English: Graph showing the seasonal nature of the occurrence of " acute flaccid myelitis "(AFM), a rare but serious neurologic illness of sudden onset, usually in children. It presents with localised limb weakness of unknown cause. A leading candidate for the cause of the condition is enterovirus 68, a member of the enterovirus genus and thus related to poliovirus. Although the illness is not new, its increased incidence since 2014 is new; the existing literature about it is tentative and should not be taken as established medical opinion.