GENEVA >> Under a stormy sky, on a boat to a Group of Eight summit meeting, a media-savvy Hong Kong pediatrician named Margaret Chan first met her country’s president, Hu Jintao. In a preview of the political maneuvering to come, he told her privately that China was considering backing her for the top post at the World Health Organization.

It was Beijing’s first bid to place one of its own at the head of an international agency, a signal of China’s global rise. And it worked. A few months after, in late 2006, Chan won enough votes among the organization’s 194 member states — by secret ballot, as always — to become its chief.

In what seemed like a deft political move, she publicly promised to make Africa, which controls a fourth of those votes, one of her top priorities. Hu, who was aggressively courting the continent for its resources, summed up the agency’s importance by invoking a Chinese proverb.

“We’re all in the same boat,” he told her after she took office.

Now Ebola is battering three fragile countries in Africa and with it, the WHO’s standing — in large part, Chan’s critics say, because she let governments around the world steer the agency to fit their own needs, instead of firmly taking the helm as the world’s doctor in chief.

Diplomacy is an inevitable, even necessary, part of running the world’s main health organization, vital to getting to factious countries to cooperate for the sake of global health, her critics acknowledge.

But Chan, they say, has been too willing to accommodate the wishes of governments, at times reluctant to call them to task and at other times too ready to bow to the demands of donors — even when it puts the world’s health at risk.

Not until August, after 1,000 Africans had died and Ebola had spread to Nigeria, the continent’s most populous country, did Chan declare the outbreak a global emergency.

“The WHO should have pulled out all the stops and said this is an emergency” much earlier, said Dr. Peter Piot, who discovered the Ebola virus 40 years ago.

Chan’s performance during a major health crisis has been attacked before. She was a public health administrator in Hong Kong when SARS, or severe acute respiratory syndrome, emerged from China and rapidly spread across the world in 2003. A year later, the Hong Kong legislature censured her for not pressing the Chinese government hard enough on the outbreak.

SARS was pivotal for the WHO as well, but for the opposite reason. The agency’s director-general at the time, Dr. Gro Harlem Brundtland, took an unusually aggressive stance, hectoring Beijing to share more information about the disease. When it did not, Brundtland issued a global alert anyway, overriding the concerns of affected governments.

But after taking over the WHO, Chan took a far more cautious approach on Ebola, leaving it to her African regional office to work with local government officials who were nervous about ringing the alarm.

By the time Chan declared the Ebola outbreak an emergency, hundreds more people had died than during the entire SARS epidemic. Now, the death toll for Ebola has exceeded 8,000.

Chan defended her record on Ebola, saying that she followed protocol by leaving it to the Africa office to respond in the early months of the virus. She acknowledged that getting a grip on the WHO’s regional offices, which are effectively controlled by local governments, was the most intractable political issue in the organization and that, in hindsight, she wished she had acted a little earlier to “mount a much stronger, more aggressive response.”

Sounding the alarm can come with a price, as Chan had learned. When swine flu broke out in 2009, she was criticized for overreacting and declaring it a pandemic. While an independent review later found that she was right to do so, some critics and supporters now wonder if the experience made her gun-shy in responding to Ebola. She says it did not.

“We are not forgiven if politicians perceive we might have gotten it wrong,” said a former WHO official.

Under Chan’s leadership, the WHO has also been accused of deferring to the Syrian government of President Bashar Assad when polio made a comeback in that country in late 2013. Nor did the agency say anything publicly about Saudi Arabia’s failure to detail the spread of Middle East respiratory syndrome last year.

At the end of May, as Ebola deaths neared 200, Chan barely touched on it in her speech to the annual conclave of the WHO’s 194 member states in Geneva. Instead, she addressed a host of issues dear to various governments, from cancer to sugar consumption.

“She has very assiduously promoted the idea that it is member states of WHO that are the owners and decision-makers in a fundamental way,” said Nils Daulaire, the former U.S. representative on the health organization’s board. “I’ve been at countless meetings at WHO where Dr. Chan has turned to participants and said, ‘I am elected by you to lead the organization in the way you decide.’”

Chatham House, in a report published in May, described the organization as unduly “politicized.”

“The interests of the member states bubble up and they guide WHO,” said Wafaa El-Sadr, a professor at the Mailman School of Public Health at Columbia University. “On the other hand, the world’s expectation of the WHO is that it’s leading from above. That’s a conflict.”

