Doctors at Wollongong Hospital couldn't work out what was wrong with Evangeline Doosey-Shaw and finally decided the reason she couldn't walk, move her arms and had slurred speech was because she was suffering from a post-viral complication.

Then her mum's instincts kicked in, suggesting it could be a tick.

Sure enough, hidden under the four-year-old's soft, blonde baby hair was an Ixodes holocyclus, also known as the Australian paralysis tick.

It had gorged itself on Evangeline's blood for four days after she and brother Ike had played near bushland at Coledale.

Evangeline was airlifted to Sydney Children's Hospital because of fears the paralysis would affect her breathing.

"Watching her deteriorate was like free-falling," said mum Kathy Doosey, a Wollongong barrister. "It was a relief to discover what was wrong and to know she would make a full recovery.

"To their credit, the medical team at Wollongong Hospital did everything they possibly could, but tick paralysis is very difficult to diagnose because it's so uncommon in people."

It is just over a week since Evangeline fell to the ground and told her mother that she could not get up.

The day before that she had been listless and struggled to walk.

"Parents should know that this could happen to their child," Ms Doosey said. "If their child is listless and experiences any weakness in their limbs, they need to know that it could be a tick."

Evangeline recovered quickly because of the early detection, but other children have taken up to six months to get well.

Paediatric neurologist and tick expert Dr Paddy Grattan-Smith said in the first half of last century the paralysis tick was considered more venomous than the redback spider, the funnel web and the blue-ringed octopus.

Between 1900 and 1945, 20 people died from respiratory failure in Australia caused by tick paralysis, most of them children.

There have been no deaths since that time because children can now be ventilated. "With modern intensive care a child should be okay," Dr Grattan-Smith said.