In spite of local and international efforts to end the scourge of poliomyelitis in the world, the disease still exists around the world with new cases being detected in otherwise polio-free areas while the known endemic places of Asia and Sub-Saharan Africa are yet to be ridden of the epidemic. Knowing with accuracy whether the disease has finally ended in a population has always being a subject of interest to mathematicians, statisticians and epidemiologists. In this study, we have defined a conditional probability function xic(t) as the probability of zero transmission agents given that there are initially (i) symptomatic (ii) infectives and (iii) asymptomatic carriers. Using the properties of Poisson process, two backward equations were derived which were jointly solved numerically . With these numerical solutions, we were able to formulate a model for the two identified transmission agents of poliomyelitis.