The mathematical analysis of concurrent epidemics of yaws and chickenpox

Abstract

The relationship between chickenpox and yaws epidemics occurring among children in a village in Netherlands New Guinea is analysed using the mathematical model for a simple deterministic epidemic. It is shown that the yaws epidemic accelerated significantly in the month following the chickenpox epidemic, but that it reverted to its previous rate in the succeeding months. The number of yaws cases attributable to the influence of the chickenpox is estimated from the projected course of the yaws epidemic. It is statistically verified that those children contracting chickenpox were more likely to become yaws cases in the subsequent month.These results point to the danger of yaws's spread being much more rapid among a population which has recently been subject to an epidemic of chickenpox.