Cholera, a waterborne disease transmitted by the bacteria Vibrio cholerae, infects millions around the world every year, with the greatest burden in Africa. In 2014, Africa accounted for 55% of global suspected cholera cases reported to the World Health Organization (WHO) Global Health Observatory. In addition, the case fatality ratio for cholera in Africa is approximately twice the WHO-threshold indicative of adequate quality case management. The actual number of cholera cases and deaths is difficult to judge on account of under-reporting, but recent estimates from our group based on a large corpus of cholera incidence data from multiple sources suggest that more than 80 million people are at high risk of cholera in sub-Saharan Africa.

Cholera has long been described as a climate-sensitive disease, and predictive models have been proposed in coastal environments (primarily in Asia) where cholera appears to respond to SST situation is more complicated, as the majority of cholera cases occur inland, far from the coasts, and as the sensitivity of cholera incidence to climate variability varies by climatic context in some places excess precipitation can trigger an outbreak, while in others cholera tends to spike during drought. In a recent analysis of cholera across the African continent we quantified these contextual and non-linear climate responses and described potentially predictive relationships between ENSO, local climate variability and the geographic distribution of cholera. Here we propose to work with the WHO’s Global Task Force on Cholera Control (GTFCC) to apply these findings to create an operational African Cholera Risk Early Warning System (ACREWS) that can inform deployment of resources for cholera control. Recognizing the multiple sources of uncertainty in cholera risk mapping, we will generate a suite of products: (1) a cholera environmental potential monitor based on Earth Observation monitoring products and static risk factors; (2) a cholera risk monitor that includes consideration of disease transmission dynamics; (3) a cholera risk outlook that extends the risk monitor on the basis of known environmental teleconnections; (4) a full cholera risk forecast that produces season-ahead risk estimates using downscaled seasonal forecast information and dynamic hydrological and disease models. The purpose of this suite of products is to evaluate tradeoffs between potential value to decision makers which increases with completeness and lead time􀁉and uncertainty in the system.

ACREWS products will be optimized and communicated in collaboration with GTFCC to ensure that the system provides adequate information content for cholera prevention decisions. GTFCC will also aid in the final selection of useful products and will communicate and disseminate forecasts through their network of cholera response professionals.