Poliomyelitis

Key Features

Essentials of Diagnosis

• Incubation period 7–14 days after exposure

• Headache, stiff neck, fever, vomiting, sore throat

• Lower motor neuron lesion (flaccid paralysis) with decreased deep tendon reflexes and muscle wasting; sensation intact

General Considerations

• Poliomyelitis virus, an enterovirus, is highly contagious through fecal-oral route, especially during the first week of infection

• There are three wild poliovirus serotypes, however, only wild poliovirus type 1 has remained endemic since 2012

• Pakistan, Afghanistan, and Nigeria remain the only countries with endemic poliovirus transmission since 2014

• In 2019, there were 29 cases of wild type polio in Afghanistan and 146 in Pakistan

• In 2020, there have been 2 cases of wild type polio in Afghanistan and 21 cases in Pakistan

• In 2019, there were 354 vaccine-derived polio cases, derived mostly from type 2 attenuated live oral poliovirus vaccine (OPV), reported in 17 countries

• In 2020, there have been 18 cases of vaccine-derived polio reported in 7 countries

• Cases of acute flaccid myelitis (formerly acute flaccid paralysis) resembling polio but not due to poliomyelitis virus are being reported

Clinical Findings

Symptoms and Signs

• At least 95% of infections are asymptomatic

• Patients who become symptomatic can present with abortive poliomyelitis, nonparalytic poliomyelitis, or paralytic poliomyelitis

  • Abortive poliomyelitis: minor illness with nonspecific symptoms, fever, headache, vomiting, diarrhea, constipation, and sore throat lasting 2–3 days

  • Nonparalytic poliomyelitis: In addition to the above symptoms, signs of meningeal irritation and muscle spasm occur in the absence of frank paralysis

  • Paralytic poliomyelitis: present during the febrile period over 2–3 days, is a flaccid asymmetric paralysis affecting mostly the proximal muscles of the lower extremities

    • Sensory loss is very rare

    • Can be divided into two forms that may coexist: (1) spinal poliomyelitis, involving the muscles innervated by the spinal nerves; and (2) bulbar poliomyelitis, involving the muscles supplied by the cranial nerves (especially nerves IX and X) and of the respiratory and vasomotor centers

• Post-polio syndrome

  • Constellation of symptoms that affect polio survivors and is not infectious

  • The syndrome presents with signs of chronic and new denervation

  • The most frequent symptoms are progressive muscle limbs paresis with muscle atrophy, with fasciculations and fibrillation during rest activity

• Acute flaccid myelitis

  • There is no evidence of poliomyelitis infection

  • Enteroviruses are isolated in some of these cases

Differential Diagnosis

• Acute inflammatory polyneuritis (Guillain-Barré syndrome)

• Japanese encephalitis virus infection

• West Nile virus infection

• Tick paralysis

• Acute flaccid myelitis

Diagnosis

• The virus may be recovered from throat washings (early) and stools (early and late)

• PCR of washings, stool, or cerebrospinal fluid can also facilitate diagnosis

• Cerebrospinal findings

  • Normal or slightly increased pressure and protein

  • Glucose is not decreased

  • White blood cells ...