Symptoms

• Can take 3 to 6 days to appear.
• Usually include sudden onset of fever, headache, joint pain, loss of appetite, abdominal pain, vomiting and dehydration. Most patients recover after this stage.
• In severe cases, the disease can lead to shock, internal bleeding, jaundice (yellowing of the skin and eyes) and organ failure. This occurs in about 15% of patients. The case-fatality rate for those who develop severe yellow fever disease is 20-50%.

Transmission

• Yellow fever is spread through the bite of infected mosquitoes — mainly Aedes aegypti but with other Aedes species in Africa and Haemagogus species in South America also playing a role in transmission.
• These mosquitoes can be domestic (i.e. they breed around houses), wild (they breed in the jungle), or semi-domestic types (they display a mixture of habits). Any region populated with these mosquitoes can potentially harbour the disease.
• Non-human primates (e.g., monkeys) can also be infected with the yellow fever virus; this allows for the virus to remain present in rural or jungle areas without human hosts.
• Yellow fever epidemics occur in urban areas when infected people carry the disease from rural or jungle areas into densely populated areas where there are mosquitoes capable of spreading the disease.

Where is Yellow Fever a Concern?

• Yellow fever is endemic (always present) in many tropical areas of South America and Africa.
  • In South America, the countries considered to have the greatest risk of contracting yellow fever include Bolivia, Brazil, Colombia, Ecuador and Peru. Several Caribbean islands are also at low risk for epidemics.
  • Countries at risk for yellow fever in Africa are typically situated on or around the equator.
  • Yellow fever is not endemic in Asia, however since both the mosquitoes and the non-human primates are present in different parts of Asia, there is potential for future epidemics.

A list of countries where yellow fever transmission occurs is available from the World Health Organization.

Related Travel Health Notices

None

Recommendations for Travellers

Consult a doctor, nurse or health care provider, or visit a travel health clinic preferably six weeks before you travel.

1. Get vaccinated
   1. It is recommended that you get the yellow fever vaccine before you travel if you are:
      • travelling to a country that requires proof of yellow fever vaccination to enter (International Certificate of Vaccination or Prophylaxis).
        • It is also recommended that you contact the nearest diplomatic or consular office of the destination(s) you will be visiting to verify additional entry requirements.
      • travelling to a country or area where there is a risk of yellow fever ;
        • A map of countries and areas in Africa and the Americas where yellow fever vaccination is recommended is available from the WHO.
        • There are exceptions in areas with a low potential for exposure to the yellow fever virus, where vaccination is generally not recommended.
   2. The single-dose vaccine against yellow fever is safe, effective and recommended for most people who are over nine months of age.
   3. The vaccine is generally not recommended for pregnant or breastfeeding women, children under the age of nine months, adults 60 years and older (especially those who have not previously received the vaccine) and people with weakened immune systems.
   4. It takes 10 days before the vaccine takes effect so leaving vaccination to the last minute will leave you at risk. The vaccine provides immunity for 10 years or more. In Canada, the vaccine is available only at designated Yellow Fever Vaccination Centres.
   
   
   
2. Protect yourself from mosquito bites. Mosquitoes that spread yellow fever usually bite during the day, particularly two to three hours after dawn and during the early evening:
   1. Cover up: Wear light-coloured, long-sleeved, tucked-in shirts, long pants, shoes (not sandals), and a hat
   2. Use insect repellent on exposed skin:
      • Of the insect repellents registered in Canada, those containing DEET are the most effective
      • Use as directed by the manufacturer
      • Do not apply to cuts, abrasions or irritated skin
      • Do not spray directly on face
      • Wash your hands after application, to avoid contact with lips and eyes
      • When using sunscreen: do not use insect repellent and sunscreen combination products
      • If application of sunscreen and repellent with DEET is required, apply the sunscreen first and let it soak into the skin for about 20 minutes, then apply repellent with DEET
      • After returning indoors, wash off repellent.
   3. Sleep under a bed net, preferably treated with insecticide:
      • Ensure the net is intact (no tears or large holes)
      • Tuck it under the mattress
      • Ensure it is not touching you (or you still may be bitten through the net)
   4. Consider your accommodations: Stay in a well-screened or completely enclosed air-conditioned room
   5. Apply a permethrin insecticide to tents and clothing and other travel gear for greater protection
      • Permethrin-treated clothing is effective for up to 2 weeks or 6 washings
      • Although permethrin is not available in Canada, travel health clinics can advise you how to purchase permethrin and pre-treated gear before or during your trip
      • This could be considered for playpens, crib, or strollers to protect young children

More information on precautions to take to avoid mosquito bites while travelling…

Don't Forget …

1. Consult a doctor, nurse, or health care provider or visit a travel health clinic at least six weeks before you travel.
2. What to do if you get sick when you are travelling.
3. What to do if you get sick after you return to Canada
4. Know what vaccines to get and when to get them

Other Related Information

PHAC- Yellow Fever Vaccination Centres in Canada

Committee to Advise on Tropical Medicine and Travel (CATMAT) – Statement for Travellers and Yellow Fever

CATMAT – Statement on Personal Protective Measures to Avoid Arthropod Bites

World Health Organization (WHO) – Fact Sheet: Yellow Fever

WHO – International Health Regulations