Poliomyelitis

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Introduction

  • An acute infectious disease of humans (particularly children) caused by any of three serotypes of poliovirus P1, P2, and P3
  • Immunity to one serotype does not confer immunity to others
  • Occurs in many regions of the developing world
  • There was an increase in global cases as a result of an epidemic in India
  • In 2015, Nigeria was declared a polio free country.

Pathogenesis

  • Entry into mouth (via faecally-contaminated food/water)
  • Replication in pharynx, gastrointestinal tract, local lymphatics
  • Haematologic spread to lymphatics and central nervous system
  • Viral spread along nerve fibres
  • Destruction of motor neurons

Clinical features

Incubation period: 6 - 20 days, with a range of 3 – 35 days

Asymptomatic infection: 95%

Minor non-specific symptoms: 4 - 8%

Symptoms occur in less than 2 %

  • Slight fever
  • Headache
  • Malaise
  • Sore throat
  • Vomiting

Non-paralytic polio (1-2%)

Symptoms last 1- 2 weeks

  • Moderate fever
  • Headache
  • Vomiting
  • Diarrhoea
  • Fatigue
  • Irritability
  • Pain or stiffness of the back, arms, legs, abdomen
  • Muscle tenderness and spasms in any part of the body
  • Neck pain and stiffness
  • Skin rash

Paralytic polio

3 types depending on the level of involvement

  • Spinal polio: 79%
  • Bulbar polio: 2%
  • Bulbospinal: polio 19%
  • Fever 5 - 7 days before other symptoms
    • Headache
    • Stiff neck and back
    • Asymmetric muscle weakness
    • Rapid onset
    • Progresses to paralysis
    • Location of paralysis depends on region affected
    • Abnormal sensation
    • Hyperaesthesia
    • Difficulty in initiating micturition
    • Constipation and Bloated abdomen
    • Dyspnoea, Dysphagia and Drooling
    • Muscle spasms
    • Irritability
    • Positive Babinski's sign

Complications

  • Multiple intestinal erosions
  • Acute gastric dilatation
  • Hypertension
  • Hypercalcaemia
  • Nephrocalcinosis
  • Vascular lesions
  • Myocarditis
  • Pulmonary oedema and Pulmonary embolism
  • Paralysis muscles of respiration and swallowing which can be fatal

Differential diagnoses

  • Guillain- Barre syndrome
  • Lead toxicity
  • Cranial nerve Herpes zoster
  • Post-diphtheric neuropathy
  • Viral encephalitis
  • Rabies
  • Tetanus

Investigations

Viral isolation from stool, pharynx or cerebrospinal fluid

  • Fingerprinting genomic sequencing to determine if it is the wild type or vaccine type
  • Serology: a fourfold rise in antibody may be demonstrated
  • Cerebrospinal fluid examination:
    • Raised white cell count, 10 - 200 cells/mm3(primarily lymphocytes)
    • Mild increase in protein: 40 - 50 mg/mL

Treatment goals

  • Allay fear
  • Minimize ensuing skeletal deformities
  • Anticipate and treat complications
  • Prepare the child and family for a prolonged management of permanent disability if it seems likely

Non-drug treatment

  • Bed rest
  • Avoidance of exertion and application of hot packs
  • Lying on a firm bed and hospitalization for those with paralytic disease
  • Suitable body alignment to avoid excessive skeletal deformity
  • Active and passive motions as soon as pain disappears
  • Manual compression of the bladder
  • Adequate dietary and fluid intake
  • Review by orthopaedist and psychiatrist
  • Gravity drainage of accumulated secretions
  • Tracheostomy in case of vocal cord paralysis

Drug treatment

  • Bethanicol 5 - 10 mg orally or 2.5 - 5 mg subcutaneously for bladder paralysis
  • Analgesics
    • Avoid opiates if there is impairment of ventilation
  • Treat urinary tract infection with appropriate antibiotics

Prevention

Hygienic practices

  • To prevent / limit contamination of food and water by the virus

Vaccination

  • The only effective method of prevention

Oral Polio Vaccine

  • Given at: Birth, 6 weeks, 10 weeks, 14 weeks
  • Highly effective
  • 50% immune after 1 dose
  • >95% immune after 3 doses
  • Confers herd immunity
  • Immunity probably life long
  • Limits spread of wild polio virus

Inactivated Polio Vaccine:

  • Given at: 2 months, 4 months, 12 months
  • Highly effective
  • >90% immune after 2 doses
  • >99% immune after 3 doses
  • Duration of immunity not known with certainty

Notable adverse drug reactions, contraindications, and caution

Oral polio vaccine:

  • Paralytic poliomyelitis
  • Should not be administered to persons who are immunocompromised (it is a live vaccine)

Contra indicated in :

  • Persons with history of severe allergic reaction to a vaccine component or following prior dose
  • Moderate or severe acute illness

Inactivated vaccine may be used in immune compromised persons

  • It may (rarely) cause local reactions