People who were on board the cruise ship hit with hantavirus will not be forced to stay in quarantine, Centers for Disease Control and Prevention officials said on May 13.

“There are no state or federal quarantine orders that have been drawn,” Dr. David Fitter, the CDC’s incident manager for hantavirus response, told reporters on a call.

A hantavirus outbreak was confirmed in early May on the MV Hondius, which set sail from Argentina on April 1. Nine cases have been confirmed, and three people have died.

The incubation for hantavirus, or time until symptoms manifest from infection, is believed to be up to 42 days.

At least some Americans who were on board and disembarked before the outbreak was confirmed flew home on commercial flights, CDC officials said.

California, Maryland, New York, and Washington state have said that residents were exposed to people who were on the ship, and that those people were being monitored at home for symptoms.

Fitter said that CDC officials are working closely with state and local officials, as well as with the passengers and their contacts, to convey appropriate information.

“We’re taking a conservative approach on this, and we really are encouraging people to stay at their home and work very closely with the state and local health departments to ensure that they are purposely monitored in that space,” he said.

Eighteen other Americans were flown from the MV Hondius earlier in the week to the University of Nebraska Medical Center or to a similar facility in Atlanta.

Fitter confirmed that those Americans will not be forced to remain at those facilities, but are being encouraged to stay there.

Those Americans include a doctor who tested positive for hantavirus, has experienced symptoms such as chills, and is in a biocontainment unit in Omaha, Nebraska. Authorities are waiting for the results of a new test. Another unidentified passenger who has shown hantavirus symptoms, and has since tested negative, is in a biocontainment unit in Atlanta.

Fifteen Americans who have not shown symptoms are in a quarantine area in Omaha, including Jake Rosmarin, who said that he plans to remain at the facility for the full incubation period.

It’s not clear whether any of those people have been tested. CDC officials said Wednesday that the CDC is recommending that people who were on the ship, or exposed to possible patients, get tested only if they are symptomatic.