— The two girls had nursed their mother as she died, cleaning up her vomit and curling up against her feverish body on the family’s only mattress. They braided her hair until a truck came for the corpse.

Now, as Ebola leapt from house to house in this sprawling slum, it seemed inevitable that Princess, 13, and Georgina, 12, would soon come down with the disease themselves. Unless someone intervened, they would be the next links in an endless chain of transmission that was destroying New Kru Town.

It was Bobby Pomney’s job to intervene.

Pomney is a “contact tracer” for the Liberian government. When he arrived on a sweltering morning earlier this month, Mary Nyanford’s body was being driven away. Princess was screaming for her mother. Tears were running down Georgina’s cheeks.

“These girls need to be isolated,” said Pomney, a slim, bald man, sweat beading on his forehead.

There may be only one way to halt the worst Ebola outbreak in history: find the disease’s victims, strictly quarantine them and monitor everyone with whom they interacted.

When Thomas Eric Duncan tested positive for Ebola in Dallas, U.S. authorities dispatched a team to identify everyone with whom he might have made physical contact. In a few days, they created a list of more than 120 people. Another team found 142 people who had contact with Amber Vinson, a nurse who became infected. Those measures appear to have kept Ebola from spreading in the United States.

But doing contact tracing and enforcing quarantines in a place like New Kru Town is a different story. Everything here is shared: mattresses, toilets, food, the burden of caring for the ill. Pomney, 43, was from a slum himself, and he knew the odds he would face as he kept watch over the two little girls.

Or at least, on that Monday morning, he thought he did.

New Kru Town is a maze of sheet-metal shanties built on a small peninsula, about a mile long and a half-mile wide, that juts into the Atlantic. Depending on whom you ask, the population is 20,000 or 50,000. It’s a place with open sewers and swarms of mosquitoes that seems as if it was constructed to facilitate the spread of disease. It is an overwhelmingly difficult place to do contact tracing.

“I know this is my job,” Pomney would later say. “But I don’t think it works here.”

Tracking the risks

The day after Mary Nyanford’s body was carried away, Pomney returned with a clipboard and rain boots. He started writing down the names of people who had had physical contact with her while she was sick.

First came her daughters, Princess and Georgina. Their father, a security guard, had been sent to an Ebola treatment center weeks earlier, and the girls were left to take care of their mother when she became ill and refused to go to a hospital.

Within an hour, Pomney had written the names of eight people.

“But there are really around 30,” he said, “or maybe more.”

Some people he visited wouldn’t give their names. Others denied that they had been around Nyanford, apparently to avoid being ordered into the 21-day quarantine, even though it wasn’t enforced.

“You all want to quarantine us, but how we going to eat? How we going to pee?” Cleo Tobar asked.

Perhaps there was reason, though, to be hopeful about the two girls. The disease had been raging across Liberia for seven months. The girls had heard what it could do to a person’s body. They had listened to warnings on the radio. They had seen billboards that pronounced, “Ebola is real.”

In her sixth-grade class, Princess had been taught by her teacher, Mr. Ballah, that “you can’t touch each other anymore.” A community health worker distributed latex gloves in the area. When her mother got sick, Princess slipped on a pair.

“It was to be safe,” she explained later.

But the gloves eventually became dirty. And when her mother got really sick, Princess forgot about them.

The day after their mother died, the girls’ eyes were glassy. Pomney couldn’t tell if it was from crying or something else. He looked at the girls. He wondered if the symptoms were starting to show.

“You got a fever?” he asked.

Both girls offered a muffled no. But Pomney didn’t have a thermometer. No one did in New Kru Town. If the girls were infected, they would probably become contagious long before they were sent to a hospital. It made the quarantine critical.

Pomney rattled through a list of what the girls had to do.

“You guys need to stay here. You can’t play or run around for 21 days,” he said. “My aim is to get you early treatment if you’re sick.”

The girls looked at the ground and nodded.

Pomney thought he had covered everything. He never thought to ask them where they had stayed the previous night.

