The main thoroughfare bisecting the town of Faranah, a ramshackle regional capital of 80,000 in central Guinea, is a bustling commercial carnival. Threadbare umbrellas shade vendors and their wares: live chickens tethered to cages made of twigs and twine; heaps of T-shirts and flip-flops; racks of soccer jerseys and flowing boubou garments; stacks of used tires in sizes from moped to tractor; mobile-phone charging stations consisting of power strips puzzled together atop card tables and electrified by portable generators; repurposed soda bottles holding gasoline-ethanol mixtures in hues from fruit punch to orangeade to apple juice. Grimy bills pass from hand to hand: 1,500 Guinean francs for a sweet potato, 2,000 for an onion, 5,000 for a SIM card, 8,000 for a liter of gasohol, 9,275 for a kilo of rice, 45,000 for a live chicken. According to 2012 figures from the government’s bureau of statistics, the most recent available, a troubling 55 percent of Guineans survive on less than 8,815 francs, or $1.20, a day, and the average per capita daily income nationwide is just over $3.

During the week I spent in Faranah, cars passed only occasionally, mostly harlequin taxis of multicolored metal patchwork held together and onto the chassis with duct tape and plastic string, crammed with passengers, roof loads doubling their height. Motorbikes jostled by, honking shrilly as they slalomed around young men in western clothes strolling with friends, their fingers or arms linked affectionately. A few of the women were covered in hip- or full-length black chadors. Eighty-five percent of Guineans, and nearly all residents of Faranah, are Muslim, but only a small minority follow conservative imams. Most women wore snugly tailored sets of blouse, long skirt and head wrap in matching patterns, or T-shirts over wrapped skirts of printed pagne cloth, some decorated with the portrait of President Alpha Condé, from fabric distributed free during his recent successful campaign for re-election. Images of him, wearing a blue suit and dignified expression, were everywhere, on children’s shirts, on posters and fliers plastered onto signs and shop walls, on peeling billboards bearing his slogan: “Progress in Motion.”

It was just 100 miles south of here, in a village called Meliandou near the Sierra Leonean and Liberian borders, that the Ebola epidemic began in December 2013. More than 28,600 people were infected, and more than 11,300 people died over the two years that followed. Guinea, which is more than double the size and population of Sierra Leone or Liberia, the other two hardest-hit nations, had a difficult time stamping out the virus and was the last to be declared “Ebola free,” in late December 2015. In each country, the virus has flared again, most recently in Guinea, with eight deaths in March 2016 alone.

The fatality rate in the Faranah prefecture was extremely high. Eighty-four percent of the 62 reported cases died, and almost half died at home rather than in a medical facility. The nearest Ebola treatment center was a five-hour drive away, and there were widespread rumors that the centers were actually covers for human experimentation, or that Condé had manufactured the epidemic as a ploy to draw international aid money. The rumors about Condé took hold around Faranah even though the president comes from the same Maninka ethnolinguistic group as the region’s inhabitants, which would typically assuage their skepticism. But faith in the government, which has long been plagued by incompetence and corruption, was already fragile, and the fear and misunderstanding around Ebola shattered it entirely. In Faranah, a mob of several dozen angry residents attacked the maternity center, which was being used as a base for the Red Cross. They defaced the facility, destroyed equipment and set fire to a Doctors Without Borders vehicle parked outside. Nationwide, Guinea had a much higher fatality rate (66 percent) than Liberia (45 percent) or Sierra Leone (30 percent) — in part probably because of the population’s determined avoidance of medical support.

Even if citizens had trusted the government medical workers enough to seek care, the country’s feeble health care system would have had little to offer them. The government of Guinea devotes only 2 percent of its gross domestic product to health care, amounting to about $12 per person in 2013. That figure would need to be closer to $44 to support a bare minimum of “basic lifesaving services,” according to the World Health Organization, and the country has among the worst maternal-, infant- and child-mortality rates in the world to show for that gap. Ten percent of children die before the age of 5, and nearly a third die before 15, most from malaria, diarrhea or pneumonia. Many villages have no trained health workers, and sick or pregnant patients must travel long distances on foot to access even rudimentary care at a health outpost — usually just a bare room with an auxiliary nurse who has little more than malaria test kits and some training in assisting childbirth. Even the largest hospitals operate without running water, sanitation, consistent electricity or reliable stores of medications or equipment. The danger of pandemic emergence is highest where the levels of health care infrastructure and resources are low, and 28 other countries around the world struggle with health systems as weak as Guinea’s, or worse.

