He was later discovered to be seriously ill.

后来才了解到他患了重病。

《牛津词典》

She became seriously ill and had to be institutionalized for a lengthy period.

她病情严重，不得不被长期收容治疗。

《柯林斯英汉双解大词典》

Whether Dr Georgopoulos's technique can distinguish those who will become seriously ill from those who will not remains to be seen.

乔治欧·普罗斯博士的技术是否能区分那些没恶化的和恶化的病人我们将拭目以待。

youdao

But a German woman is reported by doctors to be seriously ill.

ECONOMIST: The Philippines: Muddling on, but not through | The

The ASA says it doesn't wish to "disregard anyone's beliefs, but specific claims targeted at people who may be seriously ill must comply with the rules on substantiation and social responsibility that apply to all other advertising".

BBC: Divine healing advertisement controversy

Pistons coach Lawrence Frank returned after missing six games to be with his seriously ill wife.

WSJ: Nets crush Pistons to open 8-game road trip