Gastroenteritis outbreak in a Maryland nursing home

From December 25, 1990, to January 12, 1991, an outbreak of acute viral gastroenteritis occurred among 132 residents and 102 employees of a Maryland nursing home. Illness typically lasted 24 hours and was characterized by diarrhea, vomiting, and fever. The attack rate was 46.2% (61/132) for residents and 42.2% (43/102) for employees. No differences in attack rates were observed by station in the facility. The risk of having an early case (before the peak of the outbreak on January 2, 1991) was 3.5 times greater for employees with patient contact than for employees without patient contact. Analyses of temporal and geographic clustering of cases suggest that person-to-person transmission was an important transmission mode. Although an etiologic agent was not identified, the short duration of illness, high rates of vomiting and diarrhea, and high attack rate are consistent with Norwalk-like viral infection.