POLIOMYELITIS is an acute infectious disease that may result in severe physical handicap (paralysis). It has probably been recognized for centuries but first appeared in a medical textbook “disease of children” by Michael Underwood in the late eighteen century. The causative organism was discovered by Landsteiner in 1908. The virus is excreted in the faeces of affected person and is acquired through the mouth (faeces oral route) by faecal contamination of water, food and by direct handling.
Who is affected?
It is worldwide in distribution. In Nigeria, like in other developing countries, it is endemic (transmitted throughout the year) and affects children usually below 5 years of age whereas in the developed countries, it tends to occur in epidemics (occasional out-breaks) and can affect older children and young adult as well, the reason for this difference is that in the developing countries, the level of personal and environmental hygiene is so low that almost every child has come in contact with the virus by the age of two years. The majority of such contact would develop into mild infection with resultant immunity (protection against subsequent infection) while only a small fraction develop paralysis.
In the developed countries, on the other hand, the intensity of transmission is at such low level that a lot of children and young adults never come in contact with the virus hence remain susceptible to infection during the occasional outbreak unless they have previously been vaccinated.
Signs and symptoms
The majority (90%) of those infected by the polio virus have no recognizable illness at all. Almost all the other patients have non-paralytic illness, with symptoms as fever, malaise, headache, sore throat, vomiting, diarrhoea, neck and back stiffness and pain. Only about one in a thousand patients go on to develop muscle pain, weakness and inability to work. The legs are more commonly affected but other parts of the body including the arm, trunk, and chest can be affected. Involvement of the muscle of the chest would lead to breathing difficulty. A few patients with more severe involvement may develop difficult in swallowing and speech problem.
Patient with non-paralytic illness recover completely while 50per cent of those with paralysis also recover completely usually within six months. Another 25 per cent recovers partially, while the others suffer permanent damage and over time the limbs become short, thin and deformed.
No child should have polio since it can be prevented by immunization. In fact, Polio has been almost completely eradicated in the developed countries through this means. In Nigeria, oral polio vaccine is given from about the age of two months at the monthly interval from three months. It is given at same time as the vaccine against tetanus, diphtheria and whopping cough (triple antigen).
The treatment of polio is supportive as no drug can modify the severity of the illness. Mild cases can be managed at home or in the health centre and the treatment consists of bed rest and drugs for fever and pain. More serious cases need to be referred to specialist hospitals especially if there is respiratory involvement.