Infectious Disease: Polio

Question 1

Defintion

Answer 1

Enterovirus disease which spreads to the nervous system causing nerve injury

Question 2

Epidemiology

Answer 2

Children under 5 (majority under 36 months)
Unimmunised

Question 3

Aetiology

Answer 3

Poliovirus (RNA enterovirus)

Question 4

Pathophysiology

Answer 4

Poliovirus is transmitted via the faecal-oral route, particularly in low-hygiene settings.
There is no non-human reservoir. The incubation period varies from 3 days to 30 days, and the virus can be excreted from the gastrointestinal tract for up to 6 weeks.

The virus replicates in the nasopharynx and GI tract and may spread via the bloodstream to the lymph nodes and, rarely, to the central nervous system, where it affects the motor neurons in the anterior horn and brainstem. It is the destruction of motor neurons that leads to the development of acute flaccid paralysis (AFP).

Question 5

Symptoms

Answer 5

Polio MC asymptomatic
Paralytic disease (1%)
● Fever
● Decreased tone and moto function of affected limb
● Decreased tendon reflexes of affected limbs
● Intense muscle pain from spasms and weakness
● Paralysis
● Asymetic
● Affects larger proximal muscles
Infants
● Acute flaccid paralysis (floppy baby syndrome)
● If diaphragm motor nerves are affected: difficulty breathing + death

Question 6

Diagnosis

Answer 6

FBC + U+E
Virus culture from stools, CSF, or pharynx
Lumbar puncture: CSF analysis
Serum antibodies to poliovirus

Question 7

Treatment

Answer 7

● Notify Public health
● Supportive care with rehydration + neurological monitoring
● +/- physiotherapy and mobilisation if AFP
● Ventilation if trouble breathing

● Vaccine- Routine immunization with the polio vaccine is crucial to prevent polio infection and the spread of the disease

Question 8

Complications

Answer 8

AFP
post-poliomyelitis syndrome (PPS)

Question 9

Risk factors

Answer 9

Lack of vaccination,
Poor sanitation,
Areas of endemic infection