Yellow fever Health Article

Definition

Yellow fever is a viral infection transmitted by mosquitoes.

Causes, incidence, and risk factors

Yellow fever is caused by a small virus that is spread by the bite of mosquitoes. This disease is common in South America and in sub-Saharan Africa.

Anyone can get yellow fever, but the elderly have a higher risk of severe infection. If a person is bitten by an infected mosquito, symptoms usually develop 3 - 6 days later.

Yellow fever has three stages:

1. Early stage: Headache, muscle aches, fever, loss of appetite, vomiting, and jaundice are common. After approximately 3 - 4 days, often symptoms go away briefly (remission).
2. Period of remission: After 3 -4 days, fever and other symptoms go away. Most people will recover at this stage, but others may move onto the third, most dangerous stage (intoxication stage) within 24 hours.
3. Period of intoxication: Multi-organ dysfunction occurs. This includes liver and kidney failure, bleeding disorders/hemorrhage, brain dysfunction including delirium, seizures, coma, shock, and death.

Symptoms

• Arrhythmias, heart dysfunction
• Bleeding (may progress to hemorrhage)
• Coma
• Decreased urination
• Delirium
• Fever
• Headache
• Jaundice
• Muscle aches (myalgia)
• Red eyes, face, tongue
• Seizures
• Vomiting
• Vomiting blood

Signs and tests

A person with advanced yellow fever may show signs of liver failure, renal failure, and shock.

If you have symptoms of yellow fever, tell your doctor if you have traveled to areas where the disease is known to thrive. Blood tests can confirm the diagnosis.

Treatment

There is no specific treatment for yellow fever. Treatment for symptoms can include:

• Blood products for severe bleeding
• Dialysis for kidney failure
• Fluids through a vein (intravenous fluids)

Expectations (prognosis)

Yellow fever ranges in severity. Severe infections with internal bleeding and fever (hemorrhagic fever) are deadly in up to half of cases.

Complications

• Coma
• Death
• Disseminated intravascular coagulation (DIC)
• Kidney failure
• Liver failure
• Parotitis
• Secondary bacterial infections
• Shock

Calling your health care provider

Get medical attention at least 10 - 14 days before travelling to an endemic area for yellow fever to find out whether you should be vaccinated against the disease.

Tell your health care provider right away if you or your child develop fever, headache, muscle aches, vomiting, or jaundice, especially if you have traveled to an area where yellow fever is known to occur.

Prevention

If you will be traveling to an area where yellow fever is common:

• Sleep in screened housing
• Use mosquito repellents
• Wear clothing that fully covers your body

There is an effective vaccine against yellow fever. Ask your doctor at least 10 - 14 days before travelling if you should be vaccinated against yellow fever.

References

Bryan CS. Yellow fever in the Americas. Infect Dis Clin North Am. 2004; 18(2): 275-92.

Cohen J, Powderly WG. Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2004:2095-2098.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 6th ed. London: Churchill Livingstone; 2005.

Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001:1578-1580.