Yellow fever is a serious viral infection transmitted by mosquitoes. It occurs mostly in Africa and South America.

Symptoms of yellow fever usually appear suddenly and may include:

• Fever.
• Headache.
• Slow heartbeat.
• Yellowish skin (jaundice).
• Vomiting.
• Bleeding from the mucous membranes of the nose and mouth. Gastrointestinal bleeding may cause the person to vomit blood.

There is no specific treatment for yellow fever. Many cases of yellow fever are mild, and people recover completely within a few days to a week. More severe cases may lead to serious bleeding, failure of the heart, liver, or kidneys, and death within a week to 10 days.