Children’s Hospital of Philadelphia recently improved its virus-detection process after a state Health Department investigation revealed the room of a patient suffering from norovirus in April was inadequately cleaned amid an outbreak among nurses there.

The Health Department report was based on an investigation completed in May after 19 nursing staffers working in the same unit fell ill with norovirus – a highly contagious but generally nonlife-threatening gastrointestinal bug that causes vomiting and diarrhea.

The report found that the room of a patient suffering from the virus in the same unit on the weekend of April 5-6 had not been properly cleaned with bleach as required by the hospital’s infection-control policy. All but three of the affected staffers had developed symptoms between March 11 and March 23, before the inadequate cleaning, according to the report.

The report said hospital procedures also were not properly followed in early March when a patient’s mother displayed norovirus symptoms March 8 while visiting. “There was no documented evidence that [Infection Control] was notified of this incident,” the report said. Whether that patient room was adequately cleaned is unclear in the report.

The Health Department investigation also found that staffers who were out sick with norovirus were not instructed to follow hospital protocol of staying home until they were symptom-free for 48 hours until March 27 – after the majority of the affected staff already had been ill. Only three additional staffers fell ill after that date, the report said.