Outbreaks of gastroenteritis due to Norwalk-like virus in two long-term care facilities for the elderly

In February 1993, outbreaks of gastroenteritis due to Norwalk-like viruses occurred simultaneously among the elderly residents of two long-term care facilities. Facility A instituted infection control measures that included increased surveillance, reinforcement of handwashing, keeping symptomatic residents in their rooms and relieving symptomatic staff of their work duties until 48 h after resolution of their symptoms. Facility B instituted a more stringent set of control measures that included all those implemented by facility A plus the following: staff from affected units were not permitted to work on other units, affected units were closed to new admissions, enteric precautions were instituted for ill residents, residents were restricted to their own units and education was provided to staff and residents about gastroenteritis. Facility A had an attack rate of 9%; the attack rate for facility B was 11% (P = 0.38). The duration of the outbreak was 29 days in facility A and 24 days in facility B. The impact these infection control measures had on the course of the outbreaks is difficult to determine. However, it is doubtful that the more stringent measures implemented at facility B had any greater effect on the course of the outbreak. A better understanding of the precise mechanisms of viral transmission is required in order to determine the most appropriate control measures for gastroenteritis due to Norwalk-like viruses in long term care facilities.