Diarrheal illness detected through syndromic surveillance after a massive power outage: New York City, August 2003.

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.