Poliovirus

Snapshot

A 3-year-old girl presents to a local hospital in rural Asia for sudden-onset weakness of the lower extremities over the past 2 days. Her parents report that it seems to affect the right leg more. She has not had any immunizations due to lack of access to hospitals. On physical exam, there is notable muscular atrophy of the right leg and absent reflexes on the right. Reflexes are weak on the left side. Sensation is normal bilaterally.

Introduction

Classification
- poliovirus
  - a non-enveloped single-stranded (+) RNA virus
  - a picornavirus and enterovirus
- transmission
  - fecal-oral
Epidemiology
- incidence
  - endemic in areas of Asia and Africa
- demographics
  - affects children
Pathogenesis
- replicates in oropharynx and small intestines and spreads to the central nervous system via bloodstream
- destroys the anterior horn of the spinal cord, causing lower motor neuron cell death
Associated conditions
- poliomyelitis
- meningitis
Prevention
- vaccines
  - live attenuated oral polio vaccine (OPV)
    - developed by Sabin
    - may be associated with vaccine-associated paralytic poliomyelitis
    - no longer offered
  - inactivated polio vaccine (IPV)
    - developed by Jonas Salk
    - 4 doses for infants 2 months to 4-6 years
Prognosis
- disease starts with preceding aseptic meningitis and progresses to flaccid paralysis
two-thirds of patients do not recover their strength

Presentation

Studies

Differential

Werdnig-Hoffmann disease
- distinguishing factor
  - both affect the anterior horns of the spinal cord but Werdnig-Hoffmann presents with symmetric weakness
Guillain-Barre syndrome
- distinguishing factor
symmetric weakness

Treatment

Management approach
- mainstay of treatment is supportive care
- management is focused on vaccine and prevention
Conservative
- physical therapy and occupational therapy
  - indication
    - all patients
- respiratory support
  - indication
disease progression to respiratory system

Complications