Climate and cholera in KwaZulu-Natal, South Africa: the role of environmental factors and implications for epidemic preparedness.

A cholera epidemic that took place in KwaZulu-Natal, South Africa (2000-2001) was employed to investigate the impact of climatic and environmental drivers on cholera dynamics. Precipitation (PRE), sea surface temperature (SST) and chlorophyll-a (CHL-a) data acquired from publicly available satellite and ground measurements were analysed together with disease incidence in an effort to assess the environmental contribution to the outbreak. SST (r(2)=0.749, lag=0 months) and PRE (r(2)=0.744, lag=2 months) showed strong associations with incidence. CHL-a showed a moderately strong (r(2)=0.656, lag=6 months) association with incidence while sea surface height (SSH) demonstrated a weak relationship with incidence (r(2)=0.326, lag=5 months). Our analysis tentatively supports a coastal transmission hypothesis, heavily influenced by localized PRE extremes. The role of SSH is likely attenuated by local coastal topography. Future work should clarify the mechanism linking coastal cholera reservoirs and the regional climate system to outbreaks in this region. Finally, we discuss benefits of further research in this area using extended remotely sensed and epidemiological datasets towards the development of early-warning systems and enhanced epidemic preparedness.