Cheryl Cole is in hospital, being treated for malaria, her spokesman has confirmed.
The X Factor judge remains in London's private Cromwell Hospital, where her close friend Derek Hough has been at her bedside.
The 27-year-old contracted the disease on her trip to Tanzania with the US dancer and was diagnosed despite taking malaria tablets.
She and Hough spent six days together on Africa's east coast last month following her split from England footballer Ashley.
The singer is reported to have collapsed dramatically with suspected gastroenteritis during a photoshoot for her album on Saturday afternoon, when she was initially diagnosed with exhaustion.
But she was rushed to hospital the next day after her symptoms, including a soaring fever, dramatically worsened.
Cole, who has been filming the audition stage of ITV talent show The X Factor, has now pulled out of work commitments for the coming days on the advice of doctors.
If not treated promptly, malaria can become life-threatening by disrupting the blood supply to vital organs.
It is caused by the parasite plasmodium, which is transmitted by the bites of infected mosquitos. Symptoms include headaches, fever and vomiting.
Cole, who has been supporting Black Eyed Peas on tour and is scheduled to play high-profile shows at next month's V Festival, also visited east Africa last year when she climbed Mount Kilimanjaro for Comic Relief.
Her spokesman said: "Cheryl Cole is currently in hospital, being treated for malaria.
"Following doctors' advice she will be cancelling all work commitments for the next week."
An X Factor spokesman was unavailable for comment.