Vaccine-Related Poliomyelitis

Immunization has virtually eliminated wild-type poliovirus in this country, but polio still occurs as an iatrogenic disease from the oral trivalent vaccine.¹ The risk is small—about one paralytic case per 3 to 4 million units of live vaccine distributed, or less than 20 cases yearly. History of exposure may be unknown or forgotten, since most cases occur in nonimmune adults who contact the virus from oral secretions or the stool of vaccine recipients. Unwary physicians trained in the postvaccine era may misdiagnose polio as the Guillain-Barré syndrome. Clinical features that should argue against Guillain-Barré syndrome are absence of sensory symptoms, prominent meningeal signs, fever at onset of paralysis, and pleocytosis of greater than 50 cells.² Electrodiagnostic tests also are useful in this differentiation. In polio, sensory nerve conduction velocities are normal, and motor conductions are either normal or, in severe cases, absent because of segmental anterior horn cell