Health officials are monitoring four California residents exposed to the Andes hantavirus outbreak related to the MV Hondius Dutch cruise ship, the state’s public health department reported May 11.

Two of the residents have returned home and are being monitored by local health officials and two have been transported to Nebraska by federal authorities.

The two in Nebraska will return to California after their health assessments have been completed and arrangements have been made to protect their and the public’s health, the California Department of Public Health (CDPH) said in a statement.

Three residents were aboard the cruise ship during the outbreak, and the fourth resident was on an international flight sitting near a cruise passenger who was later confirmed to have Andes hantavirus, CDPH reported.

The risk to the public remains extremely low, the department stated.

“We understand public concern about this unusual outbreak,” said State Public Health Officer and CDPH Director Erica Pan. “Decades of experience in South America have shown that this Andes hantavirus rarely spreads between people.”

The department is continuing to work with federal and local officials to monitor the health of those exposed and prepare for the others to return, she added.

Federal officials reported earlier in the day that one American from the cruise tested positive for the virus and was being watched in a biocontainment unit at the University of Nebraska Medical Center in Nebraska. That person was not showing symptoms of the illness and was being monitored closely, according to Dr. Angela Hewlett, medical director of the unit told reporters.

Another passenger had shown symptoms of the virus and was in a biocontainment unit in Georgia. Neither was identified by federal officials.

The Nebraska and Georgia facilities are part of a nationwide system set up to handle people infected or exposed to serious pathogens.

Sixteen other Americans were in quarantine in Omaha, Nebraska, or Atlanta. The quarantined group is being monitored for symptoms and may be tested.

On May 8, California health officials were notified that one California resident who was on the cruise had returned home.

Passengers wearing blue protective suits ride in a military bus after being evacuated from the Dutch, hantavirus-stricken cruise ship MV Hondius at the industrial port of Granadilla de Abona on the island of Tenerife in Spain’s Canary Islands on May 10, 2026. (Jorge Guerrero/AFP via Getty Images)

Public health contacted the returned passenger and began a protocol of taking daily temperature checks and assessments to check for any symptoms consistent with hantavirus. The person is also advised to modify activity, the department said.

After the Californians in Nebraska are returned home, local health officials will continue to monitor them, if necessary, and provide daily temperature and symptom checks.

California’s Viral and Rickettsial Disease Laboratory is one of the nation’s few public health laboratories with a validated diagnostic hantavirus PCR assay, which can test patients for the virus. The state also provides technical assistance to other labs across the country.