An American health worker who was possibly exposed to Ebola while treating patients in Congo was evacuated to the United States on Saturday and placed in a secure area at the University of Nebraska Medical Center, hospital officials said. The person has no symptoms of the deadly hemorrhagic fever and is not contagious, but will be monitored closely for up to two weeks, hospital officials said.

If symptoms develop and the person tests positive for the disease, the individual will be admitted to the medical center’s biocontainment unit. The person was treating patients outside the urban epicenter of the outbreak and had contact with a patient who was later diagnosed with Ebola, according to U.S. officials.

“We are not aware of any other United States citizens with potential exposures to Ebola at this time, and there is no health risk to the U.S. public due to this evacuation,” according to a statement from the Centers for Disease Control and Prevention. The individual was flown back to the United States in a private plane, not commercial aircraft.

The individual will be monitored in a unit at the medical center that can safely quarantine individuals exposed to highly infectious diseases, such as Ebola.

“CDC recognizes that Ebola generates a lot of public worry and concern,” the statement said, noting that the agency has “several measures available” to prevent the introduction of disease in the United States. Ebola patients or people who have been exposed to Ebola can be safely transported to the United States and cared for when appropriate precautions are used and infection control procedures are in place to prevent transmission to others, the CDC said.

The American was among hundreds of health-care personnel who have been responding to a growing Ebola outbreak in Congo, the second largest in history, with nearly 600 cases and 360 deaths. The outbreak in northeastern Congo has been especially difficult to control because it is taking place in an active war zone. Attacks on government outposts and civilians by dozens of armed militias have complicated the work of Ebola response teams, who often have had to suspend crucial work tracking cases and isolating people infected with the deadly virus. Violence has escalated in recent weeks near Beni, the urban epicenter in North Kivu province, and the city of Butembo.

Congo’s health ministry, the World Health Organization and some nongovernmental organizations have had their Ebola containment work disrupted because of protests related to Sunday’s presidential election. The government issued a last-minute decision to bar people in Beni and Butembo from voting because of the outbreak. About a dozen U.S. government personnel, including Ebola experts from the Centers for Disease Control and Prevention, are working on the Ebola response in the Congolese capital of Kinshasa, about 1,000 miles away.

Taylor Wilson, a spokesman for the University of Nebraska Medical Center, said the potential exposure took place about a week ago. After the exposure, the health worker received the experimental Ebola vaccine that has been given to more than 53,000 people in Congo, including health-care personnel, according to U.S. officials.

“This person may have been exposed to the virus but is not ill and is not contagious,” said Ted Cieslak, an infectious diseases specialist with Nebraska Medicine and associate professor of epidemiology in the University of Nebraska Medical Center College of Public Health.

The Ebola virus cannot spread to others when a person shows no signs or symptoms of the disease. Symptoms include fever, severe headache, diarrhea, and unexplained bleeding or bruising. Symptoms may appear anywhere from 2 to 21 days after contact with the virus, with an average of 8 to 10 days.

If the exposed person develops symptoms, Cieslak said, the Nebraska team is among the most qualified in the world to deal with them because of the medical center’s previous experience caring for Ebola patients. The individual will be monitored in a secure area inaccessible to the public and patients. Monitoring could last up to two weeks, hospital officials said.

The virus spreads through direct contact with blood or body fluids of a person who is sick with or has died of the disease or through semen from a man who has recovered from the disease. It can also spread through objects contaminated with body fluids from a sick or dead person.

While this exposed individual isn’t officially a patient, hospital officials said they will be honoring the person’s request for privacy. The hospital also said it will not be providing updates on the person’s status unless the person needs to be transferred to the special biocontainment unit.

Nebraska Medicine treated three patients with Ebola during the epidemic that ravaged Liberia, Sierra Leone and Guinea from 2014 to 2016. In 2015, several others were monitored after exposures, none of whom developed the disease. Nebraska Medical Center is one of a handful of places in the United States that has a dedicated biocontainment unit.

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