During the epidemic, Western media outlets focused much attention on the billion-dollar scramble for high-tech medical solutions — vaccines, or antiviral drugs like ZMapp — that are still making their way through clinical trials and certifications. But the initiative that holds the most promise for preventing another epidemic is as rudimentary as they come. The governments of Guinea, Sierra Leone and Liberia, with assistance from the W.H.O. and NGOs, have tried to train all government health workers in a standard set of practices called Infection Prevention and Control (I.P.C.) and provide these workers with the low-tech, inexpensive equipment — soap, wash buckets, hand sanitizer, gloves, masks, long-sleeved gowns — needed to put those practices into effect. It amounts to basic hygiene, with an emphasis on hand-washing, which remains the single most effective practice for preventing the transmission of infectious disease. The I.P.C. trainings in West Africa are adapted for the realities of conditions on the ground, where access to plentiful running water, plumbing, electricity and cleaning supplies is often lacking, and infection-prevention protocols are unfamiliar.

In Guinea, as new cases of Ebola continue to appear, the front-line soldiers in this fight will be the health workers in Faranah and other towns across the countryside. Most did not complete high school, and some struggle with French, the language of higher education in the country. Many serve in communities where literacy rates are less than 25 percent, germ theory is unfamiliar and trust in government is low. Their success in adopting infection-prevention practices and in recognizing symptoms of Ebola and other deadly infectious diseases — and keeping themselves and other patients from spreading them — is crucial to preventing the next dangerous outbreak from becoming another epidemic.

Dr. Sadou Diallo is a slight man, trim and compact with a high forehead above wire-rimmed glasses. He is the director of obstetrics and gynecology at the Matam Community Medical Center, in Conakry, Guinea’s capital. Matam is one of the country’s busiest health facilities, and an average of 400 women deliver there each month. His temperament is suited to the high drama of childbirth: He is preternaturally calm, deliberate and gentle in his movements.

For years, Diallo has been affiliated with an NGO called Jhpiego, originally the Johns Hopkins Program for International Education in Gynecology and Obstetrics. When the Ebola crisis arose, Jhpiego already had a network of Guinean doctors, nurses and midwives ready to serve as “master trainers” for the health system. Their expertise was easily up­graded to Ebola, and the director of the W.H.O.’s Ebola response in Guinea described them to me as providing the “gold standard” of training in the country. Now, when Diallo was not at the medical center, he was conducting I.P.C. trainings around the country as a Jhpiego instructor.

I joined Diallo and his colleagues Dr. Kadiatou Traoré and Kaba Kourtim Saran, a midwife, in Faranah in November at a disused building — basically an empty concrete room — that belonged to the municipal government. Hefty wooden tables and chairs had been arranged in a U shape, leaving just enough space for 13 men and 12 women to wedge themselves around the perimeter. A few Ebola educational posters had been stuck to the walls with strips of masking tape. On one, graphic cartoons depicted a man suffering from each Ebola symptom — bloody diarrhea, fever, bleeding nose and gums, muscle and joint pain, bloody vomiting and skin eruptions — as he is beckoned into a neat, white health post by a welcoming lab-coated caretaker. Another poster depicted ways to avoid infection, with big red Xs over drawings of dangerous situations representing the “don’ts”: a pair of people carrying a corpse; a family weeping and embracing a deceased loved one; a frying pan filled with flesh, which a thought bubble indicated came from a bat, a squirrel or a monkey. Next to the don’ts were the “dos”: the steps of proper hand-washing.

The trainers distributed the basic I.P.C. tools to the trainees seated shoulder to shoulder at the tables: small bottles of alcohol-based hand sanitizer (now affordably produced in-country); folded disposable liquid-resistant long-sleeved smocks; crinkled green crepe bands that unfolded into hair covers; paper masks; latex gloves. About two-thirds of the group were nurse’s aides or health technicians (called agents techniques de la santé, a sort of auxiliary nurse who has completed three years of professional school after the 10th grade). Health technicians are the most common health care provider in Guinea and often the only medical professional in a rural village. The rest of the group were nurses, midwives, doctors and laboratory technicians.

