Yellow fever

Yellow fever is a viral disease transmitted between humans by mosquitoes. The disease occurs only in parts of Africa and South America.


Symptoms of the disease range from fever, chills, and headache to abdominal pain, vomiting, and jaundice. There may appear to be a brief recovery before the disease progresses to more severe complications including internal bleeding, and kidney or liver failure. Death occurs in about 5% of those infected. There is no medical treatment apart from keeping the fever down and avoiding dehydration.

Endemic yellow fever areas

There are countries in Africa and South America that have endemic yellow fever .

In South America, the "endemic yellow fever zone" includes: Panama, Columbia, Venezuela, Guyana, Suriname, French Guiana, western Ecuador, western Peru, western Bolivia, eastern Brazil.

In these countries sporadic infections occur almost exclusively to forestry and agricultural workers who are exposed occupationally in or near forests.

In Africa, the "endemic yellow fever zone" includes: Angola, Tanzania, Zaire, Kenya, Uganda, Somalia, Ethiopia, southern Sudan, southern Sudan, southern Chad, southern Niger, southern Mali, Central African Republic, Congo, Gabon, Rio Muni, Cameroon, Nigeria, Benin, Togo, Ghana, Burkino Faso, Ivary Coast, Liberia, Sierra Leone, Guinea, Guinea-Bissau, Gambia, Senegal, Sao Tome and Principe Islands.

In Africa the virus is transmitted in three geographic regions: principally and foremost, in the moist savanna zones of West and Central Africa during the rainy season, secondly, outbreaks occur occasionally in urban locations and villages in Africa, and finally, to a lesser extent, in jungle regions.


General precautions to avoid mosquito bites should be followed. These include the use of insect repellent, protective clothing, and mosquito netting. These mosquitoes bite mainly during the evening and morning hours.

Yellow fever certificate requirement

Although yellow fever is a very rare cause of illness in travelers, most countries require a certificate from travelers arriving from infected areas. Some countries in Africa require evidence of vaccination from all entering travelers. Vaccination is also recommended for travel outside the urban areas of countries which do not officially report the disease, but which lie in the yellow fever endemic zone. Some countries require an individual, even only in transit, to have a valid International Certificate of Vaccination if he or she has been in countries either known or thought to harbor Yellow Fever virus. Such requirements may be strictly enforced, particularly for persons traveling from Africa or South America to Asia.

Yellow fever vaccination certificate

Yellow fever vaccine is a live virus vaccine. A single dose confers long-lived immunity lasting 10 years or more. This vaccine has been used for several decades and has a very low rate of adverse reactions associated with it. After immunization an International Certificate of Vaccination is issued and is valid 10 days after vaccination to meet entry and exit requirements for all countries. The Certificate is good for 10 years. You must take the Certificate with you.

One dose of yellow fever vaccine may be administered to adults and children over 9 months of age. This vaccine is only administered at designated yellow fever centers, usually your local health department. Consult your local health department for yellow fever vaccination sites near you. If at continued risk of yellow fever infection, a booster dose is needed every 10 years.

Medical waiver

Travelers who have a medical reason not to receive the yellow fever vaccine should obtain a medical waiver. Most countries will accept a medical waiver for persons with a medical reason not to receive the vaccine (e.g. infants less than 4 months old, pregnant women, persons hypersensitive to eggs, or those with an immunosuppressed condition.) In such cases, obtain the waiver in writing from consular or embassy officials before departure. A physician's letter clearly stating the medical reason not to receive the vaccine might be acceptable to some governments. It should be written on letterhead stationery and bear the stamp used by a health department or official immunization center to validate the International Certificate of Vaccination. Check embassies or consulates for specific waiver requirements.