Yellow Fever
Transmission
Yellow fever is caused by a virus transmitted primarily by Aedes aegypti mosquitoes.

Yellow fever virus is an RNA virus that belongs to the genus Flavivirus. It is related to West Nile, St. Louis encephalitis, and Japanese encephalitis (JE) viruses.
Yellow fever virus is transmitted to people primarily through the bite of infected Aedes or Haemagogus species mosquitoes. Mosquitoes acquire the virus by feeding on infected primates (human or non-human) and then can transmit the virus to other primates (human or non-human). People infected with yellow fever virus are infectious to mosquitoes (referred to as being “viremic”) shortly before the onset of fever and up to 5 days after onset.
Yellow fever virus has three transmission cycles: jungle (sylvatic), intermediate (savannah), and urban.

Jungle (sylvatic) cycle → transmission of the virus between non-human primates (e.g., monkeys) and mosquito species found in the forest canopy. The virus is transmitted by mosquitoes from monkeys to humans when humans are visiting or working in the jungle.
Urban cycle → transmission of the virus between humans and urban mosquitoes, primarily Aedes aegypti. The virus is usually brought to the urban setting by a viremic human who was infected in the jungle or savannah.
Intermediate (Africa only) cycle → transmission of the virus from mosquitoes to humans living or working in jungle border areas. In this cycle, the virus can be transmitted from monkey to human or from human to human via mosquitoes.
Symptoms
Most people have no symptoms or mild symptoms and then recover. People who do develop symptoms usually do so 3 to 6 days after being bitten by an infected mosquito.
Initial symptoms include:
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Most people recover in about a week, though the weakness and fatigue sometimes last for several months.
⚠️ Some people develop more severe symptoms. These include:
high fever
jaundice
bleeding
shock
organ failure
About half of people who progress to this stage will die within 10 to 14 days. Yellow fever kills about 30,000 people every year worldwide.
Who is at Risk?
Yellow fever virus, and the mosquitoes that spread the virus, are found in certain parts of South America and Africa. Travellers going to these places are at risk for infection with the virus.
The Centers for Disease Control and Prevention (CDC) website includes a map indicating the risk of yellow fever transmission in different countries - here.
The following countries or areas^ are where the World Health Organization (WHO) has determined there is a risk of yellow fever transmission and/or where there are country requirements for travellers.
⚠️ The fact that a country does not demand a yellow fever certificate to enter, does not always mean that there is no risk of yellow fever in the country.
Country | Country determined by WHO to be at risk for yellow fever transmission2, 3 | Country requiring proof of vaccination against yellow fever for travellers4 arriving from | |
Countries determined by WHO to be at risk for yellow fever transmission2, 3 | Any country3 | ||
