The clue was supposed to be in the title: “It’s Merge Time.”

By now, Survivor’s audience — stable in number after 31 seasons, if no longer topping the charts — is used to the routine.

Twenty or so contestants are thrown together in a remote tropical location and are split into tribes.

At some point, after three weeks of fending off the elements, surviving daily challenges and scraping through weekly eliminations, whoever’s left in the two tribes merges into a single group of conflicting personalities. And then it’s every man and woman for himself/herself until the final vote to decide a winner.

The merge in Survivor: Kaöh Röng happened last week; this week’s episode will pick up with the new, post-merge group figuring out a way to outwit, outlast and outplay the opposition until just a handful remain. And then there was one…

The merge is traditionally a highlight episode of the season. The number of survivors is now manageable enough that the audience watching at home can finally figure out whom to root for — as with presidential campaigns, a battle of the least objectionable — and the remaining survivors realize they will now have a direct say in the final outcome, once they make the jury.

It’s a time-tested TV formula that has outlasted many long-running dramas, sitcoms and other reality series, and in just a couple of weeks’ time Survivor will have outlasted American Idol — something that would’ve seemed unthinkable just a few short years ago.

Longtime Survivor viewers have learned what to expect. What unpredictability there is revolves around human behavior for the most part, and the behavioral imperative that no one can keep a secret, or will do what they say they will do.

This time was different, though. For the second time in just seven episodes — 21 days in filming time — a contestant was evacuated from the game for medical reasons (below, right, assessing the condition of Caleb Reynolds before evacuation). This followed a hasty assembly of the remaining contestants on the remote Cambodia beach where Kaöh Röng was filmed and a medical check of no fewer than four of the remaining contestants. This followed a similar medical evacuation just days earlier, when a half-dozen Survivor contestants were checked for heat exhaustion after a particularly grueling group challenge under the beating tropical sun.

In all, 14 Survivor contestants have undergone medical evacuation since the program’s conception in the spring and summer of the year 2000 — not many in a world where so many people struggle with real-world survival, but many more than on similar competition shows like Hell’s Kitchen or American Idol, where the only real danger in the show’s early years was the need for a tetanus shot after being mauled by Simon Cowell. Occasionally a chiropractor may be called in after an aging celebrity throws his back out on Dancing with the Stars or a psychologist may be parachuted in to treat a contestant for shattered nerves on Hell’s Kitchen, but Survivor has always been in a league of its own.

A direct descendant of Eco-Challenge, producer Mark Burnett’s expedition race series that pitted professional outdoor types — Navy SEALS, firefighters and combat veterans — against each other in a test of their survival skills over rugged terrain, Survivor also inherited Eco-Challenge’s behind-the-scenes medical team. Burnett, a former British army commando and squad leader in the Falklands War, was determined from the outset that if anything went wrong on Survivor, as it surely would when you place city slickers in an environment as unforgiving as the wilds of Cambodia, or the jungles of Gabon in West Africa for that matter, he wanted a combat-hardened medical team there and not pretend TV doctors.

Interestingly, for all the scary threats facing anyone sleeping outdoors in a tropical environment for the first time — everything from snakes and spiders to insects of every size and description — it’s the genuine no-see-ums, like ticks, sandflies and microscopic bugs, and climate extremes between hot and cold that pose the most problems.

Survivor has never had a problem with a venomous snake — though it’s certainly possible, given the remoteness of some locations — but an invisible bug or germ with the ability to affect an entire group of people is cause for alarm, and alarm is exactly what host Jeff Probst showed when he appeared unexpectedly at the survivors’ camp in last week’s episode, medical team in tow. This time, the problem wasn’t mass-induced hysteria or collective heat exhaustion but rather a rash of extremely nasty-looking bug bites, some of them on the verge of major infection.

The typical Survivor viewer looking on from the safety of the family couch quickly got an unwanted medical education. There would be no tribal council this week, no vote or elimination.

The social media sites briefly flared with agitation and annoyance, anger even — how can they do a merge without a tribal council or elimination? We’ve been cheated!

And some of the Survivor contestants struggled to find the proper perspective — my only ally in the game is gone; my alliance is broken. What am I going to do now? Woe is me!

For anyone watching at home, though, especially anyone with a memory of Eco-Challenge and some of the genuinely life-threatening accidents in expedition racing in general, it was a sobering moment and a reminder that, for all its goofy absurdity and popular-culture tropes —“Fire is life”; “the tribe has spoken”; “do you want to know what you’re playing for,” etc. — Survivor is a real show that puts real people through real hardships.

David Letterman used to lampoon Survivor for not being all that — “Oh here comes Jeff Probst with a cheeseburger and fries" — but Probst himself has said that the insect bites, the heat, the damp, the lack of food or even potable drinking water at times, coupled with the stress of being forced to coexist with people you really, really don’t like, has a way of breaking down the immunity system and bringing out the worst — and best — in people.

