Retrospective hospital-based searches for cases of acute flaccid paralysis

Objective: Australia had to demonstrate adequate acute flaccid paralysis (AFP) surveillance by achieving a rate of one per 100,000 in children under the age of 15 to fulfil one of the requirements of the Regional Commission for the Certification of Poliomyelitis Eradication to be declared polio free. To increase the ascertainment rate of AFP cases, a hospital search was conducted to identify cases not reported to the active AFP surveillance. Methods: A computerised search of hospital admissions in New South Wales (NSW) and Western Australia (WA) on ICD-9 codes of Guillain Barré Syndrome (GBS), unspecified encephalitis, poliomyelitis, vaccine-associated paralytic polio (VAPP) and flaccid paralysis was conducted for the period 1995-98. Medical records of cases that were not reported to the active surveillance were reviewed in three hospitals of NSW and two hospitals in WA. Results: Twenty additional cases recorded as GBS and five as transverse myelitis (TM) were identified through the searches, which increased the average four-year AFP rate from 1.0 to 1.4 per 100,000 in children under the age of 15 years in these two states and the overall AFP rate in Australia increased from 0.78 to 1.14. There were no cases of polio or VAPP found. Nine cases of GBS and five of TM reported to the active AFP surveillance were not found in the hospital searches. Conclusion: A combination of active surveillance and hospital-based searches increased the investigated AFP rate, which fulfilled one of the certification requirements for Australia to be certified polio free. Implications: Until global certification is achieved, AFP surveillance needs to be improved to identify cases of importation of wild poliovirus.