Dr. Adrian Cohen, who's worked behind-the-scenes on every "Survivor" as the show's primary on-site doctor, says "Survivor Guatemala: The Maya Empire," (search) which premiered last Thursday, is the most medically challenging one yet.
"It's probably the toughest one to date, and that's a big call," says Cohen, who prefers to be called "Ado."
Evidence of just how tough "Survivor Guatemala" will be was found in the vomiting, injuries and dehydration that followed the tribes' 11-mile trek through the jungle in last Thursday's opener — capped off when Jim Lynch, the 62-year-old eventually booted, revealed he'd snapped his bicep.
"Physically, this has been the toughest one for the people there. It's a real killer," Cohen says. "At Times, it got to be 122 degrees in the jungle.
"Even though the show is based around water, it's the first time since we were in Africa that they can't drink the water directly, bathe or wash because of crocodiles."
Cohen, a trauma physician who flew on thousands of helicopter-rescue missions in his native Australia, runs Immediate Assistants (search), which provides on-site medical services to corporate events, TV shows and movies.
He and his staff of doctors and nurses have been on location with each "Survivor" since the show's 2000 premiere. Cohen hooked up with series creator Mark Burnett (search) after working on Burnett's first reality series, "Eco-Challenge."
"This one is brutal and isn't going to get any better," says Cohen of "Survivor Guatemala," set in the jungles of the Central American country. "The Australian Outback was a picnic compared to this.
"We're always concerned about hepatitis, and bugs are always a problem," he says. "They cause itching and sores that get scratched and get infected.
"And, in Guatemala, there are bugs that carry dengue fever and malaria, which is a big problem there."
And then there are the falling coconuts — which instill a sense of fear in Cohen.
"More people die of coconut injuries every year than parachute injuries," he says. "You don't see local people sitting under coconut trees for a reason."
Cohen says he goes to each "Survivor" location six months before the cast and crew arrive. The show's "medical clinic" is usually a few rooms in an old hotel — or a clinic is built on-site from scratch.
"We end up with a couple-hundred square feet with an ER area, advanced resuscitation equipment, anesthetics, initial first aid and advanced life support," he says.
"We don't kid ourselves that we're Cedars-Sinai — I've got a staff of two doctors, two nurses and three paramedics, and it's our job to be challenged at each camp.
"Our job is to keep people on the show . . . and make sure everyone goes home in one piece — both the cast and the crew."