Western Force coach Richard Graham has ruled out the need to place any of his Super Rugby players in quarantine, saying the virus that swept through his backline last week hadn't shown any signs of resurfacing.

Nick Cummins, Gene Fairbanks, Alfie Mafi and Pat Dellit were all violently ill on the eve of last Saturday's 51-16 loss to the Stormers in Cape Town, with the quartet spending Friday and Saturday nights on a drip.

Cummins spent most of Friday night vomiting but, along with Dellit and Mafi, still managed to play against the Stormers, with only Fairbanks unable to take his spot.

The Force take on the unpredictable Melbourne Rebels in Perth on Saturday night and Graham was confident the mystery virus wouldn't spread.

"It hasn't affected the rest of the group," Graham said after landing at Perth airport on Monday afternoon.

"It was isolated to four people so ... we'll just get on with it.

"Those that were ill have been on drips.

"We monitored them yesterday before we got on the plane.

"The doctor's here with them today.

"We'll go home and recover and train again on Wednesday."

Force flanker Matt Hodgson had one theory as to why the virus only struck certain players.

"I think the forwards have a lot stronger stomachs than the backs," Hodgson joked.

"Backs hang out with backs so they must have all done something together at one time during the tour that got them crook.

"If you eat or drink something wrong it can happen to anyone."

Graham will closely monitor his backline over the coming days before deciding whether any of his recovering charges need to be rested against Melbourne.

The Force will at least have a few more options up their sleeve this weekend, with five-eighth Willie Ripia expected to prove his fitness after overcoming a nagging foot injury and utility back Rory Sidey available after serving his suspension.

James O'Connor has dazzled at five-eighth this season, but Ripia's return could see the star Wallaby shifted to either the wing or inside centre.

Graham was hopeful Ripia would be ready for action after a frustrating stint on the sidelines.

"(He is) running well. His strength level's back to where they were in pre-season," Graham said.

"I'll just need to see him at training on Wednesday to see how he handles the ball and also his work under pressure."

Meanwhile, prop Tim Fairbrother will leave the Force at the end of the season after accepting a deal to play for English side Harlequins next year.

New Zealand-born Fairbrother was eligible to play for the Wallabies due to his Australian-born grandparents, but his inability to break into the national set-up convinced him it was time to move on.

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