EcoHealth

, Volume 4, Issue 1, pp 52–62

Cholera Seasonality in Madras (1901–1940): Dual Role for Rainfall in Endemic and Epidemic Regions

  • Diego Ruiz-Moreno
  • Mercedes Pascual
  • Menno Bouma
  • Andrew Dobson
  • Benjamin Cash
Original Contributions

DOI: 10.1007/s10393-006-0079-8

Cite this article as:
Ruiz-Moreno, D., Pascual, M., Bouma, M. et al. EcoHealth (2007) 4: 52. doi:10.1007/s10393-006-0079-8

Abstract

The seasonality of cholera and its spatial variability remain unexplained. Uncovering the role of environmental drivers in these seasonal patterns is critical to understand temporal variability at longer time scales, including trends and interannual variability. Rainfall has been proposed as a key driver of the seasonality of cholera. To address this hypothesis, we examine the association between rainfall and cholera in both time and space using the extensive historical records for the districts of Madras in former British India (1901–1940). We show the existence of two main spatial clusters that differ not just in the effect of rainfall but also in the seasonal pattern and frequency of periods with and without cholera mortality. The results support a model of cholera seasonality with two different routes of transmission: one is enhanced by increasing rainfall (in areas with abundant water), the other is buffered by increasing water. We discuss how the dual nature of the influence of rainfall creates different temporal patterns in regions where cholera is either “endemic” or “epidemic.”

Keywords

Choleraendemic choleraepidemic cholerarainfall

Copyright information

© Ecohealth Journal Consortium 2007

Authors and Affiliations

  • Diego Ruiz-Moreno
    • 1
  • Mercedes Pascual
    • 1
  • Menno Bouma
    • 2
  • Andrew Dobson
    • 3
  • Benjamin Cash
    • 4
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborUSA
  2. 2.Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical MedicineUniversity of LondonLondonUK
  3. 3.Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonUSA
  4. 4.Center for Ocean–Land–Atmosphere StudiesCalvertonUSA