Yellow fever is an acute viral infection caused by the yellow fever virus. Primates are the main reservoir of the virus, which is usually transmitted through bites from infected mosquitoes. Yellow fever is endemic in large parts of South America and Africa. The incubation period is 3–6 days, and the majority of affected individuals remain asymptomatic or experience only mild symptoms. Symptomatic patients initially present with nonspecific symptoms such as sudden-onset fever, malaise, headaches, chills, nausea, and myalgia. Approx. 15% of these patients progress to the most serious stage of the disease, which can present with life-threatening hemorrhagic fever and organ failure. There is no causal treatment available, making prevention of crucial importance. A single dose of live-attenuated vaccine provides lifelong protection for most individuals.
- Yellow fever is endemic in tropical regions of South America and Sub-Saharan Africa.
- Asia, Europe, North America, and Australia are free of yellow fever (except for occasional imported cases).
Epidemiological data refers to the US, unless otherwise specified.
- Pathogen: yellow fever virus
- Incubation time: 3–6 days
- The majority of infected individuals remain asymptomatic.
In symptomatic patients: classic progression in three stages
- Period of infection (3–4 days)
Period of remission (up to 2 days)
- Easing of symptoms and decline in fever
- Period of intoxication (only in ∼ 15% of symptomatic patients)
Most patients remain asymptomatic or experience only mild symptoms.
- Laboratory tests
- Virus detection
- Liver biopsy
- The yellow fever vaccine is a live-attenuated vaccine administered subcutaneously.
- Indications: individuals 9 months to 60 years of age ≥ 10 days prior to 
- A single lifetime dose is typically sufficient; some individuals may require a booster. 
- Contraindications include: 
When contraindications are present, consider the individual's specific risks and benefits and use shared-decision making to decide whether to immunize.
If state supplies of yellow fever vaccine are limited, direct international travelers to the following CDC website (wwwnc.cdc.gov/travel/page/search-for-stamaril-clinics) for US providers of imported, non-FDA approved yellow fever vaccines.