The trainees shrugged their way into the gauzy smocks, helping one another with the sticky tabs behind the neck, then unraveled the bonnets and tucked their hair inside. Diallo walked around the room, face impassive, gauging their level of experience, stopping to offer a few words of correction here and there or demonstrate procedure. He moved with economy, touching materials with just the tips of his fingers, minimizing the surface area of contact.

Elisa, a young midwife from Conakry doing a temporary rotation in a rural health center, confidently peeled open the envelope of sterile, individually packaged gloves, pressing its edges flat to the table. She pinched the wrist of the glove delicately, placed the fingertips of her other hand inside the opening, then slipped on the glove in a single motion, pulling it over the edge of her smock sleeve. The trainee next to her watched her out of the corner of his eye. Failing to recognize the purpose of sterile-packaged gloves, he picked them up in his hand, flipping them around until he picked one, stretched it on over his fist, then struggled to tug each finger into place, pulling at the palm, with no regard for contamination.

“What service do you work in?” Dr. Yolande Hyjazi, the Guinea director of Jhpiego, asked him brusquely.

“Laboratory,” he responded. That is, where handling pathogens is the job.

Traoré began a circuit of the room carrying a small plastic bottle. Onto the students’ gloved palms, she squirted a tablespoon of bright red paint. “Close your eyes and wash your hands,” she instructed from the front of the room. Diallo walked slowly from student to student, waving at them to close their eyes. “Wash like you usually do,” he directed.

Despite its fearsome reputation, Ebola is transmissible only once an infected person is heavily symptomatic. The virus itself can be killed with a simple, thorough scrubbing of hands or surfaces with a chlorine solution or alcohol-based sanitizer; even a careful washing with soap and water can remove it.

The students began rubbing their palms together vigorously, paint smearing over the insides of their hands. Most knew to flip each hand over to scrub the back with their fingers interlaced. But only a few knew all the steps they were expected to complete — cupping the fingers together with one palm up and the other down and rotating the first two joints underneath each other; swirling the fingertips in each palm; grasping and twisting around each thumb and then each wrist. After 30 seconds, Diallo told them to stop and hold up their hands. Dull patches of ivory-colored latex mottled the glossy red paint where they had failed to clean their thumbs, pinkies or the tips or sides of their fingers.

Their next challenge, he told them, was to remove the gloves as if the paint were infected blood, avoiding any contamination. He walked around the room, inspecting their efforts to invert the soiled gloves. He complimented one student who had deftly wrapped one glove neatly into the other. Approaching another, he pointed to a red swipe on his skin.

“You see that? Ebola. And you,” he said, turning to another, “look, come here. You saw this? That, that is Ebola.”

His delivery was deadpan, and nearby students snickered nervously. Traoré and Hyjazi looked at the students Diallo had just reprimanded and burst out laughing. Traoré waved her arms, theatrically warding them off and backing away as Hyjazi pointed. “Watch out,” Hyjazi said. “They’ll give you Ebola!” The room erupted in laughter.

Sadou Diallo didn’t intend to become a doctor. The village where he was raised in western Guinea had neither a middle school nor a high school, not to mention jobs that required them, but his father hoped to provide a better education for his son. He asked a friend, a government bureaucrat in the regional capital of Kindia, to host the boy so that he could continue to attend school. When Diallo’s father died, his guardian, along with his four wives and 14 surviving children, welcomed the 12-year-old as one of their own. They put him through school and university, found him a wife. Diallo excelled in mathematics and intended to pursue a career as an engineer with the mines, the only industry of note in Guinea. But his guardian, a devout man, pushed him toward medicine. He told Diallo it would be a benediction to treat the sick. It would not offer the earthly rewards of mining, but it was better for his community and better for his soul. Diallo acquiesced to the wishes of the man he had come to call father.

On Aug. 25, 2014, Diallo was called into an emergency operation at Matam, where he delivers babies. Earlier in the day, his colleague and former student, Dr. Seyni Guémou, had performed a cesarean on a patient whose baby’s heartbeat had become dangerously slow and weak during delivery. Despite receiving immediate care from a neonatal intensive care doctor, the baby did not survive, and it quickly became apparent that the mother was having complications, hemorrhaging alarming quantities of blood. She was rushed back into the surgery room, and Diallo worked with Guémou and two assistants to stem the bleeding, ultimately removing the woman’s uterus.

“But the bleeding didn’t stop,” Diallo told me as we sat in the cramped staff room at Matam, shaking his head as he remembered his bewilderment. “Her skin itself was bleeding.” It was unlike anything he had seen before.

