PARENT SESSION
Session #11: The role of parasites and infectious diseases in ecology. Organized by: A. Dobson, L. Real, R. Ostfeld, and R. Holt.
Tuesday, August 7, 2001. Madison Ballroom A
Synchronicity, temporal scales, and the role of an environmental reservoir in cholera dynamics.
Pascual, Mercedes1, Roy, Manojit1, Dobson, Andrew2, Rodo, Xavier3, Bouma, Menno4, 1 2 3 4
ABSTRACT- The gradual recognition over the last decades that the pathogen Vibrio cholerae inhabits estuaries and brackish waters, often in association with plankton, underlies current debates on the role of a coastal environmental reservoir and climatic variability in cholera dynamics. Cholera variability in endemic regions exhibits pronounced seasonal and interannual cycles in both past and recent records. ENSO has been shown to influence this interannual variability, and Sea Surface Temperature (SST) in coastal environments has been proposed as an important variable mediating this effect locally and driving seasonality. If SST and the marine reservoir of V. cholerae initiate responses to climate forcing, epidemics in coastal areas and estuaries should anticipate those inland. This study investigates the synchronicity of cholera outbreaks at seasonal and interannual time scales in historical records for former Bengal, the homeland of the disease. Wavelet analysis is used to address phase differences in cholera mortality at specific time scales for the different districts and relative to the coast. Two large regions of coherent temporal dynamics are identified and discussed in relation to geography. An extension of the SIR model is presented to further address the role of an aquatic reservoir in cholera dynamics.
KEY WORDS: synchronicity, temporal scales, cholera dynamics