title: Examining rainfall and cholera dynamics in Haiti using statistical and dynamic modeling approaches.
abstract: Haiti has been in the midst of a cholera epidemic since October 2010. Rainfall is thought to be associated with cholera here, but this relationship has only begun to be quantitatively examined. In this paper, we quantitatively examine the link between rainfall and cholera in Haiti for several different settings (including urban, rural, and displaced person camps) and spatial scales, using a combination of statistical and dynamic models. Statistical analysis of the lagged relationship between rainfall and cholera incidence was conducted using case crossover analysis and distributed lag nonlinear models. Dynamic models consisted of compartmental differential equation models including direct (fast) and indirect (delayed) disease transmission, where indirect transmission was forced by empirical rainfall data. Data sources include cholera case and hospitalization time series from the Haitian Ministry of Public Health, the United Nations Water, Sanitation and Health Cluster, International Organization for Migration, and Hôpital Albert Schweitzer. Rainfall data was obtained from rain gauges from the U.S. Geological Survey and Haiti Regeneration Initiative, and remote sensing rainfall data from the National Aeronautics and Space Administration Tropical Rainfall Measuring Mission. A strong relationship between rainfall and cholera was found for all spatial scales and locations examined. Increased rainfall was significantly correlated with increased cholera incidence 4-7 days later. Forcing the dynamic models with rainfall data resulted in good fits to the cholera case data, and rainfall-based predictions from the dynamic models closely matched observed cholera cases. These models provide a tool for planning and managing the epidemic as it continues.
authors.affiliation: Mathematical Biosciences Institute, The Ohio State University, United States; Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, United States; Department of Mathematics, University of Michigan, Ann Arbor, United States. Electronic address: marisae@umich.edu.
authors.forename: Marisa C
authors.initials: MC
authors.lastname: Eisenberg
authors.forename: Gregory
authors.initials: G
authors.lastname: Kujbida
authors.forename: Ashleigh R
authors.initials: AR
authors.lastname: Tuite
authors.forename: David N
authors.initials: DN
authors.lastname: Fisman
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Tien
mesh_terms: D002771:Cholera / Q000453:epidemiology* / Q000635:transmission; D006205:Haiti / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008432:Mathematical Computing; D015233:Models, Statistical; D011891:Rain; D012424:Rural Population / Q000706:statistics & numerical data*; D012621:Seasons; D014505:Urban Population / Q000706:statistics & numerical data*
keywords: Cholera; Haiti; Mathematical modeling; Rainfall; Waterborne diseases