Polio, also known as poliomyelitis, is caused by a highly infectious virus. For most people, polio is a mild illness and causes flu-like symptoms. However, polio can be potentially fatal. A severe case of polio attacks the nerve cells that help the muscles to function and can cause severe muscle paralysis (paralytic polio).
How common is polio?
In the past, polio was very common. It was a frequent cause of death and paralysis all over the world, particularly in young children. The last epidemic in Ireland was over 50 years ago and the last case of polio was recorded in 1984.
Due to the introduction of a polio vaccine the number of polio cases has been dramatically reduced worldwide. Certain areas of the world continue to report polio cases, including.
- Afghanistan, and
There is no cure for polio so it is important to prevent it from occurring. Make sure your child receives all their necessary immunisations.
While polio is essentially a disease of the past, an increasing number of people are developing a poorly understood condition called post-polio syndrome (PPS).
PPS affects approximately 20-66% of people who have had polio. You may develop PPS between 10 and 40 years after your initial illness, with symptoms taking an average of 30 years to develop.
The initial symptoms of PPS include:
- increasing weakness
- stamina problems
You may have difficulty getting around or carrying out everyday tasks and activities.
The cause of PPS is unknown. One theory is that the polio virus may lay dormant (inactive) in your system after the original infection because your immune system has not completely destroyed it. At a later date, the dormant virus may become 'reactivated', although it is not known what triggers this reactivation.
Other theories suggest that PPS is the result of damaged nerve cells that gradually deteriorate over time.
In recent years, PPS has become more common in Ireland, largely due to the high number of polio cases during the 1940s and 1950s. However, as polio is no longer naturally active in Ireland, PPS should become much rarer in the future.
There is currently no cure for PPS, although a range of treatments can help you to manage the symptoms. For more information, see Post Polio Support Group, Ireland.
- Vaccination, or immunisation, is usually given by injection. It makes the body's immune system produce antibodies that will fight off a virus.
- Pain is an unpleasant physical or emotional feeling that your body produces as a warning that it's been damaged.
- Immune system
- The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
In 99% of cases, polio is a mild condition that causes very few symptoms. Some people do not notice any symptoms at all. A mild case of polio usually causes flu-like symptoms, which may include:
- sore throat
- a high temperature (fever) of 38°C (100.4°F) or above
These symptoms usually appear between 3 and 21 days after someone has become infected with the virus.
The paralytic form of polio is very rare. Less than 1% of people are affected by the condition. The first symptom of this form of polio is a fever. Between five and seven days after the onset of the fever, other symptoms will develop, including:
- back and neck stiffness
- increased sensitivity to touch
Paralytic polio can also cause weakness of your muscles because the condition damages the nerve cells in your body. This means that your muscles are no longer able to function normally. Someone with paralytic polio may find that their limbs appear loose and floppy.
Paralytic polio can also affect your:
- ability to see
- ability to hear
- ability to smell
- ability to taste and swallow
- facial muscles,
- heart, and
Usually, the breathing muscles (lungs and diaphragm) are mainly affected. If the breathing muscles become paralysed, your body will be unable to get enough oxygen and a ventilator may be required. See Treatment for more information. Paralytic polio is potentially fatal.
The extent of the paralysis depends on how many nerve cells have been affected. If the cells have been completely destroyed, paralysis is likely to be permanent. If the cells have only been damaged, recovery from paralysis is more likely.
Post-polio syndrome (PPS) can cause a wide range of symptoms, some of which are more common than others. These are explained below.
Common symptoms of PPS
Fatigue is the most common symptom of PPS. Fatigue can take many forms in PPS, 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
Symptoms of fatigue are usually worse in the early afternoon and can often be improved 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 (atrophy) of affected muscles.
Muscle and joint pain
Muscle and joint pain is also common in PPS. Muscle pain is usually experienced as a deep ache in the muscles and/or muscle cramps and spasms.
The pain is often worse after you have used the affected muscles. Therefore, it can be particularly troublesome during the evening after a day's activities.
Joint pain is similar to arthritis, consisting of soreness, stiffness and a reduced range of movement.
As well as the common symptoms of PPS, there are a number of associated symptoms that arise from the combination of fatigue, muscle weakness and muscle and joint pain. These are explained below.
Due to the combination of fatigue, muscle weakness and muscle and joint pain, 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 the symptoms of 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 difficulties 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 require the use of a wheelchair.
Sleep apnoea affects many people with PPS. It is a condition in which the muscles in your throat relax during sleep.
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.
As you need a certain amount of deep sleep for your body and mind to be fully refreshed, having only limited episodes of deep sleep will cause you to feel very tired the next day.
Weakness in the muscles you use for chewing and swallowing may lead to problems swallowing (dysphagia), such as choking or gagging when trying 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.
