Sam Ballard never did anything wrong, if you ask family and friends.

The teenager from Sydney's upper north shore was having a laugh and some red wine with mates in the backyard, "trying to act like grown ups".

It was 2010 and it was a night that would change his life, and the lives of everybody around him, forever.

A slug crawled across the concrete patio and, teens being teens, a dare emerged for Sam to eat it.

One of his best friends, Jimmy Galvin, later described the moment.

"We were sitting over here having a bit of a red wine appreciation night, trying to act as grown up and a slug came crawling across here," he said.

"The conversation came up, you know. 'Should I eat it?' And off Sam went. Bang. That's how it happened."

He didn't become sick immediately, but complained of serious pain in his legs in the days after. He would be infected with rat lungwom and fall into a coma for 420 days.

The worm that infected Sam is usually found in rodents, but snails and slugs can also become infected when they eat rat faeces.

Katie Ballard with her son Sam, who became a paraplegic after eating a garden slug and died last week. Photo / News Corp

Sam contracted eosinophilic meningo-encephalitis, which many people recover from. Sam didn't.

This week, eight years after he fell ill, Sam died. The Sunday Project's Lisa Wilkinson broke the news during a sombre but brief segment.

Katie Ballard, Sam's mother, described how hard life had been for Sam. He couldn't eat for himself and needed help going to the bathroom.

While he was initially unable to move his limbs, the former Barker College student worked hard to regain some movement.

Katie had said "he understands" everything, and his mates know that was true.

Mr Galvin said he apologised to Sam for not stopping him that night in 2010. When he did, the former rugby standout "just started bawling his eyes out".

"So you know he's there," Mr Galvin said.

His close friends often visited him. They'd watch footy like they used to and share a beer, even if that meant just a sip for Sam when Katie left the room.

His eyes would always light up when they came around.

"It made his day," his mates said.

In 2011, Katie shared a post on Facebook, maintaining hope that her "rough-and-tumble Sam" would recover.

"Physios had Sam standing in the frame at the gym," she wrote. "He spent the afternoon laughing at me as I read him the sports section of the newspaper with new glasses on.

"Told him it was the stress of the last 16 months that had affected my eyesight."

Later, she wrote that "he is still the same cheeky Sam, and laughs a lot" but admitted "it's devastated, changed his life forever, changed my life forever. It's huge. The impact is huge."

Katie spent years fighting for adequate care for Sam after 2010. An initial allocation of care as part of the government's National Disability Insurance Scheme saw the family receive $471,000.

But in October, 2017, that was reviewed and slashed by more than half. Media coverage and the family's fight for additional funding and care saw the decision reversed.

Sam was 27 years old.