Cheryl Cole has contracted the potentially deadly disease malaria.
She caught the disease on a trip to Tanzania with her dancer friend Derek Hough.
The X Factor went to Africa's East coast along with her pal in a bid to rejuvenate herself.
After collapsing with suspected gastroenteritis during the photo shoot for her album, the 27-year-old was advised rest, but began drifting in and out of consciousness and was rushed to a Surrey hospital, where doctors diagnosed malaria.
Cheryl's spokesman has also confirmed that she is suffering from malaria.
A source close to the star has revealed that Cheryl would be kept in hospital for another night and could remain under close observation for up to two weeks. Her involvement in the rest of this series of The X Factor is in serious doubt.
"She told doctors she'd had stomach pains since her return from Tanzania. On Sunday evening her condition deteriorated so rapidly she knew it was something serious," the Sun quoted the source as saying.
"She'd spent 48 hours in bed trying to sleep off what she thought was a stomach bug. She was extremely weak, sweating and drifting in and out of consciousness. She was driven to hospital where tests showed malaria. Everyone is really concerned. She is very ill," the source added.
X Factor mogul Simon Cowell texted Cheryl and told her, "Have some rest. Don't rush back."
