Table 1. Case definition and ascertainment of acute flaccid paralysis cases, United Kingdom, 1 January 2018–21 January 2019.

Case definition			Number of cases
Acute flaccid paralysis	Clinical	Any person presenting with symptoms of AFP not explained by a non-infectious cause	40
	Discarded	Not AFP OR AFP explained by a non-infectious cause	0
Poliomyelitis	Poliomyelitis-confirmed	AFP case in whom poliovirus was detected	0
	Pending	AFP case with inadequate specimens or samples not yet tested and/or 60 day follow-up not completed	2
	Poliomyelitis-discarded	AFP case where poliovirus infection was unlikely after expert review based on clinical, epidemiological and virological information	38
Acute flaccid myelitis	Probable	Any person with symptoms of acute flaccid limb paralysis AND CSF showing pleocytosis (WCC > 5 cells/mm3)	7
	Confirmed	Any person with symptoms of acute flaccid limb paralysis AND An MRI showing a spinal cord lesion largely restricted to grey matter spanning ≥ 1 spinal segments	9
	Pending	Any person with symptoms of acute flaccid limb paralysis AND An MRI unavailable or results need clarification	19
	Discarded	Any person with symptoms of acute flaccid limb paralysis AND MRI findings inconsistent with AFM	5
Non-polio enteroviral associated AFP	Confirmed	AFP case where non-polio enterovirus was detected in one or more sample (respiratory, stool, CSF)	15
	Negative	AFP case where non-polio enterovirus was not detected in appropriately timed samples (respiratory, stool, CSF taken within 14 days of illness onset)	8
	Pending	AFP case where specimens not taken or samples not yet tested	10
	Unexplained	AFP case where inadequate specimens available	7

AFM: Acute flaccid myelitis; AFP: acute flaccid paralysis; CSF: cerebral spinal fluid; MRI: magnetic resonance imaging; WCC: white cell count.