Poliomyelitis or Polio
what is Poliomyelitis?
Poliomyelitis is an acute infectious disease caused by a group of polio virus. The disease is spread by healthy carriers or diseased person through faeco-oral route and droplet infection through nasopharynx. Poliomyelitis can affect the nerves and leads to partial or full paralysis.
How Poliomyelitis spread?
Poliomyelitis infection spread from healthy carrier or from infected contacts by droplet infection and enters the body through nasopharynx.It is also transmitted through faeco-oral route and enters the body through gastro intestinal tract by contaminated water, food and milk etc.
Cases of polio occur sporadically round the year. Disease occurs in epidemic form in late summer. More than 98% of poliomyelitis illness is asymptomatic i.e. having no symptoms. Only 1 to 2% of cases has symptoms of disease and are called symptomatic poliomyelitis. Disease most frequently affects children under five years but it can also affect young adults too.
People at risk by Poliomyelitis:
Poliomyelitis affects mainly children under five years of age. If children under five years are not immunised against polio, they are at risk.
Distribution and Global case loads of Poliomyelitis:
In the year 1988 more than 125 countries have 3 lacks and 50 thousand of polio cases in epidemic form. In the year 2009 polio cases reduced from 3.5 lacks to 1604 polio cases by the effort of Global Polio Eradication Programme. In 2010 only four countries have poliomyelitis cases in endemic form. These countries are India, Pakistan, Nigeria and Afghanistan.
Incubation period of Poliomyelitis:
Incubation period of disease is the time taken between the infection and beginning of symptoms. In case of poliomyelitis it lasts between 4 to 35 days. Average incubation period is 7 to 14 days.
Types of Poliomyelitis Vaccine:
There are two types of polio vaccines
1. Salk vaccine or inject able polio vaccine and
2. Sabine or oral polio vaccine
How signs and symptoms or clinical features appear in Poliomyelitis:
Once a person is infected by polio virus, viraemia with mild fever, headache, mailase, sore throat and gastrointestinal disturbance occur which lasts for 24 to 48 hours. In majority (98%) of cases this minor illness occurs. This stage of illness is known as Abortive poliomyelitis. It subsides without any complication. In other 1-2% cases major illness of disease occur i.e. after 3 to 7 days of minor illness recurrence of high fever with history of minor illness seen. It is less than 50% cases in epidemic season.
Major illness of poliomyelitis is divided into three stages
• Pre Paralytic Stage
• Paralytic Stage and
• Residual Disability Stage
Pre Paralytic Stage
This stage is characterised by:
• High fever (102 to 104 degree F or 39 to 40 degree C)
• Severe headache
• Neck rigidity
• General discomfort (malaise)
• Throat conjection
• Tender muscles
In some cases above symptoms subside without further development of poliomyelitis in 1 to 2 days and are known as Sub clinical polio or Non paralytic poliomyelitis. It occurs in about 98% of cases. In rest of 1-2% cases above symptoms including fever subsides and paralysis appears.
Paralytic stage : In this stage although fever and other symptoms subside but still muscle tenderness and pain present. Paralysis in poliomyelitis may appear with irregular distribution. It may be patchy or appear at many sites. Complete paralysis spread within 24 hours and persist for several days. By the end of first week muscle power may return and continued for several months
Residual Disability Stage :
Patchy and irregular paralysis of different degree leads to deformity.
Signs of Poliomyelitis:
Signs of poliomyelitis are as follows-
• Flaccid paralysis
• Loss of reflexes
• Atrophy of affected muscles
• Neck rigidity +ve
• Loss of superficial reflexes
• Painful tender affected parts
• Respiratory rate increased
• Cyanosis is a late sign
• Short burst speech
• Alae nasi is widened
• Patient restless and unable to speech
• Involvement of lower cranial nerves impairs swallowing & coughing
• Inability to cough or swallow secretions collect in the pharynx leads to respiratory obstruction (which is a serious emergency & treated soon.)
Complications of Poliomyelitis:
• Paralytic polio after initial recovery
• Skeletal deformities are due to muscles paralysis or paresis, like Equinus foot, Tendons Achilles, Scoliosis, i.e. deformity of spine, Osteoporosis and bone fractures.
• Pulmonary oedema
• Urinary tract infection
• Kidney stones
• Aspiration pneumonia
• Paralytic ileus
• Myocarditis and
Diagnosis of Poliomyelitis:
Diagnosis of polio is made by proper history and physical examination. Diagnosis is confirmed by presence of polio virus in stool, throat swab or cerebro spinal fluid culture.
Prevention of poliomyelitis:
Prevention of poliomyelitis is done by proper hygiene and immunization of children under 5 years of age against poliomyelitis by Polio Vaccine.
Prognosis of Poliomyelitis:
Prognosis in case of Abortive Poliomyelitis infection recovery is 100%.In case of Pre paralytic stage, in few cases symptoms of polio subsides after 1to 2 days without paralysis and muscular atrophy Mortality rate is 2-5% in children and 10-25% in adults. Prognosis of disease is poor in Paralytic polio due to involvement of respiratory muscles and central nervous system.