Examining the probability of silent circulation of polio using the endemic potential statistic

Polio is a fecal-oral disease that can cause fever and flu-like symptoms, and, in more rare instances, acute flaccid paralysis (AFP). One characteristic of poliovirus is asymptomatic transmission amongst individuals who have already had a poliovirus infection. This allows the virus to silently circulate in an endemic population unless a surveillance system is put into place. Eradication efforts have reduced the regions of endemic circulation down to three localities. However, due to infrequent first infections and poor surveillance, it can be difficult to determine when the virus has been eliminated from the population. The endemic potential statistic is used to determine the probability of polio circulation given t years without a detected paralytic case. In this talk, we will critically examine the nuances of the endemic potential statistic as well as the effect of model assumptions, using a discrete-individual stochastic counting process model of polio. In addition, we will extend the model to include multiple villages. Using the endemic potential statistic, we will show that the long-term probability of circulation is higher in isolated villages than in non-isolated villages.