Staying polio free: A capture-recapture analysis of acute flaccid paralysis surveillance in the Australian Capital Territory

Abstract

Objective: Detections of acute flaccid paralysis in the Australian Capital Territory in the last decade have been lower than the target rate for polio surveillance. The aim of this study was to evaluate the case ascertainment of acute flaccid paralysis surveillance in the Australian Capital Territory to determine if cases have been under-reported. Methods: A two-source capture-recapture analysis was designed to estimate the number of acute flaccid paralysis cases in the Australian Capital Territory population aged under 15 years from 2000 to 2021 using 1) the National Acute Flaccid Paralysis Surveillance Database (the database) and 2) Canberra Hospital inpatient records. Results: The capture-recapture analysis estimated there were 26 acute flaccid paralysis cases in the Australian Capital Territory during this period (95% confidence interval: 8–43), with estimated 27% case ascertainment by the database. Conclusions: Under-reporting of non-polio acute flaccid paralysis in the Australian Capital Territory was identified. Lack of awareness of acute flaccid paralysis surveillance requirements among clinicians and a lack of dedicated surveillance resources may have contributed to under-reporting. Acute flaccid paralysis reporting mechanisms should be reviewed in partnership with local clinicians to ensure that all acute flaccid paralysis cases are detected and investigated for possible poliovirus infection. Implications for Public Health: Acute flaccid paralysis surveillance needs to be homogenously robust so that public health response can be rapidly initiated if polio is reintroduced in Australia.