They develop a fever and a watery discharge from their eyes.

他们开始发烧，且有一种水状分泌物从他们的眼睛里流出。

《柯林斯英汉双解大词典》

And in up to half of all cases, people never develop a fever.

而且在目前的已知病例中，有一半从来都没有发烧的症状。

youdao

Up to half the people who get swine flu never develop a fever, and some suffer from gastrointestinal.

有多达一半的猪流感患者并不发烧，而有些人除了常规的流感症状还出现了胃肠症状。

youdao