A U.S. cargo vessel carrying thousands of tons of Ebola relief supplies docked at the Liberian port of Buchanan, part of the United States’ efforts to combat the deadly disease. ( / AP)

Rules and reality

In a health professional’s world, this is quarantine: No socializing with other people. No sharing food. No sharing a bathroom. Ebola is spread through the bodily fluids of highly infected people, and their vomit, urine and mucus can accumulate in bathrooms.

This is the world of Princess and Georgina: They share an outdoor toilet, without running water, with 25 other people. In their slum, 15 members of an extended family often sleep in one home. As for their shack, it had been locked by the body-collection team after their mother’s body was removed, a precaution to keep people away from infected items. The team had also burned the family’s mattress.

So the girls had spent the previous night with their grandmother, who lives across the unpaved alleyway. She, too, had Ebola.

Pomney didn’t know this until someone pointed to the shanty and said, “They got a sick person in there.”

Pomney looked at her through the doorway. The girls’ grandmother, Miriam Nyanford, had covered her naked body with a bedsheet and was breathing heavily. On the wall someone had scrawled, “The Blood of Jesus Must Prevail.”

“You all didn’t call an ambulance?” he asked members of the family who had gathered in front of the house.

“We called one but it never came,” a man said.

Pomney called an ambulance from his cellphone. He turned to the girls, who were sitting in chairs outside their home and using sticks to draw in the dirt.

“That’s indirect contact,” he said, exasperated. “You can’t be staying with her.”

“Where else they going to sleep?” a neighbor asked.

Scientists use formulas to map Ebola’s transmission vectors and its exponential infection rate. But New Kru Town is a place where you can watch the virus’s web grow outward in real time.

Every day that Pomney returned, he was approached by someone reporting a new case: a corpse that had been left on a mattress for three days until it started to decay, the body of an 11-month-old boy, a young man with a high fever who sat zombielike in front of his house.

“This whole area is infected,” he said.

Pomney was left with hardly any contacts to trace, except for the two little girls whom everyone watched, waiting for symptoms to emerge.

‘Pampering, not hardness’

On the third day of their quarantine, the girls played hopscotch with friends on a patch of sand between homes. They played checkers until Georgina got bored. They played with a little dog. They spoke about their mother.

“My mom bought me whatever I wanted. She bought me clothes,” said Princess, who wore a pink sundress.

“She bought me food,” Georgina said, “any kind of food I liked.”

They had heard about Ebola on the radio and in school, but it remained a mysterious, alien force. The men in moon suits aren’t health-care workers, they’re ghosts, Princess said. Ebola isn’t just a virus, it’s an evil spirit that takes over your body. To the girls, quarantine wasn’t a public health precaution, it was something that might leave you alone and hungry.

And being alone was a terrifying new possibility. Since her mother died, Princess had had the same dream: She’s washing her feet in front of the family’s house when her mother suddenly appears. Her mom starts running, and Princess chases her through the sandy streets of New Kru Town. When Princess wakes up, it’s the middle of the night and she’s lying on the floor.

Princess and Georgina continued to sleep in the same rooms as their friends and relatives, and sat in large groups, sharing oranges and cookies.

“These girls are supposed to be in quarantine, but they’re running around with other children,” Pomney screamed when he arrived to check on them one morning.

“Everyone here is going to get infected,” he said.

Then, almost on cue, someone came up to him.

“Bobby, we got a sick person over here,” the man said.

Pomney sighed and walked to the home pointed out by the man. Another member of the contact tracing team, John Shagbeh, joined him.

When they got to the house, a few yards from where Mary Nyanford had died, a man in his early 20s was sitting with a hoodie covering his head, staring blankly.

“This guy needs to go to the hospital,” Shagbeh said.

“We went to the doctor. He said it’s yellow fever,” the man’s mother said.

The contact tracers didn’t believe her. Many people in New Kru Town are desperate to avoid Ebola treatment centers, which they see as dangerous.

“If you don’t go to the hospital, we will call the police on you,” Shagbeh shouted. “You need to accept that this man is infected.”

A crowd had gathered. Shagbeh and the sick man’s mother continued shouting at each other while the man with either yellow fever or Ebola sat in his sweatshirt in the 100-degree heat.

Then a man from the local UNICEF team, Chris Dassen, arrived.

