Kiwi conservationist Peter Bethune getting treatment from world-leading snake bite experts after attack

A Kiwi conservationist is now getting specialised treatment from world-leading snake bite experts as he struggles to recover from a potentially deadly attack.

Pete Bethune admits he's scared as doctors monitor his delicate condition. His left leg is still severely swollen after being bitten in the Costa Rican jungle by a fer-de-lance snake - South America's deadliest.

Five days on from being rescued, his case is being followed by the country's head of infectious diseases and a snake bite expert from the WHO.

"So now what's happening with these other couple of guys getting involved, I'm more in the loop in terms of 'this is what's going to be happening over the next few days'," Bethune told Newshub.

The conservationist's liver and kidneys are doing all the hard work at the moment expelling the poisonous toxins from the bite. His latest blood tests show he's sustained long-term muscle damage.

"You know, 50 percent calf usage but I'm alive. I'll settle for that right now."

He's now developed a rash on his back and with the constant throbbing in his leg he's not sleeping.

"I felt like absolute shit. It was starting to feel like a black hole here had just sucked me in and I'm sort of worried about making bad decisions."

After years spent in the jungle cracking down on poachers and illegal mining this is the 55-year-old's first snake bite.

"I don't regret what I do. The world is a fractionally better place with me in it. There's not a lot of people that can genuinely say that."

And this setback won't stop him continuing to make his contribution.

"There are snakes in the jungle, come under gunfire multiple times. But it's what I've pursued and it's what I choose to dedicate my life to."

He's given Ted Talks on finding a cause worth dying for. You can't dispute his commitment.