Only 45 people had died from Ebola in Conakry at that point. Rushing into a life-or-death operation and worrying only about the health of the mother, the surgical team hadn’t thought they might need anything other than their regular kit, a substandard ensemble they fatalistically call “kamikaze”: short-sleeved cotton scrubs, rubber apron, latex gloves, paper surgical mask, goggles, bonnet. It was only while standing next to her body, covered in her blood, that Diallo began to suspect that the mother might have been infected.

He sought out the anesthesiologist, who told him that the woman had presented with a high fever, but she was given antibiotics, and the fever dropped. The matron attending her in the delivery room confirmed that the woman vomited, and experienced diarrhea, but she considered those normal in labor.

Diallo returned to the staff room, which, like the rest of the medical centers in Guinea, did not have running water. He scrubbed a cut on his left forearm vigorously with bleach, then gathered the team to inform them to prepare for the near certainty that all of them had contracted the Ebola virus.

Guémou was the first to fall ill, five days after the operation. As Day 7, Day 10 arrived, more of the team — the three surgical assistants involved in the cesarean or the hysterectomy, the intensive-care doctor who took charge of the baby — developed fevers. On Day 13, Diallo asked his wife to take their four children from their apartment. She settled the kids with family, but returned to his side and refused to leave. He was certain he had contracted the virus. He organized his papers and wrote out instructions for his wife in the event of his death.

Finally, on Day 15, his temperature began to rise. He immediately made arrangements to leave for the Doctors Without Borders Ebola treatment unit (E.T.U.), which had been set up in a huge bare lot next to Conakry’s largest hospital. His wife begged him to wait, to be certain it wasn’t malaria, but he was firm. He asked her to leave the apartment, lock it behind her and stay away until tests confirmed his diagnosis. If he was quarantined, the Red Cross would sterilize the apartment before her return.

He called his driver, informed him that he had Ebola and asked him to bring the car and leave it running, with the door open and the keys inside. He wanted to drive himself to the E.T.U. without putting anyone else at risk. When the driver insisted on taking him, Diallo asked him to open the right rear door, then return to the driver’s seat. As he told me this, he sketched an agitated diagram on a scrap of paper, the rectangle of the car body, with an X in the back corner for him, an X in the opposite front corner for the driver. At the E.T.U. — a plastic village of mud-spattered white tents navigated through a maze of waist-high channels bounded by orange netting that was meant to keep the uninfected from stumbling upon the infected — he made certain the attendants sterilized the car before the driver left. “I contaminated no one,” he insisted.

The worst of the symptoms followed several days later. For five days, he could barely move, even to turn his own body in his cot. He could talk on his cellphone, but if it fell on the floor, he was helpless to retrieve it. Attendants would tuck the phone under his ear, lift him to give him water, food and medication and to clean what he couldn’t keep down.

“It was all these acts that saved me,” he said. In a photograph taken 16 days after his arrival, his shoulders are shrunken, his frame swamped by the red T-shirt he is wearing. There is an IV port in his arm, but he is standing, and smiling weakly. Others from his team weren’t so lucky. Of the six who contracted the virus, the other two doctors and one assistant did not survive. The doctor who had taken charge of the infected infant died on the floor of the E.T.U. as Diallo watched, helpless.

After 18 days, Diallo was released. In the absence of him and his team, hundreds of women who would otherwise have given birth at Matam were left to deliver their babies at home. Women had been calling the center, asking about him. They took his recovery as a sign that the worst was over, and began returning to Matam for his care.

Soon after, he received a call from Dr. Yolande Hyjazi, asking him to consider an active role in Jhpiego’s I.P.C. training for Ebola prevention. Jhpiego’s records indicate that the rate of Ebola transmission to health care workers dropped to 0 to 5 percent from 5 to 35 percent after training. Diallo had seen the impact at Matam, where, after I.P.C. training, the staff recognized and referred a number of pregnant women with Ebola to the appropriate treatment facilities, with no transmission to staff or other patients at Matam. He was eager to assist.

“The concern I have is this: This will not stop repeating,” Diallo told me. “It is endemic here now, like malaria. We must be ready at every moment.” When he travels for Jhpiego, he is often the first Ebola survivor many of the trainees have met. Their vigilance in identifying the signs of the Ebola virus — which overlap with common ailments like malaria — is crucial. He is not shy about using himself as an object lesson in the high stakes of their work, from using Matam’s tragedy to add weight to his lessons. And the students respond, listening a little more carefully, watching a little more closely.

