Yellow Fever

Countries with risk of yellow fever virus transmission

Africa

Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Republic of the Côte d’Ivoire, Democratic Republic of the Congo and Equatorial Guinea, Ethiopia, Gabon, The Gambia Ghana, Guinea, Guinea-Bissau Kenya, Liberia, Mali, Mauritania, Niger, Nigeria Senegal, Sierra Leone, South Sudan Sudan, Togo Uganda

Central and South America

Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela

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Countries with low potential for exposure to yellow fever virus:

Eritrea, Rwanda, São Tomé and Príncipe Somalia Tanzania, Zambia

 

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Risk for Travelers

A traveler’s risk for acquiring YF is determined by various factors, including immunization status, location of travel, season, duration of exposure, occupational and recreational activities while traveling, and local rate of virus transmission at the time of travel. Although reported cases of human disease are the principal indicator of disease risk, case reports may be absent because of a low level of transmission, a high level of immunity in the population (because of vaccination, for example), or failure of local surveillance systems to detect cases. Since “epidemiological silence” does not mean absence of risk, travelers should not go into endemic areas without taking protective measures.

YF virus transmission in rural West Africa is seasonal, with an elevated risk during the end of the rainy season and the beginning of the dry season (usually July–October). However, Ae. aegypti may transmit YF virus episodically, even during the dry season, in both rural and densely settled urban areas.

 

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Yellow fever symptoms

Most people infected with YF virus likely do not seek medical attention because they have minimal or no symptoms. The initial illness is nonspecific: fever, chills, headache, backache, myalgia, prostration, nausea, and vomiting. Most patients improve after the initial presentation. After a brief remission of up to 24 hours, approximately 12% of those infected progress to a more serious form of the disease, characterized by jaundice, hemorrhagic symptoms, and eventually shock and multi-system organ failure. The case-fatality ratio for severe cases is 30%–60%.

 

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Treatment

There are no specific medications to treat YF virus infections; treatment is directed at symptomatic relief or life-saving interventions. Rest, fluids, and use of analgesics and antipyretics may relieve symptoms of aching and fever.

 

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Prevention

Personal Protection Measures. The best way to prevent mosquito borne diseases, including YF, is to avoid mosquito bites

 

 

Vaccine

YF can be prevented by a relatively safe, effective vaccine. All YF vaccines currently manufactured are live attenuated viral vaccines. YF vaccine is recommended for people aged ≥9 months who are traveling to or living in areas with risk for YF virus transmission in South America and Africa. In addition, some countries require proof of YF vaccination for entry.

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Because of the risk of serious adverse events after YF vaccination, clinicians should only vaccinate people who are at risk of exposure to YF virus or who require proof of vaccination to enter a country. To minimize further the risk of serious adverse events, clinicians should carefully observe the contraindications and consider the precautions to vaccination before administering YF vaccine

 

Additional Information: CDC Health Information for International Travel 2020, Yellow Fever, p. 377-390.