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What is it

Yellow fever is a viral disease spread by mosquitoes1. It occurs in tropical and subtropical areas of Africa and South America1. Its name is derived from the yellowing of the skin and eyes (jaundice) that occurs when the virus attacks the liver1. Illness ranges in severity from self-limited febrile cases to severe liver damage with bleeding1.

Who is at risk

Risk of developing yellow fever depends on several factors including1:

  • Destination
  • Time of the year (season)
  • Duration of travel
  • Activities done during the trip

Risk is higher for travellers who are going to areas of risk (e.g. tropical areas of Africa and South America) and who are staying for an extended period of time, visiting rural or jungle areas or participating in outdoor activities including camping, hiking cycling or fieldwork1.

What are the symptoms

Symptoms develop within 3 to 6 days1. Initial symptoms include1:

  • Sudden onset of fever
  • Chills
  • Headache
  • Joint and muscle pain
  • Loss of appetite
  • Abdominal pain, back pain
  • Nausea, vomiting
  • Fatigue, weakness
  • Dehydration

In severe cases yellow fever can cause1:

  • Shock
  • Internal bleeding
  • Jaundice (yellow of the skin and whites of the eyes)
  • Organ failure

How is it spread

Yellow fever is a disease caused by a flavivirus1. Yellow fever is spread through the bite of infected mosquitoes, mainly the Aedes species in Africa and the Haemagogus species in South America1. Mosquitoes that spread yellow fever typically bite during the daytime, particularly around sunrise and sunset1.

How is it prevented

Consult your healthcare provider or visit a travel clinic (preferably six weeks or more) prior to travelling1. Get vaccinated at designated yellow fever vaccination centres.2

The single-dose vaccine is effective and recommended for most people over nine months of age1,2. When given the vaccine for the first time, it takes ten days for it to become effective1,2.

Protect yourself from mosquito bites, particularly around sunrise and sunset1.

How is it treated

There is no specific treatment for yellow fever, only supportive care to relieve symptoms1.


  1. Government of Canada. Yellow Fever. (2016).
  2. Sanofi Pasteur YF-VAX Product Monograph. (2009)