1) A disease carried by mosquitoes in tropical regions, especially in South America, Africa, and the Caribbean. Symptoms include sudden fever, yellowing of the skin, and hemorrhaging. A very dangerous disease that is quite often fatal. It was the number one cause of death for Americans during the construction of the Panama Canal. Nowadays a yellow fever vaccine is required if you're traveling to said tropical regions, especially during the summer.
2) When a person of non-Asian ethnicity has strong feelings and/or urges of an Asian person of the opposite gender. Usually these urges are sexual, but not always. Wasn't too widely known until the release of Harold and Kumar Go to White Castle