Polio is an infectious virus that can attack the nervous system causing permanent paralysis and, in some cases, death.

Victims of the disease can suffer a range of conditions. In many cases flu-like symptoms such as nausea, vomiting, sore throat and headache are the only symptoms – for many, those contracting the disease may not realise they have it.

However, in around 1 in 20 cases, the virus will get into the nervous system. The patient will exhibit symptoms such as a high fever, stiff neck, back and muscle pain and headache - symptoms normally associated with an attack of meningitis (inflammation of the lining around the brain and spinal cord) or encephalitis (inflammation of the brain tissue).

In around 1 in 50 cases, paralytic polio is contracted. The Polio virus attacks the body's motor neurons resulting in weakness, muscle cramps and muscle pain. Such an attack can leave the person with a slight paralysis or a permanent disability. Sometimes the person may appear to have made a full recovery.

If the brain stem is affected by a polio infection then breathing, swallowing and cardiovascular problems can occur. This is known as bulbar polio.

The Polio virus is spread from person-to-person by infected saliva, mucus or faeces. Anyone with the disease remains contagious for many weeks, so whole communities are at risk if one person of the group is infected.

Thanks to a global effort to eradicate the disease, polio cases have decreased from over 350,000 cases globally in 1988 to around 2,000 reported cases globally by 2006.

Though it is estimated that around 120,000 people in the UK have had the disease, there are now no new cases of polio here thanks to continuing polio vaccination.