Snapshot A 4-year-old girl presents to a local hospital in Pakistan with sudden onset of leg weakness. Parents report patient had fever and diarrhea one week prior which has since resolved. There is no history of immunization. Physical exam revealed a flaccid paralysis in both lower limbs which is more marked on the right than the left. Deep tendon reflexes are absent and sensation is intact. Introduction Classification virus RNA linear, single-stranded (+) picornavirus poliovirus Highly infectious viral disease causative agent of poliomyelitis (aka infantile paralysis) strictly a human pathogen that does not infect other species poliovirus is an enterovirus fecal-oral transmission paralytic poliomyelitis occurs in < 1% of infections poliomyelitis is a CNS disease LMN lesions only, due to destruction of anterior horns flacid paralysis Epidemiology incidence 223 reported cases in 2012 cases have decreased by > 99% since 1988 95% of cases are asymptomatic risk factors mainly affects children < 5-years-old location Afghanistan, Nigeria, and Pakistan Mechanism and pathophysiology virus enters via fecal-oral route multiplies in intestines and oropharynx presence of CD155 defines the tissues that can be infected by poliovirus paralytic disease virus enters CNS via bloodstream and replicates in motor neurons < 3 % of infections leads to selective destruction of motor neurons of anterior horn of spinal cord lower motor neuron death resultant temporary or permanent paralysis paralysis can lead to respiratory arrest and death Presentation Symptoms minor fever fatigue headache vomiting myalgias CNS disease most are nonparalytic aseptic meningitis headache neck pain back pain fever abdominal and extermity pain paralytic disease muscle pain and spasms hypotonia atrophy fasciculations hyporeflexia weakness and paralysis - acute flaccid paralysis encephalitis (rare) Evaluation Labs recover poliovirus from stool sample or pharynx swab serology antibodies to poliovirus Diagnosis clinical suspect in patient with acute onset flaccid paralysis absent DTRs absence of sensory or cognitive loss CSF increased WBCs - primarily lymphocytes slight elevation of protein no change in glucose PCR amplification Differential Guillain-Barré syndrome Other motor polyneuropathies Acute meningitides Treatment Supportive care no specific cures have been developed hospitalization as needed antibiotics to prevent infections in weakened muscles analgesics for pain ventilatory support as needed long-term rehab including PT/OT braces corrective shoes sometimes orthopedic surgery Prognosis, Prevention and Complications Prognosis 1 in 200 infections lead to permanent paralysis Prevention vaccines efficiently block person-to-person transmission of the virus 2 types Sabin's polio virus live, attenuated induces mainly cell-mediated immunity OPV - oral polio vaccine rarely to a form that can cause paralysis Salk's polio virus killed virus induces mainly humoral immunity IPV - inactivated polio vaccine cannot revert to a form that can cause paralysis used by industrialized countries Complications paralysis can lead to respiratory arrest and death temporary or permanent deformity