In two Land Rovers, one fitted out as an ambulance, a small team of humanitarian workers last week headed deep into Sierra Leone's jungle. After hours on deeply rutted paths that could barely be called roads, they stopped at a village that had seen ten reported cases of Ebola.

With the consent of the village chief, the team fanned out across the community, asking at each hut if anyone was feeling ill or had made contact with the earlier patients. At one, they found a mother nursing a 7-month-old, even though she had experienced bouts of bloody diarrhea and a fever of 102°F—possible signs of Ebola. A quick conversation revealed that the mother had recently attended the same funeral as the ten patients.

The aid workers knew right away they had to get the woman away from her village. It would improve her chances of recovery, even though those chances hovered at only about 30 percent. And it would protect her baby and husband, and the entire community, because Ebola is easily passed through bodily fluids such as diarrhea, vomit, and blood. (Related: "Q&A: Challenges of Containing Ebola's Spread in West Africa.")

But that didn't make taking the woman away any easier.

"If you've got a mother crying, her baby crying, her husband crying, her grandmother crying, and the mother in desperate need of medical care, that's a very difficult situation," says Gabriel Fitzpatrick, an Irish infectious disease doctor who helped make the difficult decision to take the mother from her community to an Ebola hospital in Kailahun, a several hours' drive away.

Despite tears, the family didn't put up much of a fight. The terrors of the fever were already well known to the village.

"Nobody wants to split up a family," says Fitzpatrick, who works for the humanitarian group Médecins Sans Frontières (MSF), also known as Doctors Without Borders. But "if you let the mother stay there, the outcome is more people will be infected."

View Images Nursing students in Freetown, Sierra Leone, wait to take their final qualifying exams so they can join the fight against Ebola.

View Images An area near the town of Kenema in eastern Sierra Leone is under quarantine.

In West Africa, where history's worst-ever Ebola outbreak has sown terror in countries with virtually no health care infrastructure of their own—Liberia, Guinea, and Sierra Leone—foreign health-care workers like Fitzpatrick have been an essential part of the response since spring, when the disease began to spread rapidly. (Related: "As Ebola Crisis Spreads in West Africa, Liberia's Deterioration Stands Out.")

The World Health Organization announced this week that another, unrelated outbreak began late last month 1,500 miles (2,414 kilometers) away in the Democratic Republic of the Congo after a pregnant woman ate infected meat. There are 24 suspected cases of Ebola in the northern part of the country, including 13 deaths.

So far the virus has claimed more than 1,400 lives in West Africa—about half as many as are known to have been infected. Entire families have been wiped out. Medical care for other diseases, trauma, and childbirth—scant before the Ebola crisis—has evaporated. In the three hardest-hit countries, there are one or two doctors for every 100,000 people, and most are in cities, according to the World Health Organization.

The disease has struck health-care workers, locals and foreigners, with particular force. At least 240 have fallen ill and 120 have died since the outbreak began last December, according to the WHO.

Such losses "deplete one of the most vital assets during the control of any outbreak," WHO said in a press release this week.

Many more have fled in fear. "The loss of so many doctors and nurses," the press release said, "has made it difficult for WHO to secure support from sufficient numbers of foreign medical staff." (Related: "Successful Marburg Virus Treatment Offers Hope for Ebola Patients.")

International aid workers have been crucial in making up the difference, says Sophie Delaunay, MSF's executive director. The international aid group runs Ebola clinics throughout the affected region, including the 80-bed facility in Kailahun, where Fitzpatrick has spent the last month.

Photographer Samuel Aranda traveled earlier this month to Kailahun, a small town near Sierra Leone's borders with Guinea and Liberia, population 30,000, for National Geographic, shooting portraits of caregivers and photographs of affected communities. "The landscapes here are littered with destroyed buildings and burned houses that were abandoned and looted during the civil war," Aranda says. (Related: "Q&A: Photographer in Liberia's Ebola Zone Encounters the Dead—But Also Moments of Joy.")

He describes the MSF hospital there as well organized, with an incredibly dedicated staff.

On Tuesday, WHO announced it was temporarily pulling its own workers out of Kailahun, after one became ill with Ebola.

Médecins Sans Frontières has received a small but steady flow of volunteers from Europe, the United States, Canada, and Australia, as well as other nations. "I’m surprised to see the number of people who really want to put their expertise at the service of our patients," Delaunay said in an interview, “and who actually are ready to stand by the patients."

