Cherries centre-back Cook had been ever-present in the Premier League this season before missing the last three games due to what was believed to be a minor problem.
But ahead of today’s trip to Huddersfield Town manager Eddie Howe has been dealt a major blow with news that the 27-year-old will be out until around mid-April.
“He had a long-standing groin problem, which we felt was quite minor,” said Howe.
“He had an injection on that area to try to fix the problem, that injection turned into an infection, so not good news regarding that and he’s going to be out for around five, six weeks.”
Bournemouth have endured a torrid run of injuries with Cook’s absence exacerbating the problem and leading Howe to select inexperienced defensive duo Chris Mepham and Jack Simpson in last weekend’s loss to Manchester City.
The Cherries have been without winger Junior Stanislas, top-scorer Callum Wilson and January signing Dominic Solanke in recent weeks, in addition to long-term absentees Simon Francis and Lewis Cook, while David Brooks returned from an ankle problem against league leaders City.
England international Wilson, who has hit 10 top-flight goals this season, has not featured since January 19 due to a knee issue, but could be in contention against the Terriers.
“He’s done some light training this week,” Howe said of Wilson. “He’s been back on the grass for the first time and has looked pretty good.
“We’ve got to pick and choose when the right moment is for him to come back.
“I’m going to have to consult with Callum and the physios to see how he feels.”
Mid-table Bournemouth, who are nine points above the bottom three, are without a win since the end of January, losing four of their five fixtures since.
Howe is keen to halt the slide and is hoping for a confidence-boosting victory as he seeks to make certain of safety.
“We’re absolutely desperate to do it and I think it’s important we do it quickly,” said Howe. “We want that momentum back in our performances, we want that confidence to return to the team.
“We recognise now that games are running out for us and we’re in a position where our safety isn’t secured and we’re losing distance with the teams above us.”
The Cherries have midfielder Jefferson Lerma back from a two-game ban today.