England will be without Andy Farrell, James Simpson-Daniel, Mike Brown and Andy Hazell for the second Test against South Africa on Saturday.
Farrell, Simpson-Daniel and Brown are unavailable because of the stomach virus which has hit the squad, while Hazell has a knee injury.
England coach Brian Ashton, who expects Jason Robinson to be fit, has delayed naming his team until Friday lunchtime.
He has also called up uncapped 20-year-old Bath back Nick Abendanon.
Robinson, who captained the team in the first Test, is battling to overcome fluid on the knee.
"He's been undergoing rehabilitation this week and spent the morning in the gym and in the pool," said Ashton. "We're confident he'll be OK to take his place in the team on Friday."
England are tipped to make changes to their pack for the match, with prop Matt Stevens and lock Roy Winters expected to feature in the starting line-up.
"I am not making any excuses before the game - I am just reporting the facts"
Ashton said Abendanon, who scored a try and was man of the match as England's second-string Saxons side beat Scotland A 18-3 on Monday, could go straight into the 22-man squad for Saturday.
"It's disappointing that so many of the guys have been injured or ill but I was over the moon when I heard," said Abendanon, who was born in South Africa and moved to England as a child.
"I was pretty shocked but obviously very pleased. All my family live in Johannesburg so it will be great to have some support in Pretoria and I just hope I will be involved in some way."
England flew into South Africa missing about 35 first-choice players because of a combination of club commitments and injury, and they have lost David Strettle, Nick Wood and Iain Balshaw since arriving.
606: DEBATE
Ashton said Brown, Simpson-Daniel and Farrell are currently too ill to fly home because of the effects of the stomach bug.
He added: "We thought that Mike Brown and James Simpson-Daniel had recovered yesterday, but that is not the case.
"I don't really know what to say. It doesn't seem this bug will leave the camp, but I am not making any excuses before the game - I am just reporting the facts."
South Africa recorded their record win against England when they hammered them 58-10 in the first Test on Saturday.
And when Ashton was asked if he felt any sympathy for Springbok coach Jake White, who has had to deal with players going down with the flu this week, the England coach replied emphatically "no".