A dozen workers at the university medical center in Nijmegen will enter a precautionary quarantine after possible exposure to hantavirus. The 12 employees at the Radboudumc hospital were involved in the case of a patient who tested positive for the viral infection after spending time on the Hondius cruise ship, the hospital said in a statement.

The workers at the hospital did not follow a specific, strict protocol when handling the infected patient’s blood and urine. Despite the risk of infection being low, the workers will remain in “preventive quarantine for six weeks as a precaution,” the hospital wrote on Monday. It has not been revealed whether the people at risk are nurses, orderlies, doctors, medical students, or if they hold other positions.

Three people died from hantavirus after a recent outbreak involving the 147 passengers and crew members on the Dutch-flagged vessel. Two of the fatal victims were identified as a man and woman from Friesland, while the third was reported to be a German woman. So far, at least seven have tested positive for the viral infection, with several others suspected of carrying the infection.

One of those infected has been in treatment at the hospital since Wednesday. Blood was drawn from the patient and processed using standard safety precautions. “Due to the nature of the virus, this blood should have been processed according to a stricter procedure,” the hospital stated in the update on Monday.

“In addition, it became clear on Saturday, May 9, that the most up-to-date international regulations had not been followed during the disposal of the patient’s urine.” The staff members will receive any support needed.

At the time the patient was admitted, Radboudumc stated, “On the ward where the patient is admitted, appropriate isolation measures have been taken to prevent spread, in accordance with internationally agreed protocols. The team is specialized and trained in the care of patients with severe infectious diseases.”

“Despite the fact that the chance of actual infection is very small, these measures have a significant impact on all those involved. We regret that this has happened at our university medical center. We will carefully investigate the course of events to learn from this and to prevent it from happening in the future,” said Radboudumc Executive Board Chair Bertine Lahuis.

The patient at Radboudumc was one of three taken as part of a medical evacuation from Cape Verde to the Netherlands last week. The second was transported to a hospital in Germany and tested negative for the hantavirus, while the third was admitted to the Leiden University Medical Center.

The last of the passengers remaining on the Dutch-flagged ship were able to exit the vessel on Monday after weeks of uncertainty.