The diffusion of cholera outside Ibadan City, Nigeria, 1971.

This paper examined the spread of cholera epidemic to the towns of the former Western State of Nigeria and to the neighbouring villages of Ibadan after the initial introduction of the disease to Ibadan city by early January, 1971). In the diffusion process, an hierarchical diffusion was discovered at the town-village dichotomy while a distance decay function was justified at the purely urban level analyses. In the spread of cholera to all the surrounding villages of Ibadan, the epidemic speed was discovered to be too rapid that neither population size nor distance from Ibadan was relevant to the pattern of spread. The rate of cholera infection was observed to decline with distance from the city of Ibadan, while the duration of the epidemic obeyed the rank-size principles.