El Niño−Southern Oscillation Variability and Its Effects on Cholera Occurrence Rates

A non-stationary climate imposes considerable challenges regarding potential public health concerns. Numerous studies have shown that the El Niño Southern Oscillation (ENSO), which occurs every two to seven years, is positively correlated with occurrences of the waterborne disease cholera. The warm sea surface temperatures and extreme weather associated with ENSO create optimal conditions for breeding of the Vibrio cholerae pathogen and for human exposure to the pathogenic waters. Here we explore the impacts of ENSO on cholera occurrence rates over the past fifty years by examining annual rates of suspected cholera cases per country in relation to ENSO Index values. This study provides a relationship indicating when hydrologic conditions are optimal for cholera growth, and presents a statistical approach to answer three questions: Are cholera outbreaks more likely to occur in an El Niño year? What other factors impact cholera outbreaks? How will climate in the future impact cholera incidences as it relates to ENSO? Cholera outbreaks from the 1960s through present day are examined focusing specifically in regions of Central and South America, and Southern Asia. By examining the predictive relationship between climate variability and cholera, we can draw conclusions about future vulnerability to cholera and other waterborne pathogenic diseases.