AbstractObjective:To determine risk factors for and modes of transmission of an outbreak of acute nonbacterial gastroenteritis among residents and staff in a nursing home.Design:Cohort study of residents and questionnaire survey of employees.Setting:One hundred twenty-bed nursing home in Alabama.Patients:From July 11,1991, through July 25,1991,77 of 120 residents (attack rate = 64%) and at least 14 of 49 employees (minimum attack rate = 29%) developed acute gastroenteritis characterized by vomiting and diarrhea; few residents developed fever > 100°F. Nine residents required intravenous rehydration, and 2 residents died.Results:The risk of developing illness was greater for female residents (64/92 versus 13/28; relative risk [RR] = 1.5; 95% confidence interval [CI95 ]=1.0-2.3) and for employees who reported handling residents' soiled linen, stools, or vomitus more frequently (>5 times a shift versus ≥ 5 times a shift: 7/13 versus 7/31; RR=2.4; CI95 = 1.1-5.4). Direct transmission of infection, probably via person-to-person spread, sustained the outbreak. Temporal clustering analysis demonstrated that the risk of becoming ill 1 or 2 days after a roommate became ill was significantly greater than that of becoming ill at other times during the outbreak (RR= 2.2; CI95 = 1.3-3.8). No Salmonella or Shigella species, ova, or parasites were identified from 12 fecal specimens obtained from ill residents.Conclusions:Although stool and serum specimens were not available for viral studies, the clinical symptoms and incubation period were consistent with illness due to Norwalk-like viral agents. This outbreak emphasizes the severity of acute nonbacterial gastroenteritis among elderly and debilitated residents of nursing homes and the need for prompt use of enteric precautions in controlling outbreaks of gastroenteritis in these facilities.