Albania | - | Yes (≥ 1 year) | - |
Algeria | - | Yes5 (≥ 9 months) | - |
Angola | Yes | - | Yes (≥ 9 months) |
Antigua and Barbuda | - | Yes5 (≥ 1 year) | - |
Argentina (Misiones and Corrientes Provinces) | Yes | - | - |
Aruba | - | Yes5 (≥ 9 months) | - |
Australia | - | Yes5, 7 (≥ 1 year) | - |
Bahamas (The) | - | Yes5 (≥ 1 year) | - |
Bahrain | - | Yes5 (≥ 9 months) | - |
Bangladesh | - | Yes8 (≥ 1 year) | - |
Barbados | - | Yes7 (≥ 1 year) | - |
Benin | Yes | - | Yes (≥ 9 months) |
Bolivia | Yes6 | Yes (≥ 1 year) | - |
Bonaire | - | Yes5 (≥ 9 months) | - |
Botswana | - | Yes8 (≥ 1 year) | - |
Brazil | Yes6 | - | - |
Brunei Darussalam | - | Yes5 (≥ 9 months) | - |
Burkina Faso | Yes | - | Yes (≥ 9 months) |
Burundi | Yes | - | Yes (≥ 9 months) |
Cabo Verde | - | Yes (≥ 1 year) | - |
Cambodia | - | Yes5 (≥ 1 year) | - |
Cameroon | Yes | - | Yes (≥ 1 year) |
Central African Republic | Yes | - | Yes (≥ 9 months) |
Chad | Yes6 | Yes (≥ 9 months) |
|
China | - | Yes5 (≥ 9 months) | - |
Christmas Island | - | Yes5, 7 (≥ 1 year) | - |
Colombia | Yes6 | Yes5, 7 (≥ 1 year) | - |
Congo | Yes | - | Yes (≥ 9 months) |
Costa Rica | - | Yes7 (≥ 9 months) | - |
Côte d’Ivoire | Yes | - | Yes (≥ 9 months) |
Cuba | - | Yes5 (≥ 9 months) | - |
Curacao | - | Yes5 (≥ 9 months) | - |
Democratic People’s Republic of Korea | - | Yes (≥ 1 year) | - |
Democratic Republic of the Congo | Yes | - | Yes (≥ 9 months) |
Djibouti | - | Yes5 (≥ 1 year) | - |
Dominica | - | Yes5 (≥ 1 year) | - |
Dominican Republic | - | Yes5, 7 (≥ 1 year) | - |
Ecuador | Yes6 | Yes5, 7 (≥ 1 year) | - |
Egypt | - | Yes5 (≥ 9 months) | - |
El Salvador | - | Yes5 (≥ 1 year) | - |
Equatorial Guinea | Yes | Yes (≥ 9 months) | - |
Eritrea | - | Yes (≥ 9 months) | - |
Eswatini | - | Yes8 (≥ 9 months) | - |
Ethiopia | Yes6 | Yes5 (≥ 9 months) | - |
Fiji | - | Yes5 (≥ 1 year) | - |
French Guiana | Yes | - | Yes (≥ 1 year) |
French Polynesia | - | Yes5 (≥ 1 year) | - |
Gabon | Yes | - | Yes (≥ 9 months) |
Gambia | Yes | Yes5 (≥ 9 months) | - |
Ghana | Yes | - | Yes (≥ 9 months) |
Grenada | - | Yes5 (≥ 1 year) | - |
Guadeloupe | - | Yes5 (≥ 1 year) | - |
Guatemala | - | Yes5 (≥ 1 year) | - |
Guinea | Yes | Yes (≥ 9 months) | - |
Guinea-Bissau | Yes | - | Yes (≥ 1 year) |
Guyana | Yes | Yes9 (≥ 1 year) | - |
Haiti | - | Yes (≥ 1 year) | - |
Honduras | - | Yes5 (≥ 1 year and ≤ 50 years) | - |
India | - | Yes7, 8 (≥ 9 months) | - |
Indonesia | - | Yes (≥ 9 months) | - |
Iran | - | Yes5 (≥ 9 months) | - |
Jamaica | - | Yes5 (≥ 1 year) | - |
Kazakhstan | - | Yes8 | - |
Kenya | Yes6 | Yes (≥ 1 year) | - |
Liberia | Yes | Yes (≥ 9 months) | - |
Madagascar | - | Yes5 (≥ 9 months) | - |
Malawi | - | Yes5 (≥ 1 year) | - |
Malaysia | - | Yes5 (≥ 1 year) | - |
Maldives | - | Yes5 (≥ 9 months) | - |
Mali | Yes6 | - | Yes (≥ 9 months) |
Malta | - | Yes5 (≥ 9 months) | - |
Martinique | - | Yes5 (≥ 1 year) | - |
Mauritania | Yes6 | Yes (≥ 1 year) | - |
Mayotte | - | Yes5 (≥ 1 year) | - |
Montserrat | - | Yes8 (≥ 1 year) | - |
Mozambique | - | Yes5 (≥ 1 year) | - |
Myanmar | - | Yes5 (≥ 1 year) | - |
