title: El Niño and the shifting geography of cholera in Africa.
abstract: The El Niño Southern Oscillation (ENSO) and other climate patterns can have profound impacts on the occurrence of infectious diseases ranging from dengue to cholera. In Africa, El Niño conditions are associated with increased rainfall in East Africa and decreased rainfall in southern Africa, West Africa, and parts of the Sahel. Because of the key role of water supplies in cholera transmission, a relationship between El Niño events and cholera incidence is highly plausible, and previous research has shown a link between ENSO patterns and cholera in Bangladesh. However, there is little systematic evidence for this link in Africa. Using high-resolution mapping techniques, we find that the annual geographic distribution of cholera in Africa from 2000 to 2014 changes dramatically, with the burden shifting to continental East Africa-and away from Madagascar and portions of southern, Central, and West Africa-where almost 50,000 additional cases occur during El Niño years. Cholera incidence during El Niño years was higher in regions of East Africa with increased rainfall, but incidence was also higher in some areas with decreased rainfall, suggesting a complex relationship between rainfall and cholera incidence. Here, we show clear evidence for a shift in the distribution of cholera incidence throughout Africa in El Niño years, likely mediated by El Niño's impact on local climatic factors. Knowledge of this relationship between cholera and climate patterns coupled with ENSO forecasting could be used to notify countries in Africa when they are likely to see a major shift in their cholera risk.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205.|Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556.|Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Moore
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Azman
authors.affiliation: Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Zaitchik
authors.affiliation: Division of Foodborne, Waterborne and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Mintz
authors.affiliation: Division of Foodborne, Waterborne and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329.
authors.forename: Joan
authors.initials: J
authors.lastname: Brunkard
authors.affiliation: Department of Pandemic and Epidemic Diseases, World Health Organization, 1211, Geneva, Switzerland.
authors.forename: Dominique
authors.initials: D
authors.lastname: Legros
authors.affiliation: Department of Pandemic and Epidemic Diseases, World Health Organization, 1211, Geneva, Switzerland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Hill
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205.
authors.forename: Heather
authors.initials: H
authors.lastname: McKay
authors.affiliation: Epicentre, 75012 Paris, France.|Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Luquero
authors.affiliation: Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205.
authors.forename: David
authors.initials: D
authors.lastname: Olson
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; justin@jhu.edu.
authors.forename: Justin
authors.initials: J
authors.lastname: Lessler
mesh_terms: D000349:Africa / Q000453:epidemiology; D002771:Cholera / Q000453:epidemiology*; D004196:Disease Outbreaks; D059000:El Nino-Southern Oscillation; D006801:Humans
keywords: Bayesian mapping; El Niño Southern Oscillation; cholera; climate and health; disease mapping