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Epidemiologic Notes and Reports Shigellosis in Day-Care Centers -- Washington, 1983

In late September 1983, two clusters of Shigella sonnei infection associated with high rates of diarrheal illness occurred among children and staff in two Seattle, Washington, day-care centers. No link was discovered between the two centers, and the antimicrobial resistance patterns associated with the isolates from the two centers differed. Circumstances dictated that the smaller center be closed. The larger one remained open, and in a departure from a previous strict exclusionary policy, convalescent children and staff under antimicrobial treatment were encouraged to return to the center, where they used a separate room, bathroom, and playground until they had two consecutive negative cultures off treatment. The parallel occurence of these two outbreaks at a time of low Shigella activity in the community permitted the measurement of the efficacy of the control strategies, using community surveillance.

Diarrheal illness attack rates were similar at the two centers from September 5 to October 17 among the children (23/80 and 11/23), staff (6/12 and 3/3), and family members of ill children (14/35 and 9/21) surveyed at the centers. Eighty-three other day-care centers surveyed in the same or adjacent ZIP-code areas as the affected centers showed a background diarrheal illness prevalence rate during September of 47/1313 (3.6%) of attending children, and 12/261 (4.6%) of staff.

The two different intervention strategies produced differences in the requirements for alternate care at the two day-care centers. The first day-care center was closed for 24 working days, during which alternate care arrangements had to be made for the 23 children who had attended it. At the second day-care center, alternate care arrangements were necessary for the duration of diarrhea only for the estimated nine children who were ill at the time the isolation room was created. A single case of culture-negative diarrheal illness occurred among the children at each of the centers in the 2 weeks following public-health intervention; no shigellosis was documented among the children at either center in the next 2 months.

From September 1 to December 31, 11 S. sonnei isolates were reported to the Seattle-King County Department of Public Health, which were not epidemiologically linked to either center. Plasmid analysis of these isolates is pending. Public-health management of these two simultaneous outbreaks may have limited the further spread of illness within both centers. The strategy of bringing convalescent children under treatment back into the center before they had negative cultures was not associated with further spread of Shigella in that center. Reported by K Johnson, MPH, J Boase, MS, SD Helgerson, MD, Seattle-King County Dept of Public Health, JM Kobayashi, MD, State Epidemiologist, Washington State Dept of Social & Health Svcs; Enteric Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: It has been estimated that 11,000,000 children in the United States are in full- or part-time day care (1). The growing need for day care has brought a growing need for controlling infectious diseases that frequently affect children in day care. First reported to CDC in 1972, shigellosis in day-care centers has become a common and often frustrating problem. Day-care centers play an important role in the transmission of shigellosis in the community (2,3). Difficulties in controlling this infection in the day-care setting include the low infectious dose, the unpredictable acquisition of antimicrobial resistance, the frequency of mild and inapparent infections, and the frequency with which young children are transferred from one day-care center to another. Although a rigorous handwashing policy has been shown to reduce the incidence of nonspecific diarrheal illness in day-care centers, satisfactory control measures for shigellosis have not been documented (4). On one occasion, the policy of rigid exclusion of convalescent children until they became culture-negative was associated with spread of the infection to an adjacent county (5).

The Seattle outbreak suggests that shigellosis in day-care centers may be a controllable problem under certain circumstances. Control strategies incorporating the early return of convalescent children to isolation settings in the day-care center are worthy of further evaluation. Further evaluation of surveillance and control strategies is necessary before general recommendations can be made. A symposium entitled, "Infectious Diseases in Day Care: Management and Prevention," will be held in Minneapolis, Minnesota, June 21-23, 1984. For further information, contact Donna Dacus, Department of Conferences, University of Minnesota; telephone (612) 376-2578.


  1. Abt Associates. Children at the center: summary findings and policy implications of the national day care study. Cambridge, Massachusetts: Abt Associates, Inc., 1979;I.

  2. Weissman JB, Schmerler A, Weiler P, et al. The role of preschool children and day-care centers in the spread of shigellosis in urban communities. J Pediatr 1974;84:797-802.

  3. Weissman JB, Gangarosa EJ, Schmerler A, et al. Shigellosis in day-care centres. Lancet 1975;I:88-90.

  4. Black RE, Dykes AC, Anderson KE, et al. Handwashing to prevent diarrhea in day-care centers. Am J Epidemiol 1981;113:445-51.

  5. Tacket CO, Cohen ML. Shigellosis in day care centers: use of plasmid analysis to assess control measures. Pediatr Infect Dis 1983;2:127-30.

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