Yellow Fever



Yellow fever is a viral disease.


An infected mosquito passes the virus to you through a bite on your skin.

Mosquito Bite
Mosquito bite
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Risk Factors

Your risk may be higher if you:

  • Live, work, or travel to regions where yellow fever is common
  • Do not take preventive steps such as getting a vaccine or protecting yourself against mosquitoes



Symptoms appear within a week after a mosquito bite. The acute phase lasts 3-4 days, then symptoms go away. Some people progress to the toxic phase. This starts within 24 hours of the end of the first phase. Recovery will provide lifetime protection against yellow fever.

Some people may not have symptoms. If they appear, they may include:

Acute phase:

  • Fever
  • Headache
  • Muscle pain
  • Backache
  • Chills
  • Loss of appetite
  • Nausea or vomiting

Toxic phase:

  • High fever
  • Belly pain
  • Bleeding from the gums, nose, eyes, or stomach
  • Vomit that appears black (caused by bleeding)
  • Yellowing of the skin— jaundice
  • Confusion
  • Seizure
  • Coma


Your doctor will ask about your symptoms, and health and travel history. You will also have:

  • A physical exam
  • Blood tests to detect antibodies



Care may start in a hospital. There are no medicines to treat yellow fever. The goal of care is to ease symptoms. Care may include:

  • Fluids by mouth or through an IV to prevent dehydration
  • Medicines to lower your fever
  • Dialysis (toxic phase) to help your kidneys filter waste
  • Transfusion (toxic phase) to replace blood products lost through bleeding
Dialysis pump
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If you live in or are traveling to an area where yellow fever is common, talk to your doctor about getting the vaccine .

In addition:

  • Stay in places with screens or air conditioning.
  • Cover your skin with long clothes, socks, and shoes.
  • Use bug sprays that contain DEET.
  • Use mosquito netting treated with bug spray.
  • Keep in mind mosquitoes are more active during early morning, late afternoon, and early evening.
  • Tip out standing water in buckets, flower pots, or other containers. Mosquitoes breed in standing water.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.


Centers for Disease Control and Prevention 

World Health Organization 


Public Health Agency of Canada 

Travel Health and Safety 


García-Rejón JE, Loroño-Pino MA, Farfán-Ale JA, et al. Mosquito infestation and dengue virus infection in Aedes aegypti females in schools in Merida, Mexico. Am J Trop Med Hyg. 2011;84(3):489-496.

Walker KR, Joy TK, Ellers-Kirk C, Ramberg FB. Human and environmental factors affecting Aedes aegypti distribution in an arid urban environment. J Am Mosq Control Assoc. 2011;27(2):135-141.

Yellow fever. Centers for Disease Control and Prevention website. Available at: Updated March 27, 2018. Accessed May 11, 2018.

Yellow fever. EBSCO DynaMed Plus website. Available at:  . Updated May 7, 2018. Accessed May 11, 2018.

Yellow fever VIS. Centers for Disease Control and Prevention website. Available at: Updated October 18, 2016. Accessed May 11, 2018.