There is one obvious weakness to this strategy of training government health workers: Surveillance and treatment can curb Ebola only if patients seek care in the first place. When most Guineans fall ill, they first visit a local traditional healer, of whom a recent census indicates there are about 80,000 operating in Guinea. Dr. Sakoba Keita, the government’s “Ebola czar” in Conakry, told me that for a West African, even a Muslim one, “his first reflex is his cultural background. He goes to see his soothsayer or his diviner to see what’s going on.” Keita acknowledged that some traditional healers are devoted to helping their communities, but he believes that more are practicing fake healing just to make money, and that too many failed to heed the warnings and instructions about Ebola.

One of the gravest missteps at the beginning of the outbreak led those with Ebola in the wrong direction — i.e., toward local healers and away from medical centers. At that time, authorities, hoping to convey how important it was to follow steps to avoid contracting the virus, stressed that there was no medication and no vaccine. But this message unintentionally suggested that it was futile to seek treatment. (Eventually the government settled on a new message: Early treatment improves the chances of survival.) Authorities are now also trying to increase reliance on health care workers among village residents through a network of “community agents.” These are local residents, one man and one woman chosen by each community, who are being trained to make sure that they have a basic understanding of issues like vaccination, hygiene and childbirth. There are currently 5,800 community agents, and the government hopes eventually to have 18,000. The notion is that these Guineans can serve as trusted sources for their towns, encouraging sick patients and their relatives to turn to the medical system — the same tenuous groups of nurses and assistants that Diallo and his colleagues have been trying to teach.

On the fifth and final day of training in Faranah, the students were exhausted, their attention strained after hundreds of slides and hours of developing action plans. They were draped over one another’s chairs, fanning themselves with papers and conducting sideline conversations in low tones. The fan bolted to the ceiling had no electricity to power it. A goat, tied by its collar in the back of a truck in the yard, crashed around outside the window, interrupting final lectures. It was a Saturday, and the students were eager to finish their exams and get on with their evening plans.

Diallo held up a set of green cotton scrubs. “The nurse who died at Donka during Ebola got it on her skirt. She couldn’t take it off, so she just did like this,” he said, miming wiping his leg. “If you’re wearing scrubs, you can just take it off.” Scrubs — separate clothing for the work of caring for sick people who remain at the health care facility — are another piece of equipment that is still uncommon for many health workers.

He asked six trainees, three men and three women, to come to the middle of the room. He held a stapled checklist. On the ground in front of each student were the elements of a P.P.E., the Ebola-specific personal protective equipment. Donning the equipment, which took the students 25 minutes, is not even the dangerous part. After an encounter with an infected patient, when the caregivers are overheated and exhausted, the exterior of the suit is most likely contaminated.

The stakes, then, are highest during the removal procedure, which reverses the steps. Diallo directed them. He misted the students, front and back, with a chlorine solution between each step. Following his instructions, they placed their right hands on the zipper at the level of their navels, walking their fingertips slowly up to the zipper pull beneath their chins. He corrected them as they went, warning them not to touch their necks with contaminated gloves. Unzipping the suits, they peeled them outward, away from the sweat-soaked clothing now clinging to their skin. They lifted their knees high, trying to extract their legs and boots and shake their skirts back down over their calves without touching the exterior of the P.P.E.

“Dance! Dance! Merengue!” teased Traoré from the corner of the room.

At the end of the day, the trainers gave the students a pep talk and wrote their personal cellphone numbers on a flip chart, encouraging the students to call them anytime with questions or concerns. After rounds of group photos and farewells, Diallo, Traoré and Saran returned to the classroom, taking advantage of the electricity from their portable generator to fill out paperwork and evaluations on laptops. I brought up the new Liberian Ebola cases — two months after the country had been declared “Ebola free” — which had just been identified. The new cases were an unwelcome reminder that Ebola not only persisted in unidentified animal reservoirs, but seemed to be capable, in rare cases, of becoming contagious again in human survivors months after their recovery. Each new appearance of the virus threatened to spark a new epidemic.

Diallo couldn’t disguise a flash of worry, but he reacted to the news with his usual dry sense of humor. He picked up a bottle of hand sanitizer, flipped open the lid and held it out pointedly over my hands.