摘要：Objectives. We investigated increases in diarrheal illness detected through syndromic surveillance after a power outage in New York City on August 14, 2003. Methods. The New York City Department of Health and Mental Hygiene uses emergency department, pharmacy, and absentee data to conduct syndromic surveillance for diarrhea. We conducted a case–control investigation among patients presenting during August 16 to 18, 2003, to emergency departments that participated in syndromic surveillance. We compared risk factors for diarrheal illness ascertained through structured telephone interviews for case patients presenting with diarrheal symptoms and control patients selected from a stratified random sample of nondiarrheal patients. Results. Increases in diarrhea were detected in all data streams. Of 758 patients selected for the investigation, 301 (40%) received the full interview. Among patients 13 years and older, consumption of meat (odds ratio [OR]=2.7, 95% confidence interval [CI]=1.2, 6.1) and seafood (OR=4.8; 95% CI=1.6, 14) between the power outage and symptom onset was associated with diarrheal illness. Conclusions. Diarrhea may have resulted from consumption of meat or seafood that spoiled after the power outage. Syndromic surveillance enabled prompt detection and systematic investigation of citywide illness that would otherwise have gone undetected. At 4:11 pm Eastern daylight savings time on August 14, 2003, an estimated 60 million people in 8 US states and 1 Canadian province (Ontario) experienced a sudden, massive power outage. 1 An estimated 9 million people in the New York City metropolitan area were affected. Electric power was unavailable in New York City from several hours to more than 2 days in some locations. The New York City Department of Health and Mental Hygiene (DOHMH) activated its emergency response system to address various public health concerns arising from the power outage. 2 One concern was the potential for illness from the consumption of food from refrigerators that had been without power. Microbial pathogens can multiply in food to sufficient concentrations to cause gastrointestinal illness in as few as 2 hours at 41°F. 3 , 4 DOHMH released 3 health alerts within 24 hours of the blackout urging the public to avoid eating foods prone to spoilage and immediately discard them. Alerts were sent to health providers recommending that they lower thresholds for collecting specimens for diagnostic testing in patients with diarrheal illness and that they advise parents of ill children to exclude children from child care and other group settings until the diarrhea resolved. Syndromic surveillance systems are designed to detect increases and clustering of clinical syndromes representing natural or bioterrorism-related illnesses. 5 , 6 Four data sources used to monitor trends in syndromes in New York City (emergency department [ED] visits, pharmacy sales data from 2 sources, employee absenteeism) provide syndromic data indicative of diarrheal illness. A fifth data source (emergency medical service calls) does not contain data that indicate diarrheal syndromes. Syndromic data are transmitted and analyzed daily so aberrant patterns in illnesses of public health concern can be rapidly detected and promptly investigated. 7 – 9 On August 15, 2003, despite the loss of power, the DOHMH received electronic files containing data for the previous day’s ED visits from 9 of 41 hospitals through a wireless laptop computer operated from a gas-powered generator. DOHMH staff traveled to 29 EDs, where they reviewed medical records, tallied chief complaints by syndrome, and reported tallies to a central location. Tallies were entered manually and combined with the electronic data for routine daily analysis; concerning patterns were investigated immediately. On August 16, data were transmitted electronically from 13 hospitals. An additional 15 hospitals faxed paper chief complaint logs that were manually entered and combined with electronic data for routine analysis. On August 17, electronic data transmission was restored for 29 hospitals, and manual entry was discontinued. During the 3 days after the power outage, increases in diarrheal illness were detected in each of the 4 syndromic data sources used to monitor diarrheal illness. This was the first time in 2 years of operations that an increase in a single syndrome was detected in every applicable data source. This increase was not reported through any other mechanism. In response, we conducted a case–control investigation to determine risk factors for diarrheal illness after the blackout.
