021. Accessed: November 4, 2022.
  7. Yellow Fever Vaccine. Updated: August 13, 2015. Accessed: August 23, 2017.

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