More trained medical staff are desperately needed, largely to relieve those already worn out by the battle, Delaunay says. But she wants only volunteers who understand the dangers Ebola presents and who know how to work safely with protective gear. Anyone who doesn't can quickly get infected—and pass the disease on to others.

Giving Care, Taking Care

Respect for the virus—also known as fear—is constantly top of mind among aid workers. Geraldine Begue, a nurse from Luxembourg now working in Kailahun, said she's grateful for it. "It keeps you concentrated. You should not lose that fear," says Begue, who lives in Fribourg, Switzerland. "If you stay concentrated you can keep yourself safe."

View Images *Suspected, probable, and confirmed cases and deaths as of August 20, 2014. Democratic Republic of the Congo data as of August 26, 2014. *Suspected, probable, and confirmed cases and deaths as of August 20, 2014. Democratic Republic of the Congo data as of August 26, 2014. DANIELA SANTAMARINA AND KELSEY NOWAKOWSKI, NG STAFF. SOURCE: WORLD HEALTH ORGANIZATION

Kent Brantly and Nancy Writebol, American volunteers for Christian missionary groups in Liberia, fell ill with Ebola in July and were flown to Atlanta, where they were treated at Emory University Hospital. Both were released last week and are considered cured.

WHO has not announced any details about its sick worker. No other western caregivers have been confirmed ill, but a Spanish priest ministering to patients died shortly after returning home, while a Liberian-American died after traveling to Nigeria, where he transmitted the virus.

The precautions sound simple enough; if workers avoid contact with patients' bodily fluids by wearing protective suits, goggles, masks, and gloves, and by cleaning up thoroughly, there is no risk of catching the virus, Begue and others said. Just to be safe, Médecins Sans Frontières prohibits all physical contact with patients or others at the treatment center without protective gear.

"You have very intense moments and you want to hug someone and you can't," Begue says. She connects with patients the best she can through empathetic eye contact, as her eyes are the only part of her they can see through her protective goggles.

View Images A woman and her baby sit near a quarantine checkpoint in eastern Sierra Leone under a poster showing the symptoms of Ebola.

View Images Siblings Gina and Tike Lami, both suspected of being infected with Ebola, arrive at a field hospital in Kailahun, Sierra Leone.

View Images A Red Cross worker puts on protective gear before entering the house of a suspected Ebola victim in Gbeka, Sierra Leone.

The suits are so stiflingly hot that no one can stand to be in them for more than an hour or two. And Begue can't spend much time with any one patient because there are so many more to treat. "There's never enough time," she says.

Begue's workday starts with running blood tests on patients admitted the day before, and on those who have been symptom-free for four days, who hope they'll be cleared to go home. Then she puts on protective gear so she can bring patients needed fluids, which she says is "the only thing that really helps them."

After that, she and her colleagues might restock the pharmacy and check on gear.There are no approved treatments for Ebola, although Writebol and Brantly received two of the five courses that have been dispensed to date of an experimental treatment called ZMapp, which seemed to have helped. For everyone else, the best care mainly involves replacing fluids depleted by vomiting and diarrhea, stabilizing blood pressure, and reducing fevers.

Begue's afternoons are spent waiting for lab results, "who is going to be admitted, who is going to get out, who is negative."

Next comes triage, the hardest part of Begue's day. She has to talk to patients, often through a translator, and gain enough trust that they'll tell the truth. "Patients keep lying to us," she says. "They don't see the point to telling us everything."

Some will say they don't know another patient, and it will turn out they are siblings.

Discerning whether a fever is due to Ebola or some other malady like malaria is another daily challenge. Every evening, Begue and the other nurses send some people home, hoping they have diagnosed them correctly as sick with something other than Ebola. Then they take blood samples from the people they suspect of having Ebola.

What scares her more than Ebola patients, Begue says, is her colleagues: "If someone else is not that careful—if someone makes a mistake and you don't know it, and he doesn't know it, he might give you Ebola."

The most dangerous time comes when the protective equipment is taken off. Simply touching the outside of a gown or goggles might be enough to transfer the Ebola virus to someone's skin. If the virus gets into the body through a cut, the eyes, or another orifice, it can wreak devastation.

Dozens of workers share the same eating areas, kitchen, and hotel space. "You never know how safe they have been," Begue says.

