A persistent outbreak of norovirus at a Nebraska event center that may have sickened 159 people was linked to ineffective prevention efforts, according to a CDC report.

The Nebraska Department of Health and Human Services learned of a suspected outbreak of 33 cases of norovirus among attendees of a wedding reception in October of 2017. Investigators found that a total of 6 employees and 153 individuals, including 120 who attended subsequent events at the facility, developed symptoms consistent with norovirus over several weeks. Three of the cases were confirmed by testing. Many of the cases occurred after facility management was instructed by investigators to use Environmental Protection Agency–registered disinfectants and exclude employees who might be ill from work for at least 48 hours after symptom resolution. “However, [the facility] performed minimal environmental cleaning and did not exclude ill employees,” the authors wrote.

The virus is known to persist on environmental surfaces for up to 2 weeks, resists most commercial disinfectants, and as few as 18 virus particles are enough to cause an infection, the authors note. Investigators discovered that at the initial reception, a person vomited on the carpet in the lobby, but the carpet was not adequately sanitized, which may have led to contamination of other surfaces. Additionally, at least 1 employee involved in food handling returned to work prior to the recommended 48 hours despite investigators’ recommendations after the initial cases were reported.