Yellow Fever 1937 – Mosquito Vectors

Science writer Mary Crosby on yellow fever: 

"The virus attacks every organ, (and) the patient loses consciousness. The body hemorrhages, and blood flows from the eyes, nose, and mouth. Then the fever leaves its mark, turning the skin and the whites of the eyes bright yellow. It is this yellow color that gave the virus its name."

Several species of female mosquitoes, including Aedes aegypti, carry this virus, which is most commonly found in South America and Africa. Most cases involve fever and vomiting. However, 15% of cases enter a second phase with bleeding and jaundice, a yellowing of the skin caused by liver damage, which can be life-threatening. 

• In 1881, Cuban physician Carlos Finlay first proposed that mosquitoes could carry the yellow fever virus. 
• In 1900, United States Army surgeon Walter Reed began conducting experiments on humans to confirm this hypothesis. Yellow fever thus became the first virus shown to be carried by mosquitoes. 
• In 1937, South African-born virologist Max Theiler developed a live attenuated virus by growing it through many generations in chicken eggs, allowing it to lose its harmful properties while retaining its ability to replicate. This enabled the human immune system to develop a defense mechanism after vaccination. 
• In 1951, Max Theiler received the first Nobel Prize awarded for the development of a viral vaccine.

Yellow fever profoundly shaped the history of the United States. For example, in 1793, in Philadelphia (then the United States capital), a major epidemic forced George Washington and the United States administration to flee the city. Similarly, in 1802, yellow fever caused the deaths of many of Napoleon's soldiers in the Caribbean, leading him to abandon his claims to New Orleans and other United States territories and sell them to Thomas Jefferson at a low price. French plans to build the Panama Canal were thwarted by malaria and yellow fever.

Historical Figures Mentioned in This Article: Carlos Juan Finlay (1833–1915), Walter Reed (1851–1902), Max Theiler (1899–1972)

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