Background Microbiology Single-stranded, positive-sense, unenveloped RNA virus in the family Picornaviridae , genus Enterovirus , species Enterovirus C
Currently, the most common cause of poliomyelitis is oral vaccine-derived poliovirus Pathophysiology Targets the spinal anterior horn cells Clinical Manifestations 90-95% of cases are clinically inapparent; 4-8% are abortive after the prodrome; and only 1-2% proceed to major illness
Incubation period of 9 to 12 days (range 5 to 35 days) before onset of prodrome
Minor illness lasts a few days
Fever, headache, sore throat, malaise, anorexia, vomiting, or abdominal pain
Normal neurological exam Spinal Paralytic Poliomyelitis 0.1% of all poliovirus infection
2 to 5 days after resolution of minor illness, onset of aseptic meningitis, with fever, headache, nuchal rigidity, vomiting, and a CSF pleocytosis
Weakness and paralysis start within a few days
Asymmetric, flaccid paralysis with increased DTRs
Typically proximal more than distal muscles, and legs more than arms
Typical pattern is one leg then one arm, or both legs then both arms
Progresses to complete paralysis over 2 to 3 days
Rarely sensory loss; if present, consider another diagnosis such as Guillain-Barré syndrome Bulbar Paralytic Poliomyelitis Represents 5 to 25% of paralytic poliomyelitis during outbreaks
Affects the cranial nerves, presenting with dysphagia, nasal speech, and dyspnea
Pooling saliva Polioencephalitis Uncommon
Presents like any other cause of encephalitis
Confusion, altered level of consciousness, and seizure
May have spastic paralysis rather than flaccid Postpoliomyelitis Syndrome See post-polio syndrome
Median latency 36 years after an episode of paralytic poliomyelitis
New onset weakness, pain, atrophy, and fatigue
Can affect the respiratory muscles Differential Diagnosis Paralytic poliomyelitis: other causes of acute flaccid paralysis
Other enteroviruses, such as enterovirus A-71, enterovirus D-68
West Nile virus Guillain-Barré syndrome , which would be symmetrical, bilateral ascending paralysis with loss of sensation, that progresses over 1 to 2 week and has minimal CSF pleocytosis with albuminocytologic dissociation
Polioencephalitis: other causes of encephalitis Diagnosis PCR is the only way to distinguish between wildtype polio and vaccine-derived
Throat swabs during the first week of illness
Feces for several weeks
CSF not particularly sensitive, but is helpful when positive and should still be sent
Acute and convalescent serology Management
