When people started dying of Ebola in Liberia, Clarine Vaughn faced a wrenching choice: Should she send home, for their own health and safety, four American doctors working for Heartt, the aid group she led there? Or should she keep them in the country without proper supplies or training to fight the virulent, contagious disease, which was already spreading panic?

After much agonizing, Ms. Vaughn, who lives in Liberia, pulled the doctors out and canceled plans to bring in more. The African physicians and nurses left behind told her they understood, but felt abandoned. They said, “We need you guys here,” she recalled.

Since then, Ms. Vaughn has wondered if the American doctors might have made a difference, and she asked the aid group AmeriCares to help. It sent in a planeload of supplies that landed in Monrovia, the Liberian capital, last Sunday.

3 Liberian Health Workers With Ebola Receive Scarce Drug After Appeals to U.S.AUG. 16, 2014 

The departure of many Western development workers from Guinea, Liberia and Sierra Leone, the West African countries hit hardest by Ebola, has further weakened the region’s understaffed health systems at the very moment they are facing one of the most volatile public health crises ever. Liberia, population four million, has fewer than 250 doctors left in the entire country, according to the Liberia Medical and Dental Council. Seven doctors there have contracted Ebola, and two of them have died.

“The locals’ seeing this mass exodus of expatriates has contributed to the sense that there’s an apocalypse happening and they’re in it on their own,” said Raphael Frankfurter, executive director of the Wellbody Alliance, which provides clinical services in a diamond-mining district of Sierra Leone bordering Guinea, where the outbreak began.

Mr. Frankfurter, too, sent his four American volunteers home for fear they might fall ill. They left behind 160 Liberian staff members. “It’s certainly not in line with our values, because it’s just such a glaring inequality,” he said. But “it’s a very scary place to get sick right now.”

As an array of international organizations, wealthy countries and charitable groups gear up to provide desperately needed resources to fight the outbreak, the absent doctors and volunteers are a reminder of the daunting practical obstacles. Many African health workers battling Ebola are contracting it themselves. At least 170 workers have gotten the disease, according to the World Health Organization, and more than 80 have died.

Those sickened include Dr. Kent Brantly, an American now recovering in an Atlanta hospital after receiving ZMapp, an experimental drug. Three Liberian patients received ZMapp on Friday, according to Tolbert G. Nyenswah, a Liberian assistant minister of health and social welfare. The patients signed consent forms stating that they understood the risks of the untested drug, and waived liability for any adverse effects.

The doses had been flown into Liberia after appeals from President Ellen Johnson Sirleaf of Liberia to President Obama and senior American officials. Its arrival last week lifted morale and “raised the hope of everybody,” Mrs. Johnson Sirleaf said. The situation, however, was volatile. On Saturday afternoon, several hundred people in an area of Monrovia known as the West Point slum broke through the gates of a former school that had been converted days earlier into a holding center for people with suspected Ebola.

Samuel Tarplah, 48, a nurse running the center, said Saturday evening that the protesters wanted to shut it down. “They told us that we don’t want an Ebola holding center in our community.” He said the intruders stole mattresses, personal protective equipment, even buckets of chlorine that had just been delivered. “They took everything.”

Fear is complicating the huge increase in aid that is needed: food for people in areas that have been cordoned off; laboratory supplies to test for the disease; gloves, face masks and gowns to protect health workers; body bags for the dead; bedsheets to replace those that must be burned. Airlines have canceled flights that could have carried in such supplies, despite assurances from the W.H.O. that properly screened passengers pose little risk. Positions on aid teams remain unfilled.

Hundreds of workers for Doctors Without Borders have fought the outbreak since March. The group’s president, Dr. Joanne Liu, said there was an acute need for materials as well as for more human resources — and not just experts and bureaucrats, but also the kind of person who is ready to “roll up his sleeves.”

“What we have to keep in mind is we are facing today the most devastating and biggest Ebola epidemic of the modern times,” Dr. Liu said. “There is fear, there is a front line, the epidemic is advancing, and there is a collapse of infrastructure.”

A more muscular effort to fight the outbreak began lumbering to life over the past week.

The newly appointed United Nations coordinator for Ebola, Dr. David Nabarro, wrote in an email that he had his “head right down working through some extremely challenging stuff under tight time pressure.”

“All of us are going to have to perform in an outstanding way over some months,” Dr. Nabarro added in a phone interview. “For many, the image is fearful to a degree that it makes it very hard indeed for them to do anything other than think about their safety and the safety of those they love.”

The W.H.O.’s sole in-house Ebola specialist said he was following his doctor’s advice to take the week off work. His colleagues drew up plans to coordinate the international effort and recruited employees from other agencies to help with data management and field work.

With commercial flights dwindling, the United Nations’ World Food Program began an air service for humanitarian workers on Saturday. “The virus is spreading, and we’re all suddenly realizing we need to do more,” said Denise Brown, the agency’s emergency coordinator for the crisis.

The agency studied whether food stockpiled in the region for refugees fleeing a military crisis in Central African Republic could be moved to help people in what Ms. Brown called “hot zones.” But planning was complicated by the refusal of some countries to receive ships that had stopped at ports in Guinea, Liberia and Sierra Leone, she said. And the movement of food from domestic stocks into quarantined areas stalled as the World Food Program and W.H.O. sought ways to keep transporters safe and to ensure that deliveries did not cause people to congregate, risking further transmission of the disease.

