Under fire in the wake of Ebola cases involving two nurses, the Centers for Disease Control and Prevention issued updated Ebola guidelines Monday, focusing on better protecting health care workers.
"Even one health care worker infection is one too many," CDC Director Tom Frieden told reporters.
He stressed the importance of more training and supervision, and said that no skin should be exposed when workers are wearing personal protective equipment, or PPE.
"We're increasing the margin of safety with a real consensus guideline that has three key changes. One, training, practicing -- demonstrated hands-on experience so that the health care workers are comfortable donning and doffing PPE. Two, no skin exposure. Three, observation of every single step, putting on and taking off the PPE," Frieden said.
The changes come the same day the 21-day monitoring period ended for around four dozen people who had come into contact with Ebola patient Thomas Eric Duncan, who died from the virus. They are all now officially clear after not demonstrating any symptoms.
There are still other health care workers who treated Duncan who remain within the 21-day monitoring period, Frieden said.
While there are signs of hope in the United States and at least one more country in West Africa -- Nigeria was declared Ebola-free Monday, following an announcement that Senegal is rid of the virus -- Ebola is still spreading rapidly in Guinea, Liberia and Sierra Leone, health officials report.
More than 4,500 people have died from the virus in West Africa, according to the World Health Organization, which said the region is still suffering from "widespread and intense transmission" because patients don't have access to adequate health care. There's a social crisis, too. Orphans of victims are often abandoned, their relatives terrified of taking them in.
Here's the latest about the virus from around the world:
Texas officials' conflicting numbers
Dallas Mayor Mike Rawlings provided numbers that conflicted with information provided by Dallas County Judge Clay Jenkins. Jenkins told CNN that in addition to the 48 people whose quarantine ended Monday, there were 75 health workers being monitored.
Rawlings said 120 people were still being monitored. It was unclear how he came up with that total.
Among those in the clear is Duncan's fiancée, Louise Troh. Monday marks the 21st day since her last contact with Duncan, who was the first person to die of the disease in the United States.
"We are so happy this is coming to an end, and we are so grateful that none of us has shown any sign of illness," Troh said in a statement Sunday. "We have lost so much, but we have our lives and we have our faith in God, which always gives us hope."
Nurses fight back
Texas nurses Nina Pham and Amber Vinson, who helped care for Duncan, remain hospitalized as they battle the virus. Pham is in stable condition at a National Institutes of Health facility in Bethesda, Maryland, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. Vinson is at Emory University Hospital in Atlanta. Her family has not given permission to make her condition public.
"I want everyone to know that they are our heroes. In fact, all those who cared for Mr. Duncan and our colleagues are heroes," said Cole Edmonson, chief nursing officer at Texas Health Presbyterian Hospital in Dallas.
Nurses there held a press conference Monday to defend their hospital and their work.
"Our hospital is safe, and in my opinion we have the greatest group and team of nurses in the world," Edmonson said.
Ebola czar begins work this week
Ron Klain, the former chief of staff to two vice U.S. presidents who has been tapped as the Obama administration's "Ebola czar," will begin his new duties Wednesday, White House press secretary Josh Earnest said.
Klain is highly regarded at the White House as a good manager with excellent relationships both in the administration and on Capitol Hill. His supervision of the allocation of funds in the stimulus -- at the time an incredible and complicated government undertaking -- is respected in Washington. He does not have any extensive background in health care -- something many Republicans seized on -- but the job is regarded as a managerial challenge.
"He's strong. He's very tough," said CNN political analyst David Gergen. "It's important in this job to be a coordinator; you have to knock heads together. He's tough enough to do that."
A former chief of staff to Vice President Joe Biden and also to former Vice President Al Gore, Klain is president of Case Holdings and general counsel of Revolution, an investment group. He has clerked for the U.S. Supreme Court and headed up Gore's effort during the 2000 Florida recount.
CNN has learned that the Pentagon has designated four major military hospitals in the United States as treatment centers for any potential U.S. troops that contract Ebola while on deployment in West Africa.
For initial cases, troops would be evacuated to Walter Reed Army Medical Center in the Washington, D.C., area, according to a defense official.
If Walter Reed became overwhelmed with cases, the overflow would be sent to Womack Army Medical Center at Fort Bragg, North Carolina. After that, troops would be sent to Brooke Army Medical Center at Fort Sam Houston, Texas and then to Madigan Army Medical Center at Joint Base Lewis-McChord just outside Tacoma, Washington.
Nigeria: Ebola is gone
Nigeria was thrust in the Ebola spotlight in July after an infected air traveler introduced the virus to Lagos. The case spurred fears that the disease would spread across the city of 21 million and throughout Africa's most populous country.
In the end, Nigeria confirmed 19 Ebola cases, including eight deaths.
The World Health Organization said an aggressive government response and effective contact tracing helped keep the virus in check.
"This is a spectacular success story that shows that Ebola can be contained," WHO said Monday.
"Such a story can help the many other developing countries that are deeply worried by the prospect of an imported Ebola case," it said. "Many wealthy countries, with outstanding health systems, may have something to learn as well."
Nigerian health officials reached 100% of known contacts in Lagos and 99.8% at the second outbreak site in Port Harcourt, WHO said.
And unlike in Guinea, Liberia and Sierra Leone -- the combined epicenter of the outbreak -- all identified contacts in Nigeria were physically monitored every day for 21 days, the agency said.
The few who tried to escape the monitoring system were tracked down and returned to finish their required monitoring period.
For WHO to declare an Ebola outbreak over, a country must pass 42 days with active surveillance in place, supported by good diagnostic capacity, and with no new cases detected, the agency said.
The 42-day period is also twice the maximum incubation period for Ebola.
Doctors Without Borders: Worker has recovered
A worker with the international organization Doctors Without Borders announced Monday that a staffer in Norway who contracted Ebola in West Africa and was treated in Europe is now free of the virus.
He has been discharged from care, according to Doctors Without Borders' London office.
The organization is not releasing any more information, including the staffer's name or plans, citing patient confidentiality.
Elsewhere, in Atlanta, an Ebola patient treated at Emory University Hospital has been discharged. The patient has asked to remain anonymous, Emory said Monday, and left the hospital for an undisclosed location.
He is the third Ebola patient at Emory to recover and leave the hospital. The others patients were discharged in August. Emory said it is still treating a fourth patient, who arrived there last week.
Spain: Nurse's aide free of Ebola
Teresa Romero Ramos, who had contracted Ebola after caring for a patient with the deadly disease, is now free of the virus, Spain's Special Ebola Committee said Sunday.
A third test came back negative after two earlier tests showed the levels of Ebola in her system were almost nil. Romero has recovered enough to produce antibodies, virus expert Luis Enjuanes told CNN.
But she'll stay in the hospital for days, possibly a few weeks, to recover, Enjuanes said.
U.N. worker dies
An employee with the United Nations' entity for gender equality, U.N. Women, died over the weekend from Ebola, spokesman Stephane Dujarric said Monday. The staffer worked for the organization in Sierra Leone, and the worker's spouse is receiving treatment for the virus, according to Dujarric.