title: A differential effect of Indian ocean dipole and El Niño on cholera dynamics in Bangladesh.
abstract: BACKGROUND
  A stationary (i.e., constant through time) association between El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD) and epidemics of cholera in Bangladesh has been widely assumed. However, whether or not elements of the local climate that are relevant for cholera transmission have stationary signatures of the IOD on their dynamics over different time scales is still not clear. Here we report results on the time-varying relationships between the various remote and local environmental drivers and cholera incidence in Bangladesh.
  
  
  RESULTS
  We performed a cross wavelet coherency analysis to examine patterns of association between monthly cholera cases in the hospitals in Dhaka and Matlab (1983-2008) and indices for both IOD and ENSO. Our results showed that the strength of both the IOD and ENSO associations with cholera hospitalizations changed across time scales during the study period. In Dhaka, 4-year long coherent cycles were observed between cholera and the index of IOD in 1988-1997. In Matlab, the effect of ENSO was more dominant while there was no evidence for an IOD effect on cholera hospitalizations.
  
  
  CONCLUSIONS
  Our results call for the consideration of non-stationary, possibly non-linear, patterns of association between cholera hospitalizations and climatic factors in cholera epidemic early warning systems.
authors.affiliation: Institute of Tropical Medicine (NEKKEN) and the Global Center of Excellence program, Nagasaki University, Nagasaki, Japan. hashizum@nagasaki-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hashizume
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Chaves
authors.forename: A S G
authors.initials: AS
authors.lastname: Faruque
authors.forename: Md
authors.initials: M
authors.lastname: Yunus
authors.forename: Kim
authors.initials: K
authors.lastname: Streatfield
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Moji
mesh_terms: D001459:Bangladesh / Q000453:epidemiology; D002771:Cholera / Q000453:epidemiology*; D002980:Climate; D059000:El Nino-Southern Oscillation; D058872:Epidemics; D006801:Humans; D019156:Indian Ocean
references.citation: Proc Natl Acad Sci U S A. 2002 Oct 1;99(20):12901-6
references.pmid: 12228724
references.citation: PLoS Med. 2006 Aug;3(8):e295
references.pmid: 16903778
references.citation: Br Med J (Clin Res Ed). 1982 Oct 23;285(6349):1185-8
references.pmid: 6812801
references.citation: BMC Infect Dis. 2007 Mar 19;7:20
references.pmid: 17371602
references.citation: J Diarrhoeal Dis Res. 1994 Jun;12(2):87-96
references.pmid: 7963350
references.citation: Epidemiology. 2010 Sep;21(5):706-10
references.pmid: 20562706
references.citation: Science. 1996 Dec 20;274(5295):2025-31
references.pmid: 8953025
references.citation: Emerg Infect Dis. 2007 May;13(5):681-6
references.pmid: 17553244
references.citation: Lancet. 2003 May 17;361(9370):1705-6
references.pmid: 12767739
references.citation: Environ Health Perspect. 2011 Feb;119(2):239-44
references.pmid: 20980219
references.citation: N Engl J Med. 2006 Aug 17;355(7):649-51
references.pmid: 16914700
references.citation: J Trop Med Hyg. 1989 Dec;92(6):396-401
references.pmid: 2607573
references.citation: Clin Microbiol Rev. 2002 Oct;15(4):757-70
references.pmid: 12364378
references.citation: Sci Rep. 2012;2:269
references.pmid: 22355781
references.citation: Epidemiology. 2008 Jan;19(1):103-10
references.pmid: 18091420
references.citation: Science. 1977 Oct 28;198(4315):394-6
references.pmid: 910135
references.citation: Am J Trop Med Hyg. 2011 Aug;85(2):303-8
references.pmid: 21813852
references.citation: Nature. 1999 Sep 23;401(6751):356-60
references.pmid: 16862107
references.citation: Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1438-43
references.pmid: 10677480
references.citation: Nature. 1999 Sep 23;401(6751):360-3
references.pmid: 16862108
references.citation: Public Health Rep. 1960 Sep;75:791-803
references.pmid: 13810825
references.citation: Proc Natl Acad Sci U S A. 2005 Feb 1;102(5):1702-7
references.pmid: 15653771
references.citation: PLoS Negl Trop Dis. 2007 Oct 22;1(1):e33
references.pmid: 17989780
references.citation: Proc Natl Acad Sci U S A. 2008 Nov 18;105(46):17676-81
references.pmid: 19001267
references.citation: Nature. 2008 Aug 14;454(7206):877-80
references.pmid: 18704085
references.citation: Appl Environ Microbiol. 1983 Jan;45(1):275-83
references.pmid: 6337551
references.citation: PLoS Negl Trop Dis. 2010 Jul 13;4(7):e747
references.pmid: 20644621
references.citation: Nature. 2005 Aug 4;436(7051):696-700
references.pmid: 16079845
references.citation: PLoS Med. 2005 Apr;2(4):e106
references.pmid: 15839751
references.citation: Science. 2000 Sep 8;289(5485):1766-9
references.pmid: 10976073