title: Flooding and emergency room visits for gastrointestinal illness in Massachusetts: a case-crossover study.
abstract: BACKGROUND
  Floods and other severe weather events are anticipated to increase as a result of global climate change. Floods can lead to outbreaks of gastroenteritis and other infectious diseases due to disruption of sewage and water infrastructure and impacts on sanitation and hygiene. Floods have also been indirectly associated with outbreaks through population displacement and crowding.
  
  
  METHODS
  We conducted a case-crossover study to investigate the association between flooding and emergency room visits for gastrointestinal illness (ER-GI) in Massachusetts for the years 2003 through 2007. We obtained ER-GI visits from the State of Massachusetts and records of floods from the National Oceanic and Atmospheric Association's Storm Events Database. ER-GI visits were considered exposed if a flood occurred in the town of residence within three hazard periods of the visit: 0-4 days; 5-9 days; and 10-14 days. A time-stratified bi-directional design was used for control selection, matching on day of the week with two weeks lead or lag time from the ER-GI visit. Fixed effect logistic regression models were used to estimate the risk of ER-GI visits following the flood.
  
  
  CONCLUSIONS
  A total of 270,457 ER-GI visits and 129 floods occurred in Massachusetts over the study period. Across all counties, flooding was associated with an increased risk for ER-GI in the 0-4 day period after flooding (Odds Ratio: 1.08; 95% Confidence Interval: 1.03-1.12); but not the 5-9 days (Odds Ratio: 0.995; 95% Confidence Interval: 0.955-1.04) or the 10-14 days after (Odds Ratio: 0.966, 95% Confidence Interval: 0.927-1.01). Similar results were observed for different definitions of ER-GI. The effect differed across counties, suggesting local differences in the risk and impact of flooding. Statewide, across the study period, an estimated 7% of ER-GI visits in the 0-4 days after a flood event were attributable to flooding.
authors.affiliation: United States Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Environmental Public Health Division, Chapel Hill, North Carolina, United States of America.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wade
authors.affiliation: Oak Ridge Institute for Science and Education (ORISE) Research Participation Program at the United States Environmental Protection Agency, Chapel Hill, North Carolina, United States of America; University of North Carolina, Gillings School of Global Public Health, Department of Epidemiology, Chapel Hill, North Carolina, United States of America.
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Lin
authors.affiliation: University of Illinois, Chicago, School of Public Health, Division of Environmental and Occupational Health Sciences, Chicago, Illinois, United States of America.
authors.forename: Jyotsna S
authors.initials: JS
authors.lastname: Jagai
authors.affiliation: United States Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Environmental Public Health Division, Chapel Hill, North Carolina, United States of America.
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Hilborn
mesh_terms: D018592:Cross-Over Studies; D004638:Emergency Treatment / Q000706:statistics & numerical data*; D055868:Floods / Q000266:history* / Q000706:statistics & numerical data*; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000209:etiology*; D049674:History, 21st Century; D006801:Humans; D016015:Logistic Models; D008404:Massachusetts / Q000453:epidemiology; D016017:Odds Ratio