Yellow fever is caused by an arbovirus, a small virus transmitted by the bite of mosquitoes. This disease is common in South America and in sub-Saharan Africa. Humans and monkeys are both hosts in the transmission cycle of this infection.

While yellow fever can affect individuals of all ages, the elderly have a higher risk of severe infection. If a person is bitten by an infected mosquito, symptoms usually develop three to six 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.
2. Period of remission: fever and other symptoms resolve -- most individuals will recover at this stage, yet up to 15% may move onto the third, most dangerous stage.
3. Period of intoxication: characterized by multi-organ dysfunction -- liver and kidney failure, bleeding disorders/hemorrhage, brain dysfunction including delirium, seizures, coma, shock, and in up to 30% individuals, death.

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

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 health care provider 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.

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

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 endemic area for yellow fever.

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. Notify your health care provider at least 10-14 days prior to travel to determine whether you should be vaccinated against yellow fever.