The patient has contracted a fatal illness. There is little chance of his recovery.

这个病人已病入膏肓， 没有多少痊愈的希望了。

《新英汉大辞典》

Data continue to show that certain medical conditions increase the risk of severe and fatal illness.

数据继续显示，某些病症会加大严重和致命疾病的风险。

youdao

This is true for those most frequently infected, and especially so for those experiencing severe or fatal illness.

对感染最多的人群是这样，尤其是对出现严重或致命疾病的人群。

youdao

At Sydney's Royal North Shore hospital a video linkup has allowed doctors from Vietnam and Japan to present case studies and to share their experiences in dealing with a potentially fatal illness.

VOA: standard.2009.08.25

She was SUFFERING from a FATAL ILLNESS for, at the very lease, the last five years of her life.

FORBES: Winehouse Death Renews Debate About Addiction and Choice

Hospice deploys nurses, doctors, and social workers to help people with a fatal illness have the fullest possible lives right now.

NEWYORKER: Letting Go

But they add that "the known facts of Mozart's fatal illness, including the features of oedema, malaise and back pain, seem compatible with this diagnosis".

BBC: Mozart 'killed by strep throat'