An outbreak of salmonellosis involving multiple vehicles.

A biphasic outbreaks of salmonellosis affected customers and employees of a restaurant in Maine, in October and November, 1979. Salmonella typhimurium was isolated from 27 customers and nine employees. Ten other individuals were ill but did not have specimens taken for culture, and there were four secondary cases including one affecting a laboratory technician. Fourteen individuals (28%) were hospitalized for up to 45 days, and a total of 416 days of work were lost as a result of the outbreak. Two different food items served at the restaurant at separate times were identified as vehicles. In the first part of the outbreak, 37 persons who consumed either egg-based foods (p = 0.003) or salad (p = 0.006) became ill. In the second phase of the outbreak, in late October and November, nine cases were associated with consumption of inadequately refrigerated salad (p = 0.008), but not with egg-based foods. An infected symptomatic food handler prepared the incriminated salad for some members of this latter group. Use of antacids was also associated with illness (p = 0.03). The occurrence of illness over a seven-week period, the implication of several vehicles, and the demonstration of secondary cases suggest that "sporadic" cases of salmonellosis in the community may be linked.