Yellow Fever Facts and History
- Yellow fever is a viral hemorrhagic infection transmitted by mosquitoes of the Aedes genus.
- Yellow fever has and continues to affect the equatorial tropics and is believed to have been imported to the Americas with the West African slave trade. As early as the 1600s, the Mayans recorded a yellow fever epidemic in the Yucatan and Guadalupe. Throughout the next 200 years, yellow fever epidemics plagued the tropics and coasts of the Americas and Caribbean. The first major yellow fever epidemic struck the U.S. in Philadelphia in July 1793. At the time, Philadelphia was home to over 2,000 free blacks, and white refugees where fleeing from Santo Domingo colony in the Caribbean after a slave uprising. By the end of the epidemic in the winter, of a population of 45,000, 5,000 had died and 17,000 left the city.
- Benjamin Rush, one of the original signers of the Declaration of Independence, gained renown as a physician who tirelessly offered heroic treatments, including mercury and bloodletting, during the epidemic. At the time, yellow fever was not well understood to be a contagion, and one of his efforts to enlist blacks to care for the sick failed, because he mistakenly believed them to be immune.
- In contradiction to the then prevalent view of disease spreading by "bad air" or rotting materials, American physician Josiah Clark Nott in 1848 and Cuban physician Carlos Finlay in 1881 proposed that a vector was spreading yellow fever. Dr. Finlay is remembered for his pioneering work to identify the Aedes mosquito as the vector of yellow fever, and he first proposed mosquito control to control the spread of yellow fever.
- Yellow fever hindered American efforts during the 1898 Spanish American War, killing more infantry than the fighting, and completion of the Panama Canal was nearly halted as 10% of workers died. The U.S. Army established the Yellow Fever Commission in Cuba to study the problem, and Army physician Major General Walter Reed, experienced in the study of tropical diseases, was appointed head. Crediting and building on Finlay's work, his experiments proved that yellow fever was spread by the bite of the Aedes mosquito. From this point, mosquito-control measures permitted completion of the Panama Canal in 1903.
- Up to 50% of severely affected people will die from yellow fever without treatment.
- The World Health Organization estimates that 200,000 cases of yellow fever occur globally every year, causing 30,000 deaths. Yellow fever is very common to the tropics of Latin America and Africa, and 90% of cases occur in Africa.
- Yellow fever cases are rising since the 1990s because of multiple factors, including declining population antibodies, urbanization and human encroachment into wilderness, and expanding mosquito habitats due to global warming and climate change.
- One of the hallmarks that gives yellow fever its name is jaundice, or yellowing of the skin and sclerae in more severe disease. Eighty-five percent of cases of yellow fever present as a flu-like illness, with fevers, chills, headache, backache, and nausea and vomiting. Serious illness arises in 15% of those infected within 24 hours after initial resolution. High fever, abdominal pain, nausea and vomiting, and jaundice occur, progressing to typical "hemorrhagic fever" with kidney failure and bloody stools, bleeding from orifices, and vomiting ("black vomit"). Half of victims with the hemorrhagic fever stage recover, and half die within 14 days.
- Treatment is directed at reducing the symptoms until the illness completes its course. There is no specific treatment for yellow fever. Because the illness may be very similar to malaria, hepatitis, leptospirosis, and other viral hemorrhagic fevers that may also exist in the geographic area, it can only be definitively diagnosed by specialized antibody testing or postmortem. Yellow fever vaccine is a major prevention tool, and one dose provides lifelong protection against yellow fever for people who live in endemic areas. Some travelers have contraindications to yellow fever vaccine that outweigh the benefit of the vaccine. In addition, some countries require proof of yellow fever vaccination in travelers arriving from endemic areas, even if only stopping to connect to another flight.
Medically Reviewed by a Doctor on 6/19/2015
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