Fifteen years of acute flaccid paralysis surveillance in Hong Kong: Findings from 1997 to 2011

Aim: Acute flaccid paralysis (AFP) surveillance system was set up in Hong Kong in 1997 for World Health Organization's (WHO) certification of poliomyelitis eradication. This paper describes and reviews the demographic, clinical and virological characteristics of AFP cases reported to the system in its first 15 years. Methods: All patients aged under 15 years presented with acute onset of paralysis of any limbs reported to the Department of Health from January 1997 to December 2011 were reviewed. Data on demographic characteristics, vaccination history, clinical presentation and virological investigation on stool specimens collected during investigation were analysed with descriptive statistics. Results: Of the 247 cases reported, about 45% were aged under five. All cases were classified as non-polio AFP according to WHO classification. About 60% were identified with neurological disorders, with Guillain-Barr syndrome (25.9%) and myelitis (13.4%) being the most common. Viruses were detected in 14.0% of the AFP cases, with non-polio enteroviruses (NPEV) (60.0%) and adenoviruses (31.4%) accounted for most of the positive detections. Most performance indicators set by the WHO were fulfilled. Conclusions: The AFP surveillance facilitated the clinical, virological and epidemiological examination of paediatric AFP cases. From 1997 to 2011, Guillain-Barr syndrome and myelitis were the most common among paediatric AFP cases in Hong Kong. NPEV and adenoviruses accounted for most of the positive viral detections. No wild poliovirus was detected, and all cases were classified as non-polio AFP.