Suspected transmission of norovirus in eight long-term care facilities attributed to staff working at multiple institutions.

This study reports on gastroenteritis outbreaks suspected of being norovirus infections in eight long-term care facilities. A descriptive epidemiological investigation was used to depict sources of infections and control measures. Outbreaks affected 299 (31%) of 954 residents and 95 (11%) of 843 staff. Attack rates were higher in residents (range 17-55%) than staff (range 3-35%). Person-to-person spread was suspected. The case-hospitalization rate was 2·5%, and no death occurred. Eight staff members were employed at multiple affected facilities and may have introduced disease into three facilities. Thirty-two stool specimens were positive for norovirus by real-time reverse transcriptase-polymerase chain reaction or enzyme immunoassay. Sequenced specimens were closely related to GII.4 New Orleans. A concurrent Clostridium difficile outbreak was also detected at one facility. Staff members who work at multiple facilities may transmit norovirus between them. Regulatory agencies should consider precluding ill staff from working in multiple facilities during outbreaks. Guidelines to control norovirus must be applied promptly and meticulously by facilities.