Federal health officials rushed Friday to assure a frightened public that Ebola does not pose a serious threat in the U.S., even as the first — and thus far only — diagnosis on American soil exposed potential flaws in border screening, treatment and disposal of contaminated items.

As Ebola patient Thomas Eric Duncan, who showed symptoms of the often-fatal disease shortly after arriving from Liberia, was in serious condition and being treated in isolation at Texas Health Presbyterian Hospital, relatives in Dallas resisted a quarantine amid reports that cleanup specialists were balking at disinfecting their home. 

Still, Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention (CDC), insists he's confident Ebola can be contained in the U.S., unlike in Africa where it has killed more than 3,300 since the current outbreak began late last year.

“I have no doubt we will control this case of Ebola so that it does not spread widely,” Frieden said.

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So far, Duncan's diagnosis is the only verified one in the U.S. A man who was isolated in a Hawaii hospital after showing symptoms consistent with Ebola has been cleared, although on Friday, a spokeswoman for Howard University in Washington said the university's hospital has admiteed a patient who had been in Nigeria and showed possible symptoms.

Frieden's assurances came amid calls for better screening of U.S.-bound passengers from Ebola-affected nations and word that Duncan's initial triage was bungled at the hospital.

At a Dallas apartment where Duncan stayed after arriving Sept. 20, family members were legally quarantined Thursday after refusing to comply with Dallas health officials requests that they stay home. Doctors are taking the temperatures of four family members in the unit where Duncan was staying twice a day to monitor symptoms as part of the health surveillance efforts being led by CDC officials and local Dallas authorities.

Texas health officials told reporters during a press conference Thursday that the family would be quarantined in their apartment unit for the next 20 days until the potential incubation period for Ebola is over. 

On Thursday, a Springfield, Mo., microbiologist and emergency trauma physician who runs a charity in Guatemala, appeared at Atlanta’s Hartsfield-Jackson International Airport dressed in protective gear to protest what he called mismanagement of the crisis by the federal Centers for Disease Control and Prevention.

“If they’re not lying, they are grossly incompetent,” said Dr. Gil Mobley, who cleared airport security wearing a mask, goggles, gloves, boots and a hooded white jumpsuit emblazoned on the back with the words, “CDC is lying!”

In Duncan's homeland, authorities vowed to prosecute him for allegedly lying on an airport screening form by answering “no” to questions about whether he had “cared for an Ebola patient or touched the body of someone who had died in an area affected by Ebola." In truth, Duncan reportedly had helped carry a 19-year-old pregnant woman to a taxi to go to the hospital just five days before he boarded a U.S.-bound flight. The woman later died.

“There were no signs of any disease when the gentleman boarded the flight,” said Dr. Tom Kenyon, director of the CDC’s Center for Global Health. “This was not a failure of the screening process at the airport.”

But the ease at which Duncan passed the screening, coupled with the fact that Ebola victims may not become symptomatic for weeks after exposure, raised questions about how best to keep the disease off American soil. Jessica Vaughn, a researcher affiliated with the nonprofit Center for Immigration Studies in Washington, said officials have the right to ban anyone from entering the U.S. if they pose a potential threat to public health or safety. 

“Other countries are banning travellers from outbreak countries, and we should, too,” Vaughn told The Washington Post. “In the middle of a health crisis, the government should be setting up more robust screening protocols.”

Meanwhile, health officials in Dallas acknowledged that Duncan’s clothing and bedding were still in plastic bags and had not been removed, The Dallas Morning News reports. Officials were seemingly unsure how to delegate the removal of contaminated items from the apartment. 

Asked why Duncan's items and clothing were still at the location, the county's Health and Human Services director responded that it wasn't his agency's responsibility.

The items will soon be "appropriately disposed of," a county judge said.

Health officials widened their search Thursday to 100 individuals possibly exposed to the disease — tracing contacts of the patient and medical staff who initially treated him. Also on Thursday, officials said three more young children potentially had contact with Duncan, bringing the number of kids being monitored to eight.

“We’re going to break that risk down to high-risk, no-risk and low-risk, and that’s going to be the basis of our contact tracing,” said David Daigle, associate director for communications, public health preparedness and response at the CDC.

Daigle expressed concern about infection control at Texas Health Presbyterian Hospital, where Duncan is currently in isolation, and said that a team was dispatched to conduct the same kind of contact tracing officials are doing in the local community.

Zachary Thompson, director of Dallas County Health and Human Services, tried to quell fears in the community of the virus spreading and stressed transparency during the investigation.

“A lot of the individuals that we come in contact with will not have any symptoms, they will not have any association other than the fact that someone said they were there, or they might have had contact,” Thompson said. “This is local public health surveillance at its best, in what we do day in and day out.”

Police were stationed at the Ivy Apartment complex where the family lives Thursday to keep the peace and assist residents and health officials in the community during the investigation.

“We want to make sure we create a calm and safe environment for [health officials] to do their work — that’s our primary focus.  We have had reverse 911 calls to all the residents … We’ve talked to them, we’ve explained what happened, and we’ve given them the option to call us back,” said Dallas city mayor, Mike Rawlings. ”If citizens have any questions, they need to call 311. We will be able to give them a full explanation of what’s happening and answer any questions that are challenging.”

Additional nurses and health professionals were called into schools where the five students that were potentially exposed to Ebola attended.

“Our nurses are making two rounds every school day to every classroom just to check to see if anyone has questions or if there are any symptoms,” said  Mike Miles, superintendent of Dallas Independent School District, adding that additional custodial staff was on hand to clean and disinfect the buildings the students attended. Miles stressed the fact that the potential for contamination in the schools was minimal, but said they were doing extra cleaning to take the possibility off the table.

The eight students in the potential contacts were enrolled in a homebound program where they will receive curricular and technology support to complete their coursework while they are out of school. Attendance at the five schools involved in the investigation was down 10 percent Thursday, but Miles said he expects it to go back up.

Sally Nuran, manager of the Ivy Apartments where Duncan was visiting family, said during a press conference Thursday that health officials alerted her of the Ebola case on her property late Monday night. She confirmed that the lease for that particular unit lists one adult and two children, but said she does not know how many people are currently occupying the space.

As part of the monitoring process, the CDC has quarantined the family inside the unit, with strict instructions not to leave the apartment or even step out on the porch, according to Nuran. The family was set to move out of the apartment when their lease expired on September 30.

The complex is home to residents of many different nationalities and translators have been on hand to distribute information in at least eight different languages, according to Nuran, who said she’s working with the CDC and other government agencies to educate residents about the current situation.

Fliers were placed on residents’ doors in the apartment complex Wednesday night and more translated fliers will be handed out during a community meeting Thursday, according to Nuran, who said language barriers have made it difficult to disseminate information. All common areas have been disinfected by the CDC, she said.

FoxNews.com's Jessica Mulvihill and The Associated Press contributed to this report.