While polio is essentially a disease of the past, an increasing number of people who have had polio are developing a condition called post-polio syndrome (PPS).
PPS is a poorly understood condition that can cause a variety of symptoms, including pain, muscle weakness and fatigue.
Polio was very common in the past. It affected children worldwide, causing paralysis and death. In the UK, there was a widespread outbreak of polio during the 1940s and early 1950s.
Since routine polio vaccination was introduced in 1956, the number of polio cases has significantly reduced. The last case of natural polio infection acquired in the UK was in 1984.
Since then, about 40 cases of polio have been reported in the UK, but these were thought to have been acquired abroad or occurred as a very rare side effect of the attenuated polio vaccine (containing the live virus) that was routinely used up until 2004.
Pakistan, India, Afghanistan and Nigeria are the four countries where polio remains the highest risk. However, outbreaks of polio in other countries do sometimes occur and the condition can be spread to people who aren't protected (see below for vaccination advice for travellers).
There's no cure for polio so it's important to take preventative measures by making sure your child receives all their necessary vaccinations.
Post-polio syndrome (PPS)
It's estimated that there are around 120,000 people living in the UK who survived polio when they were younger. Some of these have, or will, develop a condition called post-polio syndrome (PPS).
Only people who've had polio can develop PPS, but it's not known exactly how many polio survivors are affected. Estimates vary from as low as 25% of those who have had polio to as high as 80%.
PPS takes decades to develop after the initial polio infection, taking an average of 30 years for symptoms to become noticeable.
The symptoms of PPS usually develop gradually and can include:
increasing muscle weakness
muscle and joint pain
breathing or sleeping problems
sensitivity to the cold
Although PPS is rarely life threatening, it can greatly interfere with everyday life, making it difficult to get around or carry out some tasks and activities.
What causes post-polio syndrome?
The exact cause of PPS is unknown but the leading theory is that it's the result of the gradual deterioration of nerve cells in the spinal cord (called motor neurones) that were damaged by the polio virus. This would also explain why PPS can take years to appear.
PPS isn't contagious, and the theory that the polio virus may lay dormant in your system after the original infection, causing PPS when reactivated, has been disproven.
In recent years, PPS has become more common in the UK, largely because of the high number of polio cases during the 1940s and 1950s. However, as polio is no longer naturally active in the UK, PPS should become less common in the future.
How post-polio syndrome is treated
Although there's currently no cure for PPS, a range of treatments and support is available to help manage the symptoms and improve quality of life.
Some of the ways that symptoms of PPS may be managed include:
physical therapy known as "pacing" - to help recognise and manage fatigue
mobility aids -such as walking sticks or scooters
weight control and healthy eating -to avoid putting unnecessary strain on muscles and joints
painkilling medication - to help relieve muscle or joint pain
discussing the psychological impact - for example, with your GP, on an online forum, or in a local support group
Since the introduction of a vaccine in the early 1960s, polio no longer exists naturally in the UK. The vaccine is now part of the childhood vaccination programme. It's prevented by a series of five doses:
babies are offered the polio vaccination as part of the 5-in-1 vaccine at two, three and four months of age
this is followed by a booster dose as part of the 4-in-1 pre-school booster vaccine given to children aged three years and four months or soon after
the fifth and final dose of the polio vaccine is given to children when they are 13-18 years of age as part of the 3-in-1 teenage booster
Advice for travellers
Although there's a very low risk of getting polio in the UK, the condition is still a problem in some countries, particularly in India, Pakistan, Afghanistan and Nigeria.
The NaTHNaC website has more information about other countries where cases of polio have been reported since 2007.
If you're travelling to a country where polio (and diphtheria and tetanus) are widespread, you need to make sure you're fully protected against these conditions. Your GP or practice nurse will be able to check your vaccination history.
After receiving a primary course of the polio vaccine, it's recommended that you should have a booster every 10 years if you're travelling to a high risk area.
In the UK, Revaxis is the brand name of the booster vaccine for polio. It's given as an injection into a muscle, usually in the shoulder. You may experience some slight pain and swelling at the site of the injection for a short time afterwards.
Although this type of vaccine doesn't have adverse effects on the development of an unborn baby, Revaxis isn't routinely recommended for use in pregnant women.
Help and support
The British Polio Fellowship is a leading charity for people affected by polio and post-polio syndrome. It provides a range of useful resources, information and services.
Contact the telephone helpline on 0800 018 0586, or visit the British Polio Fellowship website.
Symptoms of post-polio syndrome
Post-polio syndrome (PPS) can cause a wide range of symptoms that can have a serious effect on everyday life.
Common symptoms of PPS
Fatigue is the most common symptom of PPS. It can take many forms in people with the condition, including:
muscle fatigue – where your muscles feel very tired and heavy, particularly after physical activity
general fatigue – where you feel an overwhelming sense of physical exhaustion, as if you have not slept for days
mental fatigue – where you find it increasingly difficult to concentrate, have problems remembering things and make mistakes that you would not usually make
The fatigue experienced by people with PPS is usually worse in the early afternoon and improves with rest or brief naps.