“These people need pampering, not hardness,” he said to Shagbeh. “We don’t need the police.”

Shagbeh walked away.

“There’s nothing the government of Liberia can do to enforce this quarantine,” he said.

An overwhelmed system

In Nigeria, where there were 20 confirmed or probable cases of Ebola in July, tracers created a list of 894 contacts of the patients, and isolated and monitored them. Health workers conducted 18,500 face-to-face visits. Last week, the country was declared Ebola-free.

Now, in New York, officials are scouring the city to find anyone who might have had contact with Craig Spencer, a doctor, since he came down with the disease.

“The way to stop Ebola in its tracks is contact tracing,” Tom Frieden, the head of the Centers for Disease Control and Prevention, said this month.

In the United States, four people have fallen ill with Ebola.

But in Liberia, where more than 4,600 people have been diagnosed with the disease since March, improvised contact tracing teams were formed only after Ebola had spread widely. There could be tens of thousands of contacts scattered across slums like New Kru Town.

The country’s public health system was almost nonexistent even before Ebola. In the United States, many contact tracers have advanced degrees in public health. In Liberia, they are former students or shopkeepers or security guards. Until June, Pomney sold stationery.

Liberia’s contact tracers are supposed to make daily checks on victims’ friends, relatives and neighbors, beginning as soon as the cases are identified. But in New Kru Town, the tracers said, it typically takes about 10 days before the process even begins. By that time, more people have typically developed symptoms.

Some days, no one came to check on Princess and Georgina. The girls walked around the area freely. They played with a headless Barbie doll in front of their home, where a flier on the wall advertised a lottery.

“Your American dream starts here,” it said. “Win and live in the USA.”

A survivor’s struggle

Five days into their quarantine, the girls’ father suddenly returned. He was skinny and weak, wearing tattered clothes. He struggled to speak above a gravelly whisper.

He held a piece of paper bearing the letterhead of Doctors Without Borders, a nonprofit group treating Ebola victims.

“Nyanford Christopher has recovered from the Ebola Virus and is no longer infectious,” it said.

But there was no celebration. Nyanford learned that his wife had died. He learned that his mother was now in the hospital and his daughters had nowhere to sleep. He sat on the stoop of his home and hung his head.

Then he looked at Princess and Georgina, sitting next to him.

“I cannot conclude if they are okay or not,” he said.

Nyanford forced open the door of his home that the body-collection team had locked. He saw the burned mattress.

“How I am supposed to take care of my family now?” he asked.

In the shack next door, the body of his sister, Alice Jallah, had been lying in a room for two days. The ambulance still hadn’t come. The family had locked the room but left the radio on inside, with the corpse.

That morning, through the thin metal walls, a public-service announcement blared into the ravaged neighborhood.

“Wash your hands with chlorine and report all cases,” the man’s voice said. “If we do these things we can prevent ourselves from getting Ebola.”

‘A matter of time’

“How are you coming on?” Pomney asked the girls, six days after their mother died.

Each morning when he showed up in New Kru Town, he expected that it would be the day they started showing symptoms. But again, the girls said they were doing fine. There were no clear signs that they had contracted the disease.

It was Sunday, and the voices of church choirs rose above New Kru Town. The sermons were all about the spread of Ebola. Some pastors blamed the government for responding so slowly. Others blamed the people for refusing to take sick relatives to the hospital.

“You can’t quarantine people here. We’re all intertwined,” said Aloysius Nimely, the pastor of Garden Street Temple Bible Wheel Church.

As families attended church services, Pomney was running between houses. In three hours, he had heard about three new bodies. His job is not to remove the dead, but he was the only representative of the Liberian government in the slum, and he decided he had to do something.

He called the body-collection team. He waited with the families. He took out his clipboard and tried to diagram the web of physical contacts orbiting the deceased. Each time, he got a few names, and then he gave up. The circles were too wide. There were too many people who didn’t want to give their names or didn’t want to admit that they had had contact with the dead.

Exactly one week after Mary Nyanford’s body was driven away, Pomney walked by Princess and Georgina, who were sitting in a circle with relatives.

“It’s only a matter of time,” he said. “One day, they’re going to get it.”