"We were sitting over here having a bit of a red wine appreciation night, trying to act as grownups," Ballard's friend, Jimmy Galvin, told Network Ten.
"A slug came crawling across here ... The conversation came up, y'know. 'Should I eat it?' And off Sam went. Bang. That's how it happened."
A few days after eating the slug, Ballard complained of pain in his legs. An initial fear of multiple sclerosis, which his father suffered, was ruled out, before doctors diagnosed him with rat lungworm.
Rat lungworm is a very rare cause of meningitis in Australia and can be carried by rodents, snails and slugs. While most people who are infected only ever experience mild symptoms, in rare cases the worm can cause an infection of the brain known as eosinophilic meningo-encephalitis.