Last Updated Oct 6, 2014 1:42 PM EDT
OMAHA, Neb. -- An American photojournalist who contracted Ebola while working in Liberia arrived Monday in Nebraska, where he will be treated for the virus that has ravaged West Africa.
Ashoka Mukpo, 33, is the second Ebola patient to be treated at the Nebraska Medical Center's specialized isolation unit. Mukpo was working in Liberia as a freelance cameraman for NBC News when he became ill last week.
Mukpo is the fifth American to return to the United States for treatment since the start of the latest Ebola outbreak, which the World Health Organization estimates has killed more than 3,400 people.
"He's enormously relieved to be here, of course," Diana Mukpo said of her son, whom she was able to speak with through a video chat. "It's still quite frightening, but he's hanging in, and he sounds very strong."
"He's strong and his symptoms are not more advanced then when he talked to us before he left which is a relief," said Dr. Mitchell Levy, Mukpo's father.
His parents said Mukpo wasn't sure how he contracted Ebola, but believed it may have happened when he was helping to decontaminate a vehicle in which an Ebola patient had died.
Mukpo's parents said they tried to convince their son, who spent two years in Liberia working with a nonprofit, not to return there last month.
"I told him he was crazy," Levy said. "Our son is strong-willed and determined. He has always lived by his integrity. He made a strong connection with the Liberian people and felt compelled to go back. I told him I thought he was crazy and I told him about the risks but none of it worked. I'm proud of him but I wished he would go somewhere safer."
"And I begged him from a mother's perspective, I said 'Please don't go,'" Diana Mukpo said.
The Nebraska hospital's biocontainment unit was created in 2005 specifically to handle this kind of illness, said Dr. Phil Smith, who oversees the unit. Doctors at the isolation unit -- the largest of four nationwide -- will evaluate Mukpo before determining how to treat him.
"With any disease, everybody doesn't have the exact same symptoms and they don't have the exact same progression," said Dr. Ali Khan, dean of the University of Nebraska Medical Center college of public health.
Doctors said they would apply the lessons learned while treating American aid worker Rick Sacra in September. Sacra was successfully treated in the Nebraska unit and was allowed to return to his home in Massachusetts after three weeks, on Sept. 25.
After Sacra was released, the Nebraska Medical Center set up a separate lab within the isolation unit, so test results would be available more quickly and samples wouldn't have to be sent across campus to the main lab.
Doctors in Omaha said they were in constant communication with health centers where other Ebola patients are being treated, both in the U.S. and around the world.
Sacra, 51, was put under observation on Saturday after he came to a Boston-area emergency room with complaints of a persistent cough and other fatigue.
Doctors at UMass Memorial Medical Center said tests showed that Sacra does not have the Ebola virus again. He was released from the hospital Monday afternoon.
While in Nebraska, Sacra received an experimental Tekmira Pharmaceuticals drug called TKM-Ebola, as well as two blood transfusions from another American aid worker who had recovered from Ebola at an Atlanta hospital. The transfusions are believed to help a patient fight off the virus because the survivor's blood carries antibodies for the disease. Sacra also received supportive care, including IV fluids and aggressive electrolyte management.
But doctors have said they can't be sure what helped Sacra recover because he was receiving multiple treatments.
Meanwhile in Texas, Gov. Rick Perry said he would create a state task force to ensure Texas responds to infectious diseases like the Ebola virus.
The Task Force on Infectious Disease Preparedness and Response will be overseen by Dr. Brett Giroir, the CEO of Texas A&M Health Science Center. It will develop rapid-response plans if an outbreak is confirmed in the state.
Perry also called on federal officials to implement screening procedures at all U.S. points of entry. Screeners would take travelers' temperature and conduct other assessments to determine their overall health.
In Dallas, another man who recently traveled to the U.S. from Liberia was listed in critical condition Sunday. Thomas Eric Duncan has been hospitalized at Texas Health Presbyterian Hospital since Sept. 28. Dr. Tom Frieden, director of the federal Centers for Disease Control and Prevention, said he was aware that Duncan's health had "taken a turn for the worse," but he declined to describe Duncan's condition further.
The virus that causes Ebola is not airborne and can only be spread through direct contact with the bodily fluids - blood, sweat, vomit, feces, urine, saliva or semen - of an infected person who is showing symptoms.
Duncan arrived in Dallas on Sept. 20 and fell ill a few days later. Officials say 10 people definitely had close contact with Duncan and a further 38 may have been around him when he was showing symptoms of the disease.
Before he was admitted to the hospital, Duncan stayed with Louise Troh, her 13-year-old son and two nephews in their northeast Dallas apartment. The family has been kept in isolation in an undisclosed location since Friday and a hazardous materials crew has decontaminated their home twice. No one in the family has developed Ebola symptoms.
On Sunday, Troh told The Associated Press that she was afraid the crew might damage or destroy some irreplaceable keepsakes that she was forced to leave at the apartment, including photographs and recordings of her daughter, a singer, who died in childbirth.
"If they throw out her picture, her recordings, I'll be hurt. Her live CD's in there. That's all I have to show her children in the future. I don't want to miss it," she said in a phone interview.