BMW winner Jameka is being treated for travel sickness which will rule her out of a clash with Winx in Sydney and has cast a doubt on international plans.

Jameka was a dominant winner of the BMW (2400m) at Rosehill on Saturday to set up the prospect of the Queen Elizabeth Stakes against champion Winx at Randwick on April 8.

But on her return to trainer Ciaron Maher's Melbourne stable she was diagnosed with travel sickness, a build-up of fluid on the lungs.

Maher said he had had no experience with the illness before and it was caused by horses travelling with their heads up over a long period of time.

He said the illness was serious but vets had got to the problem early and treated it aggressively.

"The next couple of days will determine what she does in the coming weeks and months," Maher told RSN927.

"She's stable.

"Depending on how quickly she responds to some antibiotics and some fluids will hopefully mean she makes a speedy recovery.

"But at this stage it probably takes out the Queen Elizabeth."

Jameka was in line for a trip to Hong Kong to run in the QEII Cup on April 30 with the possibility of racing at Royal Ascot in June.

Maher says he has been told just because the mare has travel sickness she is no more likely than any other horse to get it again.