Thousands of contestants apply each season to be on Survivor, and there are any number of waivers, disclaimers and other legal documents that have to be signed. Once there, most contestants are loath to leave, even if the medical team tells them they have to go.

Neal Gottlieb, a 38-year-old Peace Corps veteran and ice cream business owner from Sausalito, CA, was no different. He had numerous welts and semi-infected bug bites, most of which looked bad, but not life-threatening. One, however, was dangerously close to a joint.

In his CBS Survivor bio, asked what he would take to the island if he could, he replied: “I would take a big comfortable bed with high thread count sheets, a down comforter and lush pillows to facilitate good nights’ sleep, and an assortment of fake immunity idols and fake printed clues on convincing paper to fool (the other) contestants into thinking that they have immunity.”

He might have added a really good big spray, but he was not to know.

As it was, the exchange between Gottlieb, Probst and medical-team director Dr. Rupert Hurry (twitter: @drducatisti) was telling. (All three pictured at top.)

“Everybody here knows it’s a real deal and hopefully we can contain it,” Probst said, without even a trace of his familiar jocularity.

“I’m looking to see what it’s potentially become,” Dr. Rupert said, examining a lesion on Gottlieb’s back. “That one’s in the skin but there’s nothing under there that would immediately do damage. It’s a big, nasty spot, but I don’t think it’s life-threatening.”

Another lesion, closer to Gottlieb’s knee, was a different matter, however.

“If the infection goes into a joint, an infection in a joint can destroy it in a matter of hours,” Dr. Rupert said. “Extremely dangerous.”

Gottlieb insisted he was fine: All he needed was a couple of days to walk it off.

“The problem is,” the doctor continued, “if that gets worse and it goes into your joint, this is for life. These can affect you years down the line. I want you to run around and do this when you’re (in old age). I don’t want to leave this. I think this has the potential to get worse.”

“I don’t want to leave, Jeff,” Gottlieb insisted.

“I can see you’re getting emotional, sensing,” Probst said, turning to the doctor.

“Doctor Rupert, let’s be really clear. You’re pulling Neal from the game?”

“I think I have to.”

Gottlieb was inconsolable.

“It took a huge amount of (effort) to come out here, from watching the show beginning in the summer of 2000. I was working in a cubicle, in a job that was thoroughly uninteresting; I didn’t love my life. So I’ve had quite the journey, just as you have, over the last 13 years. And all of a sudden I got to come on Survivor, thinking I could really compete.” His voice trailed off. “I’ve had a great 19 days.”

“We’re going to take you from here, get you to hospital and get this fixed,” Probst said. “You come back, you’ll be a jury member. You won’t have a chance to win but you’ll have a vote to decide who does win.”

Over the years, Burnett and Probst, now one of the series’ producers, have given the medical team the final say, no ifs ands or buts. The doctor’s word is final. Expedition racers have nearly died on Eco-Challenge and Survivor’s producers are determined not to have a repeat on their own, in a family show that airs at 8 p.m. ET, family-viewing hour, on CBS.

Prior to this season, Survivor featured medical evacuations on seven occasions: in Survivor: The Australian Outback (2001), Survivor: Panama (2005), Survivor: Micronesia (2007), Survivor: Tocantins (2008), Survivor: Samoa (2009), Survivor: One World (2011) and Survivor: Caramoan (spring 2012).

Survivor: Philippines (fall 2012) featured a twist in which three medically evacuated contestants from earlier seasons, Michael Skupin (Australia, right), Jonathan Penner (Micronesia) and Russell Swan (Samoa) returned to play against new castaways.

Signed liability waivers are now standard practice in the adventure-racing business, but legal experts say organizers can still be held liable if they’re judged to have done something reckless.

Waivers are more comprehensive than they’ve ever been, and will cover almost anything.

Even so, Paul Figley, a professor of tort law and legal precedent at American University’s Washington College of Law told the Baltimore Sun in 2013, no waiver can take away a participant’s right to sue.

Several years ago, while Survivor was filming in virtual secrecy in Gabon, one of the most remote, isolated jungle countries on Africa’s Atlantic coast, I asked CBS consigliere Gil Schwartz if he had any information he cared to share about what was going on there.

I had traveled extensively throughout East and southern Africa, and was curious how Survivor contestants might cope in an environment I knew to be potentially hostile. Gabon is like The Congo, but with better coastal scenery. It’s Joseph Conrad country, real Heart of Darkness stuff, but without the guns.

“I haven’t had any phone calls,” Schwartz replied, without missing a beat.

“Trust me, that’s a good thing.”