Yellow Fever Definition-A tropical viral disease affecting the liver and kidneys, causing fever and jaundice and often fatal. It is transmitted by mosquitoes. Yellow fever also known as yellow jack, black vomit, or “vomito negro” in Spanish was named by a scientist Walter Reed in Havana City, Cuba where a U.S. Army yellow fever commission led by Walter Reed proved that yellow fever was a viral disease transmitted by a specific mosquito named Aedes aegypti.