Simulation of a community that experiences seasonal contact with contaminated waters (due to periodic flooding, for example). Periodic fluctuation of the contact rate causes oscillations in the number of infections. During the low contact period, no infections occur. As contact increases (due to rising waters in a flooding area, for example), the probability of catching cholera increases. Outbreaks tend to occur sooner in larger populations. Dot-dashed line shows the number of infections in a population with 1,000 individuals, dashed line in a 5,500 population and dotted line in a 100,000 population. In large populations, the seasonal outbreak may be followed by a period with relatively constant incidence as contact rate continues high.