Polio is an infectious disease caused by any one of the three types of polio virus. In the UK, immunisation is automatically offered to everyone as a baby.

What causes polio?

Polio is caused by a ‘picornavirus’. This is one of a group of viruses that live in the intestine. These viruses can be found in the stools of people with polio for up to six weeks after the start of the illness.

Polio mainly affects people who haven't been immunised. Many parts of the world don’t have a problem with polio after immunisation programmes which have wiped out the disease.

In the UK, immunisation is automatically offered to everyone as a baby. Children then have booster doses just before they start school, and then again after they leave. It is young children who are the most at risk from polio, but adults can also have the disease.

What are the signs and symptoms of polio?

Around 95 per cent of polio cases are mild and do not have any symptoms. Otherwise, between three days and three weeks after the infection a child might get a slight fever, sore throat and experience vomiting. This may pass within a few days but sometimes it can be followed by serious illness.

With serious cases of polio, the brain and spinal cord become inflamed with a very bad headache, high temperature, stiff neck and backache. There might even be progressive muscle weakness (paralysis) in one limb. Breathing can be difficult if the respiratory muscles are affected.

In some cases, when the brain stem or upper spinal cord is affected, people can develop a bulbar palsy. This is when the tongue, throat and voice box are paralysed, making it impossible to speak.

How is polio normally diagnosed?

A doctor can tell whether a child has polio by looking at the symptoms. It is also possible to grow (culture) the virus in a laboratory to identify it.

How is polio normally treated?

There is no specific or effective drug treatment for polio. Painkillers are usually enough if the infection is mild.

If the infection is severe, the child will need to go to hospital. In cases of bulbar polio, breathing has to be maintained artificially by machine. The child might need a tracheostomy to open the windpipe and get the air through with an electrical pump.

Many people have physiotherapy to make sure their muscles keep functioning and to help regain movement in any affected limbs.

Can polio be prevented?

Polio is prevented by the ‘five-in-one’ (DTaP/IPV/Hib vaccine), which is given to children. This vaccinates against polio, diphtheria, tetanus, pertussis and Hib infections.

Through vaccination, polio has almost been wiped out in the UK.

What happens next?

Sometimes some of the symptoms of polio reappear in a condition called post-polio syndrome (PPS). It’s thought that 25 to 50 per cent of people who survive polio can have PPS.

It can happen a long time after having polio – sometimes 10 to 40 years later. PPS is not the disease reoccurring but a separate condition that affects people who have recovered from polio.

Last review date:
July 2011