Parents distraught over baby's mystery illness

A little Perth boy has been struck down by a mystery illness that causes up to 50 seizures a day, and doctors aren't sure why it's happening.

Zavier Elward's devastated parents are desperate for answers.

Their baby boy was born perfectly healthy, but at around six months old something changed.

"He was doing these really weird movements, like just looking up into the distance and his mouth was slowly twitching, sort of like he was smiling," mum Shaileen Roberts said.

Zavier's parents took him to hospital, but his condition deteriorated. He stopped breathing and soon began having up to 50 seizures a day, some lasting up to seven minutes.

Zavier was pumped with steroids, and at eight months old he weighed 17 kg - a healthy baby usually weighs half that amount.

Doctors initially diagnosed him with the extremely rare West Syndrome, which causes cluster seizures.

But it usually subsides in a few months, and Zavier's seizures haven't. Doctors at Princess Margaret Hospital still don't know why.

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"They don't know what it is, they're just trial and error on the medications, just to see what works and what doesn't," Zavier's dad Harley said.

In the meantime, medications and intensive therapy are costing $1500 a fortnight and the family is struggling.

A GoFundMe page has been set up to help relieve the financial stress.

"We want to see him walking, talking, playing with other kids," Harley said.

"Just normal kid things."

"We could have lost him," Shaileen said.

"It's not fair to go through what we're going through.