One American from the MV Hondius cruise ship has tested positive for the hantavirus and is being watched closely in a special medical facility in Nebraska, while another has shown symptoms of the illness and is in a biocontainment unit in Georgia, officials said on May 11.

Neither person from the ship, on which an outbreak of the virus occurred, has been identified.

Sixteen other Americans are in quarantine in Omaha or Atlanta.

Here’s what to know.

3 Isolated in Biocontainment Rooms

The person who tested positive on a polymerase chain reaction test for hantavirus is being monitored in a biocontainment unit at the University of Nebraska Medical Center, officials said at a news briefing in Omaha on May 11.

The test was on a specimen collected outside the United States, as was another test that came back negative, according to Dr. Brendan Jackson, acting director of the Centers for Disease Control and Prevention’s Division of High-Consequence Pathogens and Pathology.

The individual is not showing symptoms but is being monitored closely, Dr. Angela Hewlett, medical director of the biocontainment unit, told reporters. People who were exposed to the hantavirus but show no symptoms are not automatically tested, but this person will be tested at least once more in the coming days because he or she tested positive recently, she said.

Doctors likened the biocontainment unit to a well-equipped intensive care room with specially-designed air and waste systems. There are five rooms inside the unit, one of which is currently being used as a laboratory to quickly process any necessary tests.

Six cases have been confirmed, and two others are suspected, the World Health Organization said over the weekend. Two of the confirmed patients and one of the suspected patients have died.

The global organization said a ninth suspected case has been reclassified because that person tested negative.

The American was one of numerous people evacuated to their home countries from the Canary Islands, where the ship sailed after departing from Argentina and stopping in Antarctica and other places.

Another American who was on the cruise ship and showed symptoms, along with someone who is in a relationship with that person, were transported to a biocontainment unit at Emory University in Atlanta.

Both the University of Nebraska and Emory University are part of a nationwide system set up to handle people who have been infected with or exposed to serious pathogens.

15 in Quarantine Facility

Fifteen additional Americans are in a separate area on the University of Nebraska campus called the quarantine unit, which does not have unique medical capabilities but is able to comfortably accommodate people who have shown no symptoms and have not tested positive.

Those people are being monitored for symptoms and may be tested. A primary benefit of being in the unit is that any individuals who do test positive or develop symptoms can be quickly moved to the biocontainment unit, university officials said. Hantavirus has no approved treatments. Doctors “rely on aggressive supportive care,” such as intravenous fluids and mechanical intubation, Hewlett said.

“We do think that being able to provide those aggressive measures to people can change outcomes, and that’s the importance of being close to this type of care, and to be able to provide that critical care for individuals, should they need it,” she said.

The people range in age from late 20s to late 70s or early 80s, officials said.

U.S. authorities said over the weekend that 17 Americans were being flown to the United States. They added a British American dual national to the count on May 11.

“All individuals in both facilities will receive clinical assessment and appropriate care and support based on their condition and needs,” the Department of Health and Human Services said in a statement on X.

An unspecified number of other Americans who previously left the ship have returned home, none of whom have developed symptoms or tested positive for the hantavirus.

State officials are aware of these Americans and have made sure they know to alert officials if they develop symptoms, authorities said on May 11. Symptoms can include cough, vomiting, and shortness of breath.

Risk Low, but No Guarantees

Dr. Brian Christine, assistant secretary for health and head of the U.S. Public Health Service, said at the briefing that the risk to the public from hantavirus is “very, very low.”

The strain that spread on the MV Hondius has been identified as the Andes variant.

The Centers for Disease Control and Prevention said in a health alert on May 8 that “the risk to the public’s health in the United States is considered extremely low at this time.”

Although the Andes variant can spread from person to person, that usually happens only after prolonged close contact or contact with bodily fluids such as saliva from an infected person, the agency said.

Jackson declined to say that no Americans will contract the virus.

“There are no guarantees in life,” he said. “We’re putting as many measures in place as possible to ensure that people are safe and healthy and we keep the communities safe and healthy as well.”

Health Secretary Robert F. Kennedy Jr. told reporters in Washington on May 11, “We have this under control, and we’re not worried about it.”

Dr. Jay Bhattacharya, the acting director of the Centers for Disease Control and Prevention, said on CNN on May 10 that this is not COVID-19 and that officials “don’t want to treat it like COVID” or “cause a public panic.” He said that protocols that were successful in containing hantavirus outbreaks in the past are being followed, including monitoring people who were exposed for symptoms, and that the hantavirus does not spread from asymptomatic people.

Will Be Held for Some Time

The Americans being housed at the facilities in Nebraska and Georgia will be there for some time, officials said.

“They’re going to be here for at least a few days,” Jackson said.

Doctors carried out initial assessments after the passengers were flown in on the morning of May 11.

After allowing the people to rest, further assessments were planned.

If the people remain symptom-free and they have conditions at home that would allow them to isolate through the end of the possible incubation period of 42 days, then they may be free to go home, Jackson said.

“There’s a range of structures that need to be in place before anyone would be transferred to their home, and that would be done in close coordination with the health department in the states that would be receiving them,” he said.

He said that ultimately, it would be up to the individuals.

The people will also have the option to remain in the facilities for the entire incubation period if they choose.