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Yellow fever

Definition

Yellow fever is a viral infection transmitted by mosquitoes that causes fever, jaundice, kidney failure, and bleeding.

Causes

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 to 6 days later.

Yellow fever can be divided into three stages:

1. Early stage: Headache, muscle aches, fever, loss of appetite, vomiting, and jaundice are common. After approximately 3 to 4 days, victims often experience brief remission.
2. Period of remission: After a few days (3 to 4) fever and other symptoms go away. Most individuals 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

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

Exams and Tests

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

If you have symptoms of yellow fever, tell your doctor if you have traveled to areas where the disease is known to thrive. The diagnosis is confirmed by blood tests that reveal the virus, viral antigens, or antibodies.

Treatment

There is no specific treatment for yellow fever. Treatment for symptoms may include intravenous fluids, blood products for severe bleeding, and dialysis for renal failure.

Outlook (Prognosis)

Yellow fever ranges in severity. Severe infections with internal bleeding and fever (hemorrhagic fever) are deadly in 25 - 50% of cases.

Possible Complications

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

When to Contact a Medical Professional

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

Notify 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, use mosquito repellents, wear clothing that fully covers your body, and sleep in screened housing. There is an effective vaccine against yellow fever. Ask your doctor at least 10-14 days prior to travel if you should be vaccinated against yellow fever.

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. 5th ed. London: Churchill Livingstone; 2000:1726.

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