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Disease information

Virus or bacteria

Yellow fever is caused by yellow fever virus.

How it spreads

• Yellow fever spreads by the bite of a mosquito carrying the virus.
• It does not spread from person to person.

Yellow fever is not contagious. Someone with yellow fever cannot infect another person.

Symptoms

Initial phase:

• Fever, chills
• Headache
• Stiff neck or back
• Nausea, vomiting
• Fatigue, weakness

Of those who develop symptoms, a small number (about 14 of 100) will experience:

• Jaundice
• Dark urine
• Bleeding (mouth, nose, eyes, or stomach)
• Shock

Typical disease timeline

Mild symptoms can last for 0-4 days. Severe symptoms can begin during the initial phase and last up to 10 days.

Possible complications

• Organ failure
• About half of those who develop severe symptoms will die.

Other things to know

• Some countries require proof of yellow fever vaccination before entry.
• Each year, between 29,000 and 60,000 people die from yellow fever throughout the world.

Vaccine information 

The yellow fever vaccine is used to prevent yellow fever.

Vaccine type

• Live, “weakened” vaccines

Yellow fever vaccine side effects

Common

• Low-grade fever (25 of 100 recipients)
• Mild headache or muscle pain (25 of 100 recipients)
• Pain, swelling, or a lump at injection site (25 of 100 recipients)

Rare

• None

Very rare

• Severe allergic reaction (< 1 of 1,000,000 recipients)
• Life-threatening illness that resembles yellow fever (< 1 of 1,000,000 recipients)

Other things to know

• People with allergies to eggs or gelatin should talk to their doctor before receiving the yellow fever vaccine.
• Nursing or pregnant women, infants younger than 9 months of age, and adults 60 years or older should discuss vaccination with their doctor.
• The yellow fever vaccine is not routinely recommended in the U.S., but a certificate of vaccination is required for entry into some countries.
• Travelers should consult a travel clinic as only certain providers are authorized to give the yellow fever vaccine.

Reasons to get the yellow fever vaccine

• Most people who contract yellow fever don’t develop severe symptoms, but some do. Up to half of those who develop severe symptoms die from the infection.
• The yellow fever vaccine is safe.