MANILA, Philippines — The fictional news stories pop up on Facebook faster than Paterno Esmaquel II and his co-workers can stamp them out.

Rodrigo Duterte, the president of the Philippines, debated a Catholic bishop over using violence to stop illegal drugs — and won. Pope Francis called Duterte “a blessing.” Prince Harry and his new wife, Meghan Markle, praised him, too.

False news like those examples is so established and severe in the Philippines that one Facebook executive calls it “patient zero” in the global misinformation epidemic. To fight back in this country, the Silicon Valley social media giant has turned to Esmaquel and others who work for Rappler, an online news startup with experience tackling fake stories on Facebook.

While Rappler’s fact checkers work closely with Facebook to investigate and report their findings, they believe the company could do much more.

“It’s frustrating,” said Marguerite de Leon, 32, a Rappler employee who receives dozens of tips each day about false stories from readers. “We’re cleaning up Facebook’s mess.”

On the front lines in the war over misinformation, Rappler is overmatched and outgunned — and that could be a worrying indicator of Facebook’s effort to curb the global problem by tapping fact-checking organizations around the world. Civil society groups have complained that Facebook’s support is weak. Others have said the company doesn’t offer enough transparency to tell what works and what doesn’t.

‘Have a lot more to do’

Facebook says it has made strides but acknowledges shortcomings. It doesn’t have fact checkers in many places, and is only beginning to roll out tools that would scrutinize visual memes, like text displayed over an image or a short video, sometimes the fastest ways that harmful misinformation can spread.

“This effort will never be finished, and we have a lot more to do,” said Jason Rudin, a Facebook product manager.

For fact checkers themselves, the work takes a toll. Members of Rappler’s staff have received death and rape threats. Rappler brought in a psychologist. It debated bulletproofing the windows and installed a second security guard.

The job also requires patience. One busy day this summer, the newsroom’s fact-checking team asked Esmaquel, who covers religion, to look into the story about Duterte’s debating the bishop. Even though the story had been shared nearly 4,000 times and had reached more than 1 million followers, he knew right away that it was a hoax. But he still had to call up the Archdiocese of Manila for comment.

“I said, ‘Father, I know that this is fake, but I need a quote from you,’” he said.

This kind of work doesn’t end for Esmaquel, 32, and his colleagues.

“We kill one,” he said, “and another one crops up.”

Threats and deceit

Rappler has experience battling misinformation. It was founded as a scrappy investigative reporting and entertainment outlet in 2012 by Maria Ressa, a former CNN bureau chief in Manila and Jakarta, Indonesia. She persuaded three female friends — a group she nicknamed “the manangs,” a Tagalog word for old ladies or sisters — to leave their high-powered jobs at news stations and magazines. They shared an optimism that the internet would be a platform for the powerless to find a voice and that Rappler, which is a hybrid of “rap” and “ripple,” would be a vehicle for social change.

Instead, the internet in the Philippines became an outlet for threats and deceit.

That is particularly true on Facebook, through which about 97 percent of people in the Philippines get access to the internet. Before the Philippine election in May 2016, fake accounts appeared on Facebook spreading positive stories about Duterte, who was running for president as a blunt-spoken, anti-drug populist. They also excoriated Duterte’s opponents, often with personal and inflammatory attacks. Much of the content was untrue.

After he won the election, Duterte waged an anti-drug campaign that has led to thousands of deaths, provoking an international outcry. Many of his critics and political opponents, including Rappler, have run into legal problems. Facebook campaigns have underpinned much of this activity. At times, officials in Duterte’s administration have openly shared misinformation on the platform.

The administration did not respond to a request for comment. It has denied past accusations by Rappler that it is behind misinformation campaigns.

The developments alarmed Ressa. Armed with details of dozens of fake accounts, she met with three regional Facebook executives in August 2016 in Singapore to express her warnings and ask the company to take down the fake accounts.

“I said, ‘If you don’t fix this, you’ve got U.S. elections coming up in November,’” Ressa, 55, recalled.

In the days after the U.S. election, Facebook reached back out to Ressa, asking for her data. In December, it agreed to remove the 26 fake accounts that Rappler had identified, the company said.

For Ressa, the response was not enough.

Death threats

Duterte set the tenor. Once elected, he hired Facebook personalities who had helped him sweep to power. They began to distribute fake stories and images taken out of context and introduced new words like “presstitute” — a mash-up of press and prostitute.

“It was like the guns were trained on the press,” said Gemma Bagayaua-Mendoza, who runs Rappler’s fact-checking team. Rappler’s star political reporter, Pia Ranada, 28, found herself at the center of the storm. In news conferences, Duterte would make thinly veiled threats, singling Ranada out, she said. Explicit death threats aimed at her on Facebook would follow.

Natashya Gutierrez, 31, another reporter, has turned off the comments on her Facebook page. “There was one comment that I will always remember,” she said. “It was something like: ‘You should take a gun and shoot yourself in the mouth.’”

In April, Facebook created an official news verification program and made Rappler one of its third-party fact checkers as part of a commercial partnership, a move that reporters there welcomed. Neither Facebook nor Rappler would disclose financial terms.

“We recognize the role Facebook plays in the Philippines, and are taking responsibility for that,” said Clair Deevy, director of Asia Pacific community affairs at Facebook.

A team of four researchers at Rappler was quickly set up to look for bad content and then send it on to reporters to discredit and notify Facebook. The results, however, are mixed.

“We see repeated claims that we have tagged and they are still there,” Bagayaua-Mendoza said.

Just one example: That story about Duterte and the bishop is still circulating online. When its fact checkers determine that a story is false, Facebook pushes it down on users’ News Feeds in favor of other material. Facebook does not delete the content, because it does not want to be seen as censoring free speech, and says demoting false content sharply reduces abuse. Still, falsehoods can resurface or become popular again.

What about memes?

In addition, misinformation here often travels in the form of memes, which have not officially been included in Facebook’s third-party verification program. This month, Rappler began testing a program that Facebook has worked on to flag fake videos and pictures. (It is too early to tell if it is working, Bagayaua-Mendoza said.)

The relationship between Rappler and Facebook isn’t always smooth. Ressa still points out flaws in Facebook’s system and questions its priorities. She recalled telling Mark Zuckerberg, the company’s chief executive, at a lunch last year that the problem had to be fixed because 97 percent of people in the Philippines used Facebook. His response, she said: What about the 3 percent who didn’t?

Facebook declined to comment on the lunch.

There is no question in Ressa’s mind about who is responsible for false news in the Philippines. “Facebook broke democracy,” she said. “Now they have to fix it.”