Dr. Marie-Paule Kieny, a W.H.O. assistant director general, said that while it was “important to limit the movement in and out of the hot spots,” there was an urgent need to provide food and drinking water in communities cordoned off by the military to “make sure we don’t add a humanitarian disaster on a difficult health problem.”

Dr. Kieny has begun cataloging available doses of experimental drugs and vaccines in preparation for a Sept. 4 meeting on their possible use and testing.

A Unicef staff at a supply depot in Copenhagen is working to mobilize medical treatments, burial supplies, and millions of bars of soap and disinfectants for use in homes and health centers, many of which lack basic sanitary supplies. “This is just the beginning of the intensification,” said Shanelle Hall, director of the supply division.

The director of the Centers for Disease Control and Prevention, Dr. Thomas R. Frieden, said the C.D.C. had sent 50 experts to help local governments keep track of where people are getting sick and set up emergency operations centers — a challenge, judging from a Liberian Health Ministry report that in the hardest-hit area of the country, the County Surveillance Office has no computer for data management.

The American military says it has trained over 230 Liberian soldiers to use protective equipment and support health efforts.

The World Bank is allowing Liberia to use $6 million in current loans, which were intended to strengthen health systems, instead to buy ambulances, pickup trucks and protective suits for national laboratory workers, and to provide hazardous duty pay to health workers in hopes of attracting back some of those who fled their jobs in fear.

“Skilled health care workers with the right equipment can snuff this out,” said Dr. Jim Yong Kim, president of the World Bank, which advised the government to transfer $4 million from its central bank to the United Nations to make those purchases flow more quickly.

Mrs. Johnson Sirleaf, the Liberian president, said that she had not spoken with Dr. Kim about a $200 million plan, recently announced for the three most affected countries, but that she welcomed the new grants and loans, many of which will require approval from the World Bank’s board.

Liberia’s central bank established a separate trust fund for the Ebola containment effort, with an initial $5 million. Mrs. Johnson Sirleaf said she hoped that her government, which has invested in improving financial management, would be informed of any money granted directly to aid groups “so we can keep a comprehensive picture of what amounts have been mobilized in the name of Liberia.”

The single treatment center for Ebola patients in the capital area, ELWA Hospital, was at overflow capacity. In recent days, one health official estimated, it had 70 patients, more than twice as many as the units were designed to hold. A new, 120-bed unit was being prepared.

In the interim, the holding center at West Point, where the protests occurred on Saturday, was established. A photographer for Getty Images, John Moore, said the crowd removed patients from the ward, including a child. “One of the protesters picked up the young girl and carried her dangling from one arm,” he said.

“The main message was that this was a hoax, and these people did not have Ebola,” Mr. Moore said.

Public messaging campaigns had urged people to report for isolation and testing if they developed symptoms, to avoid infecting their families.

Instead, Mr. Moore said he saw sick and dying people sheltered in classrooms together with healthy family members. He said there was food and water, but no medicines.

Some patients left. Nurses, who had run out of gloves, did not try to stop them. Mr. Moore watched other people die. He donated several pairs of his own gloves. A delivery of needed supplies arrived just before the violence.

Mr. Tarplah, the nurse overseeing the center, had served in the military during Liberia’s civil war. Ebola, he said, “is worse than the war. The enemy you’re fighting you don’t know. This one is worse than the war.” He added. “In a war, the bullet only strikes one person.”

In Sierra Leone, as the number of contacts with Ebola patients spiraled far beyond efforts to trace them during the 21-day incubation period of the virus, some counselors visited residents at home. Radio programs, posters and even parades were not enough to persuade everybody with symptoms to report to isolation centers, or their family members to refrain from risking their lives to care for them.

“They’re actively rejecting those messages,” not failing to understand them, said Mr. Frankfurter, the Wellbody director. Health care workers, he added, are treating community members “more as disease carriers than as humans with families” going through an “incredible, devastating emotional process.”

Mr. Frankfurter, who was in Sierra Leone until a week ago, said the number of patients seeking regular medical care at his group’s clinic in Kono had dropped to around 10 a day from more than 75, most likely because of fear. Before the crisis, the local government hospital lacked running water, had only recently obtained rudimentary electricity, and was understaffed and frequently out of drugs. While disasters often cause medical standards to slide, recovery from this one, he said, will require higher standards.

By contrast, in Guinea, where the first cases appeared, the outbreak is “more under control than not,” said Dr. Frieden, the C.D.C. director.

Better outreach is helping, said Aliou Boly, who manages Ebola operations for the International Federation of Red Cross and Red Crescent Societies in Guinea. “They know about Ebola in the rural areas,” he said.

To build trust and dispel cannibalism rumors, which stem from families’ inability to bury their loved ones’ contaminated remains or even to see the bodies, some Red Cross workers invited families to watch burials at a distance or even to put on gowns and view the bodies of family members who had died. “This person can use his mobile phone to take pictures,” Mr. Boly said, identifying the corpse and showing that “nothing has been cut out by these people.”

He added that there was a need for psychologists to help families cope with trauma.

Ms. Vaughn, with the Heartt program, said she hoped that trained infectious-diseases doctors and C.D.C. experts would help bring the outbreak under control and create mechanisms to protect health workers. That would allow her organization to convince American universities that their medical residents can safely return to Liberia. “We’re not there yet,” she said. “Right now, we’re still in crisis mode.”