Poliomyelitis

Introduction

Poliomyelitis is 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
It occurs in many regions of the developing countries.
The global polio eradication initiative was launched in 1988. In 15 years, the number of cases had fallen by 99% and the number of infected countries reduced from 125 to 7.

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

  1. Spinal polio: 79%
  2. Bulbar polio: 2%
  3. Bulbospinal: polio 19%

 

  • Fever 5-7 days before other symptoms
  • Headache
  • Stiff neck and back
  • Assymmetric muscle weakness
  • Rapid onset
  • Progresses to paralysis

Location of paralysis depends on region affected

  • Abnormal sensation
  • Hyperaesthesia
  • Difficulty in initiating micturition
  • Constipation
  • Bloated abdomen
  • Dysphagia
  • Muscle spasms
  • Drooling
  • Dyspnoea
  • Irritability
  • Positive Babinski’s sign

Complications

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

Differential diagnoses

  • Guillain- Barre syndrome
  • Lead toxicity
  • Cranial nerve Herpes zoster
  • Post-diphtheric neuropathy
  • Arthropod borne viral encephalitis
  • Rabies
  • Tetanus
  • Botulism
  • Encephalomyelitis: demyelinating type
  • Neoplasms in and around the spinal cord
  • Familial periodic paralysis
  • Myasthenia gravis
  • Acute porphyrias
  • Hysteria and malingering
  • Conditions causing pseudoparalysis
  • Unrecognized trauma
  • Acute osteomyelitis
  • Transient toxic synovitis
  • Congenital syphilis: pseudoparalysis of Parrot
  • Acute rheumatic fever
  • Scurvy

Investigations

  • Viral isolation from stool, pharynx or cerebrospinal fluid

If the virus is isolated from a person with acute paralysis, it must be tested further,
using 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 objectives

  • 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
  • Application of hot packs
  • Lying on a firm bed
  • 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,caution and contraindications

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