Increasing muscle weakness is another common symptom of PPS. It can be easy to confuse muscle weakness with muscle fatigue, but they are different.
Muscle weakness means that you are increasingly unable to use affected muscles, whether you feel fatigued or not. Weakness can occur in muscles that were previously affected by an active polio infection, as well as in muscles that were not previously affected.
There may also be associated shrinking of affected muscles, known as atrophy.
Muscle and joint pain
Muscle and joint pain are also common in PPS. Muscle pain is usually felt as a deep ache in the muscles or muscle cramps and spasms.
The pain is often worse after you have used the affected muscles. It can be particularly troublesome during the evening after a day's activities.
Joint pain is similar to arthritis and consists of soreness, stiffness and a reduced range of movement.
As well as the common symptoms of PPS, several associated symptoms can arise from the combination of fatigue, muscle weakness and muscle and joint pain.
Because of the common symptoms mentioned above, most people with PPS become less physically active than they used to be.
This can often lead to weight gain and, in some cases, obesity. This in turn can make any fatigue, muscle weakness and pain worse.
As well as weight gain, the combination of fatigue, weakness and pain can lead to walking difficulties and increasing difficulty with mobility.
Many people with PPS will require a walking aid such as crutches or a cane at some stage, and some people may eventually need to use a wheelchair.
Sleep apnoea affects many people with PPS. It is a condition in which the muscles in your throat relax during sleep, which can lead to problems sleeping.
Once the muscles relax, the airway in your throat can narrow or become totally blocked. This interrupts the oxygen supply to your body, which triggers your brain to pull you out of deep sleep so that your airway can be reopened and you can breathe normally.
Weakness in the muscles you use for chewing and swallowing may lead to problems swallowing (dysphagia), such as choking or gagging when you try to swallow.
You may experience changes in your voice and speech, such as hoarseness, low volume or a nasal-sounding voice, particularly after you have been speaking for a while or when you are tired.
Swallowing problems are usually mild and progress very slowly. A speech and language therapist may be able to help.
Sensitivity to cold
Some people with PPS find that they become very sensitive to cold temperatures or a sudden drop in temperature as a result of poor blood supply.
Because of this intolerance to cold, people with PPS may need to wear extra layers of clothing to try to stay comfortable.
Causes of post-polio syndrome
The exact cause of post-polio syndrome (PPS) is unknown.
The main theory is that it may be caused by the gradual deterioration of nerve cells in the spinal cord (motor neurones), which were damaged by the polio virus during a previous infection.
Motor neurone cells are used by your brain to send signals to your muscles. These cells are targeted by the polio virus.
A polio infection can damage motor neurone cells, leading to a shortage of motor neurones. To compensate for this shortage, the body will enlarge the remaining motor neurones, leading to a recovery of movement in the affected limbs.
It is thought that excessive prolonged use of these enlarged motor neurones may weaken them and the cells may start to break down over the course of many years. This is thought to lead to the muscle weakness, muscle wasting and fatigue associated with PPS.
This theory would also explain why PPS can take years to appear, and why it often has slow and progressive symptoms with periods where normal activity is possible.
Although PPS can only develop in people who have been infected with polio in the past, PPS itself is not contagious. A theory that the polio virus may lie dormant in your body after the original infection, causing PPS when it becomes reactivated at a later stage, has been disproven.
Diagnosing post-polio syndrome
It can be difficult to diagnose post-polio syndrome (PPS) because there are no tests to definitively confirm a diagnosis, and PPS may initially be mistaken for other conditions.
Your GP may suspect PPS based on your medical history and the results of a physical examination. For example, PPS may be suspected if you know you have had polio in the past and you've had a long period without symptoms (usually at least 15 years) after the initial infection.
Your GP will also ask you when you first noticed your symptoms. The symptoms of PPS usually develop gradually, so if your symptoms developed suddenly, they may be the result of a different condition.
As the symptoms of PPS are similar to those of several other conditions, such as arthritis, your GP will try to rule out any other possible causes of your illness. You may have to undergo a series of tests or procedures, depending on what your GP suspects could be causing your illness.
For example, you may have a blood test. Someone with PPS will usually have normal blood test results, but an abnormal result is a strong indication that your symptoms are being caused by a different condition.
You may also have X-rays of your chest and spine or joints.
Referral to a specialist
If your GP is still unsure whether you have PPS after these tests, you may be referred to a hospital consultant for further testing.
Tests you may have to rule out other conditions, or to confirm the likelihood of PPS, include:
electromyography (EMG) tests to determine whether polio has damaged your nerves and muscles (an EMG measures the electrical activity in your muscles and nerves)
sleep studies if you are having problems sleeping or are feeling unusually tired
tests to check your heart rate and function
a magnetic resonance imaging (MRI) scan, a type of imaging scan that can look inside your spine
lung function tests to measure how well you can breathe in and out
tests to investigate swallowing problems
It is possible to have PPS as well as other conditions, so not every health problem or symptom you experience may be related to the condition.
Post polio syndrome