Namibia | - | Yes5 (≥ 9 months) | - |
Nepal | - | Yes5 (≥ 9 months) | - |
New Caledonia | - | Yes (≥ 1 year) | - |
Nicaragua | - | Yes (≥ 1 year) | - |
Niger | Yes6 | - | Yes (≥ 9 months) |
Nigeria | Yes | Yes8 (≥ 9 months) | - |
Niue | - | Yes (≥ 9 months) | - |
Oman | - | Yes5, 7 (≥ 9 months) | - |
Pakistan | - | Yes5 (≥ 1 year) | - |
Panama | Yes6 | Yes (≥ 1 year) | - |
Papua New Guinea | - | Yes8 (≥ 1 year) | - |
Paraguay | Yes6 | Yes7, 10 (≥ 1 year) | - |
Peru | Yes6 | - | - |
Philippines | - | Yes5 (≥ 9 months) | - |
Pitcairn Islands | - | Yes (≥ 1 year) | - |
Qatar | - | Yes (≥ 9 months) | - |
Rwanda | - | Yes (≥ 1 year) | - |
Saint Barthelemy | - | Yes5 (≥ 1 year) | - |
Saint Helena | - | Yes (≥ 1 year) | - |
Saint Kitts and Nevis | - | Yes (≥ 1 year) | - |
Saint Lucia | - | Yes (≥ 9 months) | - |
Saint Martin | - | Yes5 (≥ 1 year) | - |
Saint Vincent and the Grenadines | - | Yes (≥ 1 year) | - |
Samoa | - | Yes5 (≥ 1 year) | - |
São Tomé and Príncipe | - | Yes8 (≥ 1 year) | - |
Saudi Arabia | - | Yes5 (≥ 9 months) | - |
Senegal | Yes | Yes8 (≥ 9 months) | - |
Seychelles | - | Yes8 (≥ 1 year) | - |
Sierra Leone | Yes | - | Yes |
Singapore | - | Yes5 (≥ 1 year) | - |
Sint Eustatius | - | Yes (≥ 6 months) | - |
Sint Maarten | - | Yes (≥ 9 months) | - |
Solomon Islands | - | Yes (≥ 9 months) | - |
South Africa | - | Yes5 (≥ 1 year) | - |
South Sudan | Yes | - | Yes (≥ 9 months) |
Sri Lanka | - | Yes5 (≥ 9 months) | - |
Sudan | Yes6 | - | - |
Suriname | Yes | Yes5 (≥ 1 year) | - |
Tanzania | - | Yes5 (≥ 1 year) | - |
Thailand | - | Yes5 (≥ 9 months) | - |
Togo | Yes | - | Yes (≥ 9 months) |
Trinidad and Tobago | Yes6 | - | - |
Uganda | Yes | - | Yes (≥ 1 year) |
^ Subject to change with or without notice. The WHO’s website should be checked for the most up-to-date information - here (search: yellow fever).
Prevention
Travellers can get the yellow fever vaccine and take steps to prevent mosquito bites.
⚕️ People planning to visit yellow fever-affected countries should seek advice from their doctor or a travel clinic at least 4-6 weeks before departing.
As noted above, some countries may require arriving travellers to show proof of yellow fever vaccination. Countries do this as a public health measure to keep travellers from importing the virus. Proof of vaccination requirements may apply to some or all arriving travellers.
Separate from the individual country requirements, the CDC makes yellow fever vaccine recommendations for travellers going to countries where there is a risk of yellow fever. CDC recommendations are designed to help keep individuals from getting infected with the yellow fever virus
More Information
Discover more about Yellow Fever at the following sites:
🇺🇸 United States - Center for Disease Control & Prevention (CDC)
🇳🇿 New Zealand - National Public Health Service (NPHS)
🇪🇺 European - Centre for Disease Prevention & Control
🇬🇧 United Kingdom - Travel Health Pro
🏴 United Kingdom (NHS Scotland) - Fit to Travel
🇨🇦 Canada - Public Health Services
🌐 World Health Organization (WHO)
General Travel Advice Disclaimer - here.