1:515-30Africa, Middle East, Turkey, Balkans, southern region of former Soviet Union, western ChinaAll ages, both sexes: men more exposed in some settingsYellow fever3-61:2-1:2020Africa, South AmericaAh ages, both sexes; adults more exposed in jungle setting; preexisting flavivirus immunity may cross-protectDengue HF/dengue shock syndrome2-7Nonimmune, 1:10,000; heterologous immune, 1:100">