title: Indian Ocean dipole and rainfall drive a Moran effect in East Africa malaria transmission.
abstract: BACKGROUND
  Patterns of concerted fluctuation in populations-synchrony-can reveal impacts of climatic variability on disease dynamics. We examined whether malaria transmission has been synchronous in an area with a common rainfall regime and sensitive to the Indian Ocean Dipole (IOD), a global climatic phenomenon affecting weather patterns in East Africa.
  
  
  METHODS
  We studied malaria synchrony in 5 15-year long (1984-1999) monthly time series that encompass an altitudinal gradient, approximately 1000 m to 2000 m, along Lake Victoria basin. We quantified the association patterns between rainfall and malaria time series at different altitudes and across the altitudinal gradient encompassed by the study locations.
  
  
  RESULTS
  We found a positive seasonal association of rainfall with malaria, which decreased with altitude. By contrast, IOD and interannual rainfall impacts on interannual disease cycles increased with altitude. Our analysis revealed a nondecaying synchrony of similar magnitude in both malaria and rainfall, as expected under a Moran effect, supporting a role for climatic variability on malaria epidemic frequency, which might reflect rainfall-mediated changes in mosquito abundance.
  
  
  CONCLUSIONS
  Synchronous malaria epidemics call for the integration of knowledge on the forcing of malaria transmission by environmental variability to develop robust malaria control and elimination programs.
authors.affiliation: Graduate School of Environmental Sciences and Global Center of Excellence Program on Integrated Field Environmental Science, Hokkaido University, Sapporo, Japan. lchaves@ees.hokudai.ac.jp
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Chaves
authors.forename: Akiko
authors.initials: A
authors.lastname: Satake
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hashizume
authors.forename: Noboru
authors.initials: N
authors.lastname: Minakawa
mesh_terms: D000351:Africa, Eastern / Q000453:epidemiology; D002980:Climate; D006801:Humans; D019156:Indian Ocean; D008288:Malaria / Q000453:epidemiology* / Q000635:transmission*