Fig. 11.1.

Basic cholera model diagram. Individuals can be Susceptible to cholera, Exposed, Infectious (either symptomatically or asymptomatically), or Recovered (and immune to infection). Black arrows indicate transitions between these states. Infectious individuals shed cholera into the environment (indicated by the “+”s). Susceptible individuals become infected by exposure to Vibrio cholerae from the Environment (the ciclo largo route indicated by blue “x”) at the rate of β or “directly” from Infectious individuals at the rate of μ (the ciclo corto route indicated by green “x”s). After an incubation period, individuals transition from the Exposed to the Infectious state. Infectious individuals shed vibrios into the environment at rate ξ. Symptomatic and asymptomatic may have different levels of infectiousness, indicated by the subscripts following ξ and μ. Red arrows indicate possible effects of interventions labeled in italics, including vaccination, sanitation, and improved hygiene.