What are the symptoms of polio?

Symptoms of Polio

Most poliovirus infections are asymptomatic, but when symptoms occur, they typically manifest in two phases: an initial nonspecific febrile illness followed by aseptic meningitis or paralytic disease in a small percentage of cases. 1

Initial Phase Symptoms

• Nonspecific febrile illness (first phase) 1
• Fever 1
• Sore throat 2
• Headache 2
• Upper body stiffness 2

Paralytic Polio Symptoms

Paralytic polio occurs in approximately 0.1-1% of all poliovirus infections (ratio of inapparent infection to paralytic disease ranges from 100:1 to 1,000:1) 1. Symptoms include:

• Rapid progression to maximum paralysis (2-4 days) 1
• Fever and muscle pain during progression 1
• Asymmetric spinal paralysis, more severe proximally than distally 1
• Absent or diminished deep tendon reflexes 1
• Bulbar paralysis affecting:
  • Respiration 1
  • Swallowing 1

Types of Paralytic Polio

Depending on the sites affected, paralytic polio can be classified as:

• Spinal (affecting limbs) 1
• Bulbar (affecting brain stem) 1
• Spino-bulbar (combination) 1

Post-Polio Syndrome

After 30-40 years, 25-40% of persons who contracted paralytic polio during childhood may experience post-polio syndrome with the following symptoms 1:

• Muscle pain 1, 3
• Exacerbation of existing weakness 1, 3
• Development of new weakness or paralysis 1, 3
• Joint pain 3
• Generalized fatigue 3
• Cold intolerance 3
• Dysphagia (difficulty swallowing) 3
• Dysphonia (voice problems) 3
• Respiratory difficulties 3

Risk factors for post-polio syndrome include:

• Longer time since acute poliovirus infection 1
• Permanent residual impairment after recovery 1
• Female gender 1

Important Clinical Considerations

• Paralytic polio is fatal in 2-10% of cases 1
• After the acute episode, many patients recover at least some muscle function 1
• Prognosis for recovery can usually be established within 6 months after onset of paralytic manifestations 1
• Even "nonparalytic polio" can cause neuronal lesions in the brain and spinal cord 4
• Intramuscular injections during poliovirus infection can increase the risk of paralytic disease (provocation poliomyelitis) 5

Disease Progression Timeline

• Incubation period: First paralytic manifestations usually occur 7-21 days from initial infection (range: 4-30 days) 1
• Period of communicability: Begins after virus replication and continues until termination of viral excretion, usually 4-6 weeks after infection 1