A healthcare worker infected with the deadly Ebola virus currently in serious condition has arrived in the United States from Sierra Leone for treatment at a Maryland hospital run by the National Institutes of Health on Friday.

According to Maggie Fox and Alexander Smith of NBC News, the unidentified patient, the 11th Ebola case treated in the U.S., was flown back to the country from West Africa in isolation on a charter flight. The NIH issued a statement about how it will treat the patient.

"The unit staff is trained in strict infection control practices optimized to prevent spread of potentially transmissible agents such as Ebola. In addition, access to the unit is strictly controlled," the federal health agency said. "NIH is taking every precaution to ensure the safety of our patients, NIH staff, and the public."

According to the NIH, the patient worked as a volunteer in an Ebola treatment unit in Sierra Leone. The health agency noted that it was the second patient with the Ebola virus they treated at the NIH Clinical Center.

"The NIH admitted the patient to its high-level containment facility in Bethesda, Md.," Fox and Smith wrote. "It's the same unit that treated nurse Nina Pham and that kept watch over a doctor and a nurse who were eventually found to have escaped infection."

The Centers for Disease Control and Prevention told NBC News that an American who had close contact with the patient would be placed into isolation in Atlanta.

"The individual has not shown symptoms of Ebola and has not been diagnosed with Ebola," the CDC said. "Upon arrival in Atlanta, the individual will voluntarily self-isolate and be under direct active monitoring for the 21-day incubation period."

NBC News reported that the CDC is trying to track down anyone in West Africa who might have been in contact with the patient, including several Americans. The agency also sent down some staff members to help fight Ebola.

"At this time, none of these individuals have tested positive for Ebola," CDC said in a statement.

However, the CDC indicated that "contingency plans" have been developed with the State Department "out of an abundance of caution" to return Americans potentially exposed to the virus back to the U.S. "by non-commercial air transport."

"These individuals are volunteers in the Ebola response and are currently being monitored in Sierra Leone," the CDC said. "Those individuals will voluntarily self-isolate and be under direct active monitoring for the 21-day incubation period."

NBC News cited a statistic from the World Health Organization that more than 24,000 people in West Africa have been infected with Ebola, and 10,000 died as a result. In the United States, 10 people were treated for the deadly virus, but only two have died from the infection.