Having employees stay at home when sick with norovirus helps prevent norovirus outbreaks in nursing homes, U.S. health officials said.

The Centers for Disease Control and Prevention's Mortality and Morbidity Weekly Report summarizes an in-depth epidemiologic investigation of three norovirus outbreaks that occurred in a long-term residential treatment facility in Oregon in 2007.

Each of the three outbreaks was caused by a different norovirus strain. Risk factors for norovirus infection among facility employees and multiple infection control barriers and lapses were identified.

The findings highlight the importance of timely implementation of standard infection control practices and targeted norovirus control measures as recommended by both the Centers for Disease Control and Prevention and the Oregon Public Health Division to prevent and control norovirus outbreaks in large residential treatment facilities.

Noroviruses are a group of related viruses that cause acute gastroenteritis in humans that are transmitted primarily through the fecal-oral route, either by consumption of fecally contaminated food or water or by direct person-to-person spread.