(CNN) – It was just a silly challenge among teenagers. What could happen to him when swallowing a small slug?
So the Australian teenager Sam Ballard grabbed the slimy creature and ate it. He had no idea that the slug had a life-threatening worm that would put him in a coma for more than a year, paralyze his body and eventually kill him.
'Trying to act like adults'
In 2010, Sam, an avid 19-year-old rugby player, was drinking with Jimmy Galvin and several more of his friends when a slug began crawling around the yard of Galvin's house in Sydney.
"We were sitting here, with a little wine, trying to act like adults," Galvin recalled in an interview at video this year with Lisa Wilkinson from "The Sunday Project", a talk show on current affairs that airs on Channel 10 in Australia. CNN looked for Galvin, but has not received a response.
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"And then the conversation came up: 'Should I eat it?' "recalled Galvin. "And then Sam went and bang, that's how it happened."
After passing the slug, Sam weakened and complained of severe pain in his legs, according to "The Sunday Project." Sam's mother, Katie Ballard, told the news that at first they were worried she might have multiple sclerosis, which had affected her husband. But the doctors discarded it.
Then Sam told his mother that he had eaten a slug.
Sam Ballard swallowed a slug without thinking that it would cause his death.
"And I said, 'No, nobody gets sick of that,'" said Katie Ballard, whom CNN also sought to contact.
Soon, however, doctors told them otherwise. Sam had developed rat lungworm disease from the infected slug, changing his life forever.
What is rat lungworm disease?
Rat lungworm disease is caused by a parasitic worm called Angiostronjilus cantonensis. As the name implies, the parasite lodges in the lungs of the rats and is then excreted in the secretions.
A slug, a snail, a freshwater crab, shrimp, prawns or frogs, eat rat manure or the parasite makes its way to the creature that infects it. The fish, however, do not spread the parasite.
Humans can become infected if they eat raw or undercooked contaminated animals, or vegetables that carry snails or slugs that have not washed well.
In addition, according to the US Centers for Disease Control and Prevention, beverages can be contaminated with worms if they are left open for snails and slugs to enter.
Instead of traversing the digestive tract, the larvae of the worm "can get lost and go to the brain and stay there," said Heather Stockdale Walden, an assistant professor in the Department of Infectious Diseases and Pathology at the University of Florida. The parasite is not transmitted from human to human.
"When it reaches the brain, you can have eosinophilic meningitis," said Walden, which is an inflammation of the membranes that surround the brain and spinal cord.
Symptoms may include headaches, nausea, vomiting, fever and stiff neck, the CDC detailed.
'So full of love'
Most cases of rat lungworm disease are typically mild. But in some cases, like Sam's, the disease can cause catastrophic damage.
Shortly after the diagnosis, Sam fell into a coma, where he remained for 420 days, Ballard said in the Australian news report. He awoke paralyzed, unable to eat without a tube or move without an intense effort. It required attention 24 hours a day, seven days a week.
But the disease did not affect his mental faculties, his family and friends said.
"It's there, 100%," Galvin told "The Sunday Project." "I apologized to Sam for everything that happened that night in the backyard, and he just started crying, I know he's there."
Last week, Sam died, wrote Wilkinson, of "The Sunday Project," in a blog.
"Sam died on Friday morning at Hornsby hospital, not far from where he grew up, surrounded by 20 of the ones he loved the most in the world," he wrote.
"Katie tells me that 'the room was so full of love,'" Wilkinson said.
A funeral service will be held for Sam on Thursday, according to a post on Galvin's Facebook page.
CNN's Susan Scutti contributed to this report.