english: (Scientists had already proven that a virus causes yellow fever.)[34] John Burton Cleland and Joseph Franklin Siler kept studying the dengue virus, and figured out the basics of hoe the virus spreads.[34]
non_english: (Sak durunge para ilmuwan wis mbuktiake manawa virus uga sing nyebabake lelara kuning) [34] John Burton Cleland lan Joseph Franklin Siler terus neliti virus dengue, lan ngerti cara dasar virus nyebar.[34]