What drives cholera: environment or humans or both?

Cholera remains a dreadful water-related disease of the developing world. Although mortality rates from cholera are low in endemic regions, yet a sudden emergence of disease in an unknown region, results in a widespread loss of human lives. A recent outbreak in Haiti is an example, where more than 60000 people were directly affected from cholera in 2010. Plausible arguments are made for environmental transmission of cholera where large scale geophysical processes such as river discharge, droughts, floods, sea surface temperature create conditions favorable for bacterial growth, that, in combination with proper transmission mechanisms result in disease outbreak. Critics to the environmental transmission argue that the origin of cholera in a given spatial and temporal regime is a result of human-to human interaction that may overshadows any preceding environmental conditions. Here, using mathematical SEIR model, we show that a combination of environment and human interactions leads to a cholera epidemic. Primary outbreak of cholera is driven by the large scale hydroclimatological forcings (primarily droughts and floods) whereas secondary transmission driven by human networks. We will also present scenarios on controlling the spread of disease once the primary outbreak occur. Since the bacteria remains in the environment, efforts should be concentrated to develop a prediction mechanism of an impending outbreaks and thereafter monitoring the population for possible human-to-human transmission.