For the doctors, nurses and epidemiologists from the Centers for Disease Control and Prevention who landed in Dallas this week, it all boiled down to this: Who had contact with Thomas Eric Duncan, the first person in this country to be diagnosed with the deadly Ebola infection, and who might have had contact with him? In other words, it was all about information.

First up was interviewing Duncan, known in CDC investigative parlance as the “index subject.” Then the 10-member team led by infectious disease expert David Kuhar began where most information-gatherers begin — by making a list. Actually, by making two lists. One included the names of the people with whom Duncan might have had contact in his two visits to Texas Health Presbyterian Hospital. The other list — well, it included everyone else.

They divided themselves into two teams. Those creating the hospital list took up residence in a human resources office on the eighth floor of Texas Health Presbyterian Hospital. Pediatrician and epidemic intelligence officer Matt Karwowski was assigned to the community list. He and his team holed up in a first-floor conference room in the Fogelson Forum, next to the main medical building.

Three CDC investigators and one county epidemiologist would visit each home on the two lists and interview every person in every household who might have come in contact with Duncan.

The visits began early Wednesday afternoon, according to Karwowski, who was reluctant to say exactly how many homes he visited the first day. He did say, however, that the handful of homes included multiple residents.

CDC Director Dr. Tom Frieden spoke at a news conference Saturday addressing concerns regarding CDC's readiness to fight Ebola and why the U.S. hasn't stopped allowing people traveling from West Africa from coming in. (Centers for Disease Control)

Since Wednesday, most of their days and sometimes nights are spent visiting these “contacts.” They don’t wear any protective clothing. No masks or gloves, and all households on their list are checked on in-person daily.

“At each house we spend as much time as necessary with the potential contact,” Karwowski said. “We’re very careful to do education around Ebola — symptoms, how (Ebola) is spread. We review activities, contacts. Every little detail helps us pin down a person’s risk level.”

Although all the CDC staff on the ground have laptops and cellphones at the ready, their chief tool in contact tracing is decidedly low-tech: a notebook.

The famous green 8x10 hard-bound notebooks are used in every outbreak, and are especially prized because the pages cannot be torn out easily and therefore lost.

But with little time to pack and get to Dallas on Tuesday evening, most of CDC staff traveling to Dallas weren’t thinking about office supplies. Instead, on the first day in Dallas, CDC communications director Dave Daigle suddenly found himself without anything to write on. No problem. Karwowski handed him a slightly smaller, less distinguished hard-bound black notebook. The young medical officer had thought to take extras along.

A little more than three months ago, the 34-year-old Boston pediatrician began a two-year stint at the CDC as an epidemic intelligence service officer. An environmental studies major in college, Karwowski jumped at the opportunity to combine his two loves: medicine and public health.

On Sept. 1, he began full-time work with the CDC’s efforts to contain the Ebola epidemic in Africa. Dallas was his first field assignment.

There were a number of goals for the in-person interviews and home visits, he said: First, they needed to figure out if the people on the list truly had come in contact with patient zero, and if so, what their level of risk was for developing Ebola. Second, they needed to assess the health of the individuals by taking their temperatures and asking them a series of questions about possible symptoms. And third, they knew they needed to educate, reassure and empathize.

“We want to make sure we’re getting the best possible information,” said Karwowski, “so we have to make sure they understand why we’re doing this, and that they trust us and understand that we’re doing this not only for the safety of the public, but because we’re concerned about them.”

The challenges, he said, have been myriad, sometimes involving language and cultural barriers, other times correcting misperceptions about how Ebola is spread. Never did he feel the information wasn’t wanted.

When asked if anyone had refused his team entry into a home, Karwowski vigorously responded.

There was “no resistance from anyone whatsoever,” he said. “Coming into the situation, I found this unprecedented.”

“At every single door, people welcomed us in. They were very compliant, very motivated for a good outcome,” he said. “They were also fearful, but not of us.”

Karwowski said the CDC teams have been working 18 hours a day. When they are not on the phone or in the field they are sharing notes and updating information. The at-risk list has been whittled down to about 50, with only about nine now categorized as at the highest risk level. For Karwowski and the others, it’s all about the information.

“By identifying contacts early on and following them for a 21-day period, we interrupt the chain of transmission, and that’s the most effective strategy,” he said.

But it’s also about the people. As he staggers into bed every night, usually around 2 or 3 in the morning, he says his thoughts turn to the people he’s visited during the day. “I think about what they might be feeling and what they need so we can do everything we can to support them.”

In the morning he will begin making notes again, but these thoughts tonight he won’t put in his notebook.