Paralytic vs. "nonparalytic" polio: distinction without a difference?

Abstract

Nonparalytic polio (NPP) is commonly thought to be synonymous with "abortive polio," in which the poliovirus neither entered the central nervous system nor damaged neurons. Described are two epidemic illness-"The Summer Grippe" and Iceland disease-apparently caused by a low virulence but neuropathic type 2 poliovirus. Studies show that neuronal lesions in the brain and spinal cord and muscle weakness were common in NPP, and epidemiologic studies document late-onset weakness and fatigue in 14% to 42% of NPP survivors. These findings indicate that clinicians should not require a history of paralytic polio, electromyographic evidence of denervation, and new muscle weakness for the diagnosis of "Postpolio Syndrome" but should be aware that NPP, and possibly even poliovirus-induced "minor illnesses," can be associated with acute central nervous system damage and late-onset muscle weakness and fatigue.