Cricket World Cup 2011: England's Andrew Strauss and Graeme Swann hit by stomach upset ahead of West Indies

Tummy troubles: England captain Andrew Strauss (left) has been hit

Their participation in Thursday's must-win World Cup Group B match against West Indies is, however, not thought to be in doubt at this stage.

England can ill afford any injury or illness-enforced absences to anyone for a fixture which is almost certain to determine whether they reach the knockout stages.

Strauss and Swann are two of their most influential personnel, but an England spokesman indicated they are expected to be recovered by tomorrow - and certainly in time to face the Windies.

Similar hopes were dashed earlier in this tournament, though, when Stuart Broad - who later had to fly home because of a side strain - had to miss England's defeat against Ireland because of tummy trouble in Bangalore.

Swann, meanwhile, insists there is plenty of one-day international mileage left in Strauss' England, irrespective of whether their World Cup campaign comes to an abrupt end this week.

"I hope it's not a watershed, because that normally means the older players get the boot - and I'm one of them," he said.

"I haven't spoken to Straussy [about his retirement]. He's certainly made no overtures about resignation to any of the team. I'd be very surprised if that was the case."

England are in grave danger of another early World Cup exit, and must beat West Indies in Chennai on Thursday to reach the knockout stages for the first time since 1996.

Even if they fall short, though, Swann has great hopes for the longer-term future.

"We're obviously still developing, because we're not world champions," he said.

"If we'd won three World Cups and were trouncing everyone we play, we could probably say we're not developing as a side."

He is optimistic, in any case, that England can rescue their campaign against the Windies.

"We play our best cricket when we've got our backs against the wall," he said.

"We've proven that over the last couple of years. When we go one up in a Test series we tend to have a stinker before pulling out all the stops to play our best cricket.

"It's been the same in one-day cricket and it's something we have to do now - otherwise, we're back home."