A knock to the head that left apprentice jockey Tahlia Hope with undiagnosed swelling and a bleed to the brain may have contributed to her contracting viral meningitis.

Hope spent 12 days in hospital and remains on a drip at her parents home after falling ill three weeks ago.

She said doctors could not pinpoint what caused her to become so sick, adding they weren't happy when they discovered Hope had concussion and had failed to undergo a head-scan.

“Doctors haven't been able to put it altogether, it's a little bit of everything,” Hope told RSN927.

“I had a concussion a month and a bit before and I was quite rundown at the time as well.

“They're not one hundred per cent sure what brought it on and why I got it so bad.”

Hope said she was concussed after a horse flipped in the barriers and she landed on her head and somersaulted.

After a poor night's sleep, Hope became unwell and was stood down from riding because of concussion before passing a test and getting back in the saddle and riding winners.

But it turned sour on July 10 when she woke up with a headache and began vomiting, forcing her to miss trackwork, jumpouts and racing at Sandown.

She spent the next 12 days in hospital, not remembering the first couple of days as doctors worked to get her better.

A blood test taken on Tuesday will determine whether Hope comes off the drip on Thursday, although a return to the saddle is still a while off.

“I've got to go back in five weeks to get another lot of tests done and get a head scan to see if the swelling and bleed has finally gone,” Hope said.

“But I haven't decided if I'll come back straight away or take a little break.”