Dan Diamond is a Politico reporter and the author of "POLITICO Pulse."

Hillary Clinton has Parkinson’s, according to one Trump supporter. Or an undisclosed “cognitive illness.” Or has just endured one too many falls and too much blood thinner.

There are no numbers on just how many Americans believe Clinton is hiding a dire medical condition, but the short video of Clinton nearly collapsing and being ushered into a van on Sunday morning triggered far more than the typical concern you might expect about the well-being of a 68-year-old in a highly stressful environment. The Drudge Report's headline for nearly a day: "Will she survive?"


In a normal cycle, a politician copping to being sick and taking a break – like then-72-year-old Joe Biden's decision to cancel a foreign trip because of a bad cold, or Barack Obama's visible exhaustion on the stump — would be an excusable human lapse. Not this year. What we’ve seen is more like a coming-out party for the “healther” conspiracy on the mainstream American stage.

For months, the alt-right has pushed the narrative that something is secretly, direly wrong with Clinton. And as with many other unprovable theories that help his campaign, Donald Trump has dog-whistled to believers without ever endorsing their more extreme positions. Clinton "lacks the mental and physical stamina to take on ISIS," Trump said in Ohio last month. Her "short-circuit in the brain" when talking about the FBI's email investigation reveals "she's got problems," he added in a series of attacks.

So when Clinton got caught stumbling on camera Sunday, unable to stand through a 9/11 memorial in New York City, the healthers were ready to blow it sky-high. Multiple slow-motion and zoomed-in videos of Clinton's feet circulated thousands of times on social media. One ex-Secret Service agent said the protective detail's specific movements to help Clinton stand revealed "a different story" than her official diagnosis. And the media was more than happy to feed the mystery. CNN's Wolf Blitzer spent minutes breaking down a few seconds of Clinton dragging her feet like it was the new Zapruder film.

Asking about a candidate's health is important, as Jack Shafer astutely observed last month and more than 85 percent of voters told a Rasmussen poll. Seeking the world's most powerful job should require radical transparency, and most voters clearly want this information. And there’s no question the current process of voluntary disclosure is inadequate. Right now, candidates can cherry-pick their doctors and release piecemeal medical information. Despite their assertions, we don’t actually know how healthy Clinton or Trump are. (That's why an independent panel of doctors would be so useful.)

Remember, predicting that someone's going to get ill is a sure bet: Everyone gets sick. The average adult contracts 2 to 4 colds per year. Older Americans like Clinton — and Trump, too — are especially likely to look tired, particularly given the grueling schedule of a presidential candidate. That's why you could practically see the Clinton campaign this weekend calculating in real time: Would revealing Hillary's pneumonia only feed the rumors? As it turned out, hiding Clinton's diagnosis and issuing multiple statements monumentally backfired: It not only fueled new health conspiracies, but reinforced her existing problems with transparency.

For Trump, it was a sudden and unexpected boon – and a reminder of his candidacy’s roots in the "birther" conspiracy theory that dogged Obama's early years in the White House. Trump was one of the loudest voices pumping up doubts about Obama on his Twitter feed – and today, despite all evidence to the contrary and even the Trump campaign's weak denials, 59% of Trump supporters still believe Obama wasn’t born in the United States.

The healther conspiracies have "an important similarity" to the birther movement, says Dartmouth professor Brendan Nyhan, who's studied how conspiracies spread. "People [keep] shifting the allegations they made as previous claims are called into question," he added. "At one point, Clinton’s concussion had been faked. Later, they accused her of covering up how serious the concussion was."

And in a way, health is far more fertile ground for conspiracy-mongers. In the current climate, a single cough is powerful enough to drive a news cycle. While Obama's official long-form birth certificate briefly put at least some doubts to rest, there's no such thing as an official long-form medical record, Margot Sanger-Katz points out in the New York Times, even if Trump is pledging to release his "full medical records."

If Clinton is truly terminally ill, she's doing a horrible job of showing it. She appeared at nearly 40 fundraisers in August; she's constantly in front of cameras and crowds. Vox's Ezra Klein describes spending a "brutally hot" day on the campaign with Clinton as she gave a high-energy speech to thousands in North Carolina, did multiple press interviews and then glad-handed with staffers. "I was exhausted just watching her," writes Klein, aged 31 at the time.

Until a few decades ago, a candidate could hide a secret illness from voters, or the press would tacitly agree to ignore it. Franklin Roosevelt couldn't walk without assistance. At the time he was pulling America away from the nuclear brink during the Cuban missile crisis, John F. Kennedy was in the throes of painkillers and taking as many as eight medications per day.

Today, there are no safe spaces — not in the real-time, round-the-clock circus that's 2016, when every crowd contains dozens of camera-phones and citizen journalists waiting to capture a single misstep. In 13 months of non-stop campaigning, a secretly sick Clinton should've made more visible stumbles before Sunday.

It’s not clear how much a president’s health should matter to voters. Abraham Lincoln likely suffered from clinical depression – a diagnosis that many voters would now think of as disqualifying. While in the Oval Office, George H.W. Bush was diagnosed with a thyroid condition called Graves' disease. Voters didn't treat it as an issue then, and he's still alive today, 25 years later.

But regardless of whether a candidate's health actually matters, voters have clearly decided that Clinton's does. That's one reason her campaign on Monday vowed to release even more medical information in the coming days. Which is a small irony, because if anyone could stand to be more transparent about his health, it's her opponent. We don't know much about Trump's health, beyond a short letter that his doctor admitted to writing in five minutes. The signature line? A bizarre rhetorical flourish — "Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency" — that doesn't square with the 70-year-old's penchant for fast food and medical deferment from Vietnam. So far, the same alt-right voters who have been so eager to advance wild theories about Clinton's health have given Trump a pass.

And the Republican nominee isn't just being held to a different standard; he's embracing it. Trump's strategy to prove he’s healthy now involves more than a note from a doctor who later backed away from it. He’s advertising his health by appearing on the Dr. Oz show this week — a TV doctor whose credibility is so bad, his own boss admitted that Oz is "full of shit,” and whose academic colleagues have petitioned his university to dissociate itself from him. In some ways, it's a match made in misinformation heaven.