english: (The first was yellow fever.)[33] John Burton Cleland and Joseph Franklin Siler kept studying the dengue virus, and figured out the basics of how the virus spreads.[33]
non_english: (Sadurungé para ilmuwan wis mbuktiake manawa virus uga kang njalari lelara kuning) [34] John Burton Cleland lan Joseph Franklin Siler terus neliti virus dengue, lan ngerti cara dhasar virus nyebar.[34]