Jack Osbourne's scariest moment in life was when he contracted leptospirosis.

The 'Adrenalin Junkie' host is normally fearless from all the stunts he has done for the show, but admits he was terrified when he caught a mystery illness in the jungle.

He said: "When we were doing 'Adrenalin Junkie' I got really sick. I was in the hospital with about ten doctors in the room and no one knew what I had. They'd just come in and say, 'Your liver's not really working, neither are your kidneys.' They basically told me that I was dying without saying it - that was pretty scary. "

Although he thought he was going to die, Jack said he had no time to think about the consequences as he was so sick, he was just trying to keep his body going.

He added to Britain's OK! magazine: "I know people say that your life flashes before your eyes, but I was too busy ejecting fluids from both ends to really think about the life I could possibly be missing.

"It took about five days for a doctor to realise what was wrong - I had leptospirosis. I got it in the jungle, I had leach bites on my feet and I had stepped in rat p**s."

In 2007, Jack had another brush with death when he almost froze to death filming 'Adrenalin Junkie' in Finland. He thankfully survived both incidents and is now engaged to girlfriend Lisa Stelly, who is expecting the couple's first child in April 2012.