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Morbidity Surveillance Following the Midwest Flood -- Missouri, 1993

Heavy spring and summer rains during 1993 caused flooding by both the Mississippi and Missouri rivers and by streams in 84 of the 115 counties in Missouri; all 84 were declared federal disaster areas. The Mississippi River attained flood stage during July 15- August 2, and the Missouri River, during July 25-August 2; a total of 2,060,757 acres were submerged, and approximately 60,000 persons throughout Missouri were displaced (National Weather Service, unpublished data, 1993). At the request of the Missouri Department of Health, CDC provided assistance in implementing a surveillance system to monitor flood-related injuries and illnesses in the affected areas. This report presents preliminary findings of these surveillance efforts.

Routine public health surveillance in Missouri is based on active and passive surveillance systems for communicable, environmental, and occupational diseases. Because of public health concerns regarding the flood, additional surveillance systems were implemented during the impact and recovery phases of the flood and included 1) emergency shelter-based active surveillance to identify disease outbreaks or clusters of adverse health events (local communicable disease coordinators and other volunteers made daily phone calls to shelters to monitor flood-related injuries and illnesses and to obtain total daily census figures) and 2) hospital emergency department-based passive surveillance in 31 hospitals to identify flood-related injuries and illnesses.

The highest number of persons reported residing in shelters was 702 on July 28. The highest number of reported flood-related injuries and illnesses in shelters was 40 on July 26, when 510 persons resided in shelters. No acute disease outbreaks were identified by the active surveillance system during or after the flood.

Emergency departments used a standardized questionnaire to provide daily reports of visits for injuries and illnesses. During July 16-September 3, 524 flood-related conditions were reported through this system. Of these, 250 (47.7%) were injuries, 233 (44.5%) were illnesses, 39 (7.4%) were listed as "other," and two (0.4%) were listed as "unknown." A total of 234 patients were treated and released after initial presentation to a hospital emergency department; 32 were hospitalized. In 249 cases, the hospitals did not report the patients' final dispositions. Of the 250 reported injuries, the most common were sprains/strains (86 {34%}), lacerations (61 {24%}), "other injuries" (28 {11%}), and abrasions/contusions (27 {11%}). Of the 233 reported illnesses, the most frequently reported were gastrointestinal (40 {17%}), rashes/dermatitis (38 {16%}), heat-related (31 {13%}), and "other conditions" (47 {20%}). Reported by: W Schmidt, MPH, M Skala, I Donelon, HD Donnell, Jr, MD, State Epidemiologist, Bur of Communicable Disease Control, Missouri Dept of Health. Emergency Response Coordination Group, and Disaster Assessment and Epidemiology Section, Health Studies Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health; Prevention Effectiveness Activity, Office of the Director, Div of Surveillance and Epidemiology, and Div of Field Epidemiology, Epidemiology Program Office; Div of Nutrition, National Center for Chronic Disease Prevention and Health Promotion; Div of Parasitic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The findings in this report are consistent with those in a previous report from Iowa that documented a substantial number of persons hospitalized for flood-related conditions (1). These findings underscore the importance of flood-related morbidity surveillance in assessing the need and planning for public health intervention measures.

The public health impact of floods and other disasters may reflect secondary effects of the disaster, such as population displacement and disruption of existing health services (2). In Missouri, although widespread flooding caused substantial population displacement, most persons displaced by the flood had access to health-care and medical services and to sanitary facilities throughout the impact phase. In addition, the findings of active surveillance at emergency shelters suggested that displaced persons were housed in shelters for only short periods and that they were able to secure temporary housing. During the recovery phase, most emergency shelters were not needed and were therefore closed.

In addition to guiding public health and health-care relief efforts, the findings in this report assisted public health officials in responding to public and media inquiries and will assist in planning surveillance strategies for future disasters. For example, the surveillance systems in Missouri were limited to shelters and emergency departments. However, to more accurately monitor flood-related morbidity in the future, surveillance will be expanded to include institutions and facilities that have been effective locations in previous flood disasters (e.g., relief agencies, outpatient medical clinics, disaster-assistance centers, state public health facilities, and physicians' offices) (3).


  1. CDC. Public health consequences of a flood disaster -- Iowa, 1993. MMWR 1993;42:653-6.

  2. Noji EK. Natural disasters. Crit Care Clin 1991;7:271-92.

  3. Western KA. Epidemiologic surveillance after natural disaster. Washington, DC: Pan American Health Organization, 1982:1-94; scientific publication no. 420.

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