The hospital that treated Ebola victim Thomas Eric Duncan had to learn on the fly how to control the deadly virus, adding new layers of protective gear for workers in what became a losing battle to keep the contagion from spreading, a top official with the Centers for Disease Control and Prevention said Tuesday.

“They kept adding more protective equipment as the patient [Duncan] deteriorated. They had masks first, then face shields, then the positive-pressure respirator. They added a second pair of gloves,” said Pierre Rollin, a CDC epidemiologist.

Despite the infection-control efforts, a nurse, Nina Pham, 26, somehow contracted Ebola at Texas Health Presbyterian Hospital Dallas while caring for Duncan, a Liberian man who flew to the United States last month. Pham is being treated at the same hospital, and Tuesday she was reported to be in good condition. (On Wednesday, state officials announced that a second worker who cared for Duncan had also tested positive for the virus.)

CDC Director Thomas Frieden expressed regret Tuesday that his agency had not done more to help the hospital control the infection. He said that, from now on, “Ebola response teams” will travel within hours to any hospital in the United States with a confirmed Ebola case. Already, one of those teams is in Texas and has put in place a site-manager system, requiring that someone monitor the use of personal protective equipment.

“I wish we had put a team like this on the ground the day the first patient was diagnosed,” he said. “That might have prevented this infection.”

Widespread concerns for Ebola epidemic in the United States

In the Duncan case, the CDC sent disease detectives to help track down people who might have been exposed, but the agency largely let the hospital handle its own infection control.

At least 76 workers were potentially exposed to Duncan in the hospital before he died Oct. 8, and they are being monitored daily for any signs of fever or other symptoms.

In one positive development, the 48 people who were potentially exposed to the virus by coming into contact with Duncan before his Sept. 28 hospitalization — including his fiancee — have remained symptom-free for more than two weeks and are close to being in the clear. The incubation period can in theory last as long as 21 days, but usually the symptoms flare within the first two weeks.

From the beginning of the Ebola crisis, disease experts and Frieden in particular have insisted that U.S. hospitals have the training and equipment to handle a highly contagious patient. On July 21, Frieden said that “Ebola poses little risk to the U.S. general population.” Any advanced hospital in the country has the capacity to isolate a patient, he said. “There is nothing particularly special about the isolation of an Ebola patient other than it’s really important to do it right,” he said at the time.

But the revelations this week suggest that Texas Health Presbyterian Hospital was not fully prepared for the unfamiliar virus and had to adjust its protocols as Duncan’s illness progressed. The hospital did not respond to a request for comment.

The CDC’s Rollin, who spent nearly three months in West Africa fighting the Ebola outbreak, and who has studied Ebola for three decades, flew to Dallas on Sunday and held intensive discussions with doctors and nurses at the hospital about how they had handled the Duncan case.

He said the hospital originally had no full-body biohazard suits equipped with respirators but now has about a dozen. Protocols evolved at the hospital while Duncan was being treated, he said: “Collecting samples, with needles, then you have to have two people, one to watch. I think when the patient arrived they didn’t have someone to watch.”

How quickly Ebola spreads compared to other diseases

He said CDC specialists, along with two nurses from Emory University Hospital, are training health-care workers at the hospital. Rollin described the elaborate methods for removing waste from a room: Bag the trash and disinfect with bleach wipes. Put it in another bag and disinfect that bag. Then a buddy outside comes to the door with another bag into which the waste is deposited. That third bag is also disinfected. Then the trash is put in a cardboard container lined with a heavy-duty plastic bag, and that is taken outside of the unit by a contracted biosafety company that transports it to an incinerator.

“It’s a race between you and the virus, but the virus has a head start,” Rollin said.

How the nurse contracted Ebola remains a mystery.

“I’m doing well and want to thank everyone for their kind wishes and prayers,” Pham said in a statement released by the hospital.

In a conference call with journalists late Tuesday, the labor organization National Nurses United read a statement that it said came from nurses at the hospital who “strongly feel unsupported, unprepared, lied to and deserted to handle their own situation.”

The statement alleged that guidelines for handling the Ebola patient were constantly changing, and that for two days after Duncan was admitted to isolation the nurses were given personal protective equipment that left their necks exposed. The organization did not name the nurses or say how many contributed to the statement.

Only four facilities in the country are specially designed for Ebola-type cases, including one at Nebraska Medical Center, where two people who contracted Ebola in West Africa have been treated. Mark Rupp, chief doctor for the center’s infectious-diseases division, said Tuesday he has received “countless” calls from health professionals worldwide who want to replicate Nebraska’s infection control procedures.

According to Rupp, the secret is simple: meticulous attention to detail.

First, health-care workers enter the “clean” locker room with scrubs, a mask and a pair of gloves. When they enter the “hot zone,” they don more protective gear: shoe covers, a second pair of gloves, an impenetrable full-body gown, a hood that covers the head and neck, a fitted respirator with a transparent shield.

An observer with a checklist monitors how workers put on and take off their equipment.

“It’s easy to make mistakes when you take off your gear,” Rupp said.

The Ebola news in the United States came amid warnings from the World Health Organization that the disease is spreading to new areas in West Africa and is still rampant in the capital cities of Liberia, Sierra Leone and Guinea.

Without a strong response, the virus could be infecting as many as 10,000 people a week in West Africa by Dec. 1, said Bruce Aylward, the WHO assistant director general who is overseeing the organization’s response to the epidemic.

He noted some signs of progress. Several of the original centers of the outbreak in Liberia and Sierra Leone have seen a drop in new cases, and this is the result of a “real change in behavior,” including changes in burial practices, Aylward said.

But the nature of Ebola requires that officials track down everyone who might potentially have been exposed. That’s the only way to keep it from flaring up again. It is not good enough, he said, to have just a little bit of Ebola.

“That’s like saying you’re only a little bit pregnant. This is Ebola. This is a horrible, unforgiving disease. You’ve got to get down to a level of zero,” Aylward said.

The latest WHO numbers show 8,914 suspected or confirmed cases of Ebola and 4,447 deaths. At a glance, such numbers might seem to suggest that half the people stricken with Ebola will survive the disease, but Aylward said that underestimates the true mortality rate, which is actually 70 percent. Many of the people who have Ebola, and are still fighting it, will yet succumb to the disease.

“We have had to carefully identify those individual patients for whom we could follow their entire course — when we do that carefully we find that 70% are dying and that this number is pretty robust across the 3 worst-affected countries,” Aylward wrote in an e-mail.

The trend in caseloads is “relatively flat,” with about 1,000 new cases a week for the past three or four weeks, he said. But the collection of data has been difficult in a region overwhelmed by the outbreak, and Aylward cautioned against drawing any conclusion from the numbers.

Phillip and Achenbach reported from Washington. Mark Berman, Brady Dennis and Lena Sun in Washington contributed to this report.