Harder still is accepting the reality that so many won't make it: "You know that less than 50 percent [of the patients] are going to survive."

Malcolm Hugo, a psychologist at the same Kailahun facility as Begue and Fitzpatrick, says he tries to make sure nurses break bad news to patients as gently as possible. Patients need time to adjust to the terrible diagnosis.

They also need help obtaining basic necessities, such as toothbrushes and clothes to wear while they're away from home. They need to be told exactly what will happen to them. And they need access to cell phones, so they can deliver the bad news to relatives and friends.

Hugo, of Adelaide, Australia, also counsels children and adults who may be the only survivors in an extended family.

Many have "intrusive thoughts, distressing memories, trouble sleeping" he says—the hallmarks of post-traumatic stress disorder. Some who survive the disease must cope with stigma when they go home. Family and neighbors often reject them, thinking they're still contagious, or that they'll bring bad luck.

Keep Coming Back

Yet Begue just re-upped for another month of duty. And Fitzpatrick, who's also been in Sierra Leone for a month, says he'll stay until the emails from his wife get longer and nastier. "Once the emails reach two pages, you know it's time to look at some airline tickets," he says.

Both say that they can cope with the tragedy and stress because they know they're making a difference. Begue quit a regular nursing job a few years ago and now goes on missions full-time; Fitzpatrick tries to make it on one mission a year in addition to his work at the Health Protection Surveillance Centre in Dublin.

View Images The body of 60-year-old Hauwa Ansmana, an Ebola victim, is carefully removed from the family home in Gbeka.

View Images Onlookers mourn the death of Hauwa Ansmana, 60, an Ebola victim in Gbeka.

View Images Red Cross workers bury the body of a suspected Ebola victim in a remote area in the bush.

View Images Aid worker Luca Zaliani, from Milan, Italy, grieves after losing three patients to Ebola at a field hospital in Kailahun.

"If someone wants to feel useful, this is the place to be," Begue says.

Without them and their colleagues, the patients would have far less chance of survival, and the virus would spread even farther than it has, Begue and Fitzpatrick say.

Deborah Eisenhut has another reason to put herself in harm's way: God. An Oregon native, Eisenhut has been a missionary doctor for seven years with the Christian group called SIM. "I feel that my faith gives me the purpose and the tools and the hope I can give people," she says.

Now in the United States, she hopes to return to the missionary hospital she ran for 16 months in Liberia's capital, Monrovia, before the end of the year. She was ordered home, along with all her colleagues, after some members of her mission were threatened and after Nancy Writebol, also of SIM, became ill. The Liberian government took over the hospital in late July.

It's hard, she says, knowing the suffering continues and that she can't help right now.

"You can't emotionally take on the responsibility for all of it," she says. "You do what you can do and let God deal with the rest."

That international aid workers can go home while locals have no escape is part of the reality of humanitarian missions, Begue and Fitzpatrick say. "It's bizarre that you can leave this place and leave them all here, and go back to your family and friends," Begue says.

Going home and getting a break is essential in humanitarian care, and MSF won't allow anyone to stay for more than six to eight weeks at a time. Caregivers who get worn out are more likely to make mistakes, infecting themselves and those around them.

That's why the international workers are housed in a hotel and are well fed. "If we slept ten in a tent," Begue says, "you could not rest and that would not help the mission."

What does help the mission are the success stories, the Ebola patients whose bodies manage to fight off the disease. Four days after the virus is no longer detectable in their bloodstream, they are allowed to go home.

The week before he had to take the mother away from her baby, Fitzpatrick accompanied a recovered 19-year-old girl back to her family.

Humanitarian workers always bring these patients home, rather than allow them to go alone. They shake the recovered patient's hands to show that they're not afraid, and give them a certificate verifying that their illness is over. These signs, they hope, will overcome any community reluctance to accept the patients back.

In this case, Fitzpatrick says, the woman's family was welcoming—and thrilled by her survival.

"Her grandmother and her mother and sisters were crazy with happiness, dancing, singing," he says. "It was a very happy moment to see that emotion. It's very rewarding."

View Images Red Cross members dress in personal protective equipment before entering the house of a suspected Ebola victim in Gbeka.

View Images Members of the Red Cross spray each other with chlorine after removing the body of a suspected Ebola victim from a house in Gbeka.

View Images Local medical staff take a much-needed break at a field hospital in Kailahun that’s run by Médecins Sans Frontières.