Chan had been warned about Ebola in late March, when the United Nations peacekeeping mission in Liberia sent increasingly dire cables about the virus, calling for help from Chan and others about what to do. Her office said it had no record of receiving them.

But she sharply disputed the suggestion that she should have declared Ebola a global health concern earlier in the year. “If it’s a matter of a few days, yes,” she said, “but definitely not months ahead.”

She said she felt no pressure to play down the severity of the outbreak early on, and pointed out that the WHO’s job was limited to helping governments respond better, not sending an army of health workers to do it for them.

Trained as a pediatrician in Canada, Chan, 67, shot to prominence as a health administrator in Hong Kong in 1997 when she tried to reassure an anxious public about avian flu, famously boasting of eating chicken every day — only to quickly retract and order the culling of poultry on the island. Still, she won plaudits for her leadership at the time.

Then in 2003, SARS came from China to Hong Kong, striking the island with a vengeance and virtually shutting it down for weeks.

The Hong Kong legislature later singled out Chan for “errors in judgment,” including not pressing China for more information. Her defenders said that no amount of pressing could have made Beijing more transparent at the time.

The report forced several Hong Kong officials to resign, including Chan’s boss. But by then, Chan had moved out, plucked for a senior job at WHO headquarters — and then in 2006, nominated to head the agency.

In March 2009, a fatal flu strain emerged in Mexico — H1N1, known then as swine flu. By mid-June, when 73 countries had reported suspected cases, Chan convened a late-night news conference and told the world that a full-blown flu pandemic had arrived.

The fatalities turned out to be limited, but an independent review of the agency warned that the WHO’s internal problems had left it unprepared for the next serious outbreak.

It cited Geneva’s inability to supervise its regional offices, its inability to put medical boots on the ground, and an ambiguous mandate that forced it to be “simultaneously the moral voice for health in the world and the servant of its member states,” as the head of the panel, Harvey V. Fineberg, put it.

These were precisely the shortcomings that Ebola would expose. But they were not addressed. Instead, because of the global financial crisis, the WHO’s budget shrank severely under Chan. Donors cherry-picked what they wanted to pay for. Disease surveillance was radically pared back.

Only the most “anemic” structural reforms were considered, said David Fidler, an Indiana University law professor who specializes in global health. Chan, he said, “has no enthusiasm for challenging member states with respect to controversial issues.”

Crucially, the power of the WHO regional offices was preserved. Each regional head was elected by countries in the region; they in turn had the power to dole out jobs and money to those countries. They were answerable to the head office in Geneva only in theory.

“I was told when I wanted to push that: ‘Don’t even go down that path,’” Chan said.

Then came Ebola.

The first of the Ebola cables from U.N. peacekeepers in Liberia was sent to headquarters on March 24, with a copy to Chan in Geneva: more than two dozen people dead in Liberia and neighboring Guinea.

A week later came a second cable, then a third, also from the peacekeeping mission in Liberia, each one more alarming. The virus was detected in the crowded capital, Monrovia. In a town near the border, visibly sick patients were not isolated, but living among the healthy, posing intense risks of transmission. The U.N. mission chief, Karin Landgren, appealed for “definitive advice.”

All the while, a local WHO representative reassured his U.N. colleagues that the virus would soon subside, just as it had elsewhere in previous outbreaks.

On July 29, a cable from the Liberia peacekeeping mission chief to U.N. headquarters — also copied to the WHO in Geneva — called the Ebola situation “unprecedented and rapidly deteriorating.”

By then, hundreds of health workers in the region had died. An infected Liberian man traveled to Nigeria by air, taking the virus with him. That was the trigger, Chan said, to assess the global risks.

“I said that, ‘Well, whether countries like it or not, I’m going to call an emergency committee to let the experts tell me whether or not the risk of international spread is there,’” she said.

By August, one senior United Nations official bluntly told the secretary-general’s special envoy for Ebola that the WHO “has consistently been behind the curve.”

That same month, the secretary-general, Ban Ki-moon, told Chan that he planned to appoint a new mission to coordinate the Ebola response, a clear signal that her agency’s response had been insufficient.

“The world needs a WHO,” Piot said. “But it has to become a better one. My concern is once this epidemic is over, things go back to business as usual.”