Geography: Africa, Central and South America
Cases Per Year: approximately 200,000
Fatality Rate: 3% to 8%
First Discovered: 1647 in Barbados; Josiah C. Nott, Carlos Finlay, and Walter Reed discovered its transmission pattern in the mid-late 1800s
Yellow fever is spread to people by the bite of an infected mosquito. Mosquitos acquire the virus by feeding on infected primates (including humans) and transmit it to other primates. It is endemic in 33 countries in tropical areas. The time from infection until symptoms appear is typically 3 to 6 days. Symptoms include fever, headache, muscle pain, nausea, vomiting, fatigue, and liver disease with bleeding and jaundice (yellow skin). A small percentage of people who contract the virus develop severe symptoms, and approximately half of them die within 7 to 10 days. There is no medicine to treat or cure yellow fever, so it is important to prevent infection by using insect repellent, wearing long-sleeved shirts and long pants, and getting vaccinated.
There are three transmission cycles of yellow fever: jungle, intermediate (savannah), and urban.
Photo: A Flavivirus – Electron micrograph