Usually, swallowing problems are mild and progress very slowly. A speech and language therapist may be able to help.
Sensitivity to cold
Some people with PPS find that one particular part of their body, usually a limb, becomes very sensitive to the effects of cold temperature or a sudden drop in temperature.
Due to this intolerance to cold, you may need to add extra layers of clothing to the affected body part.
Polio is caused by a virus called an enterovirus. This type of virus grows and thrives in the gastrointestinal tract (the system of organs that help digest food, such as the intestines and stomach). After growing in the gastrointestinal tract, an enterovirus often moves on to affect the nervous system.
How is the virus spread?
The polio virus is usually spread through the faeces of someone who is infected with the illness. This is why polio is usually more common in less developed countries that have poor sanitation.
The virus is most easily transmitted when someone has oral contact with infected faeces. This usually happens when a person drinks water that has been contaminated with infected faeces.
Polio can sometimes be spread through contaminated food. In rare cases, it can be transmitted through direct contact with someone who is infected. This is because the virus will be present in the saliva of an infected person, so contact, such as kissing, may spread the infection.
Once the polio virus enters your body, it begins to multiply in your throat and intestines. It then travels to your central nervous system through your blood. In rare cases, as the virus moves along your nervous system, it may damage your nerve cells. This causes paralytic polio (see Symptoms).
How long will someone remain infected?
People infected with the polio virus are most contagious seven to ten days before and after their symptoms appear. However, they can spread the virus for up to six weeks in their faeces.
The exact cause of post-polio syndrome (PPS) is unknown, although there are a number of theories.
One leading theory is that PPS is caused by problems with nerve cells, called motor neurone cells. Motor neurone cells are used by your brain to send signals to your muscles. It is these cells that 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.
It is thought that the enlargement of the motor neurones may weaken them and, over many years, the cells may start to break down. This leads to the symptoms of muscle weakness, muscle wasting and fatigue.
Another theory is that the polio virus (or fragments of the virus) lays dormant in the nervous system for many years. Then, for reasons that are currently unknown, it suddenly becomes reactivated.
The symptoms of PPS could either be caused by the virus itself, or by your immune system mistakenly attacking healthy cells in an attempt to kill the virus.
Polio can normally be diagnosed through the symptoms. This may be more difficult if you have a mild case of the illness.
To confirm a diagnosis of polio, a sample of saliva or stools can be taken and tested for the polio virus in a laboratory. In some cases, a sample of cerebrospinal fluid is taken and tested for the virus. Cerebrospinal fluid is the liquid substance that surrounds and protects the brain and the spinal cord.
There are no definitive tests to confirm a diagnosis of post-polio syndrome (PPS). Your GP will normally make a diagnosis by looking at your medical history and by carrying out a physical examination.
If you have PPS, you will have had a long period without symptoms following the initial attack from the virus (usually between 10 and 40 years). Your GP will ask you when you first noticed your symptoms. The symptoms of PPS usually develop gradually. Therefore, if your symptoms appeared suddenly, they may have been caused by a different condition.
As the symptoms of PPS are similar to those of a number of 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 will need to have a blood test. Someone with PPS will usually have normal blood test results. However, if your blood test result is abnormal, it 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 and/or joints.
If, after these tests, your GP is still unsure whether you have PPS, you may be referred to a hospital consultant. At this stage, you may have some or all of the following tests to rule out other conditions or to confirm the likelihood of PPS:
- 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
- magnetic resonance imaging (MRI), 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 PPS.
There is currently no antiviral medication to treat polio, but there is a vaccine to prevent it (see Prevention).
In the rare situation when someone develops polio, treatment usually focuses on:
- easing pain and discomfort
- speeding up recovery, and
- preventing complications
If you have polio, you will usually be advised to have strict bed rest for a few days, even if it is a mild case of the illness.
Analgesics (painkillers), such as paracetamol, can be prescribed to ease the pain of a headache, sore throat and neck and back stiffness.
If you have constipation, laxatives may be prescribed to help you pass stools (faeces) more easily. You will also be advised to eat a diet that is high in fibre because this will help to soften your stools and make them easier to pass.
If you have severe polio or paralytic polio, you will need to be treated in hospital.
If you are having difficulty breathing because your breathing muscles have been damaged by the virus, you may have to be placed on a ventilator.
A ventilator is an artificial breathing machine that moves air in and out of the lungs. If your breathing muscles are able to repair themselves, you can be removed from the ventilator.
If your muscles have been damaged or paralysed as a result of polio, you will probably be referred for physiotherapy and occupational therapy to improve your mobility and independence.
Physiotherapy uses a range of treatments, such as massage, exercise and hydrotherapy (water massage), to help improve your ability to use the parts of your body that were affected by the virus.
An occupational therapist can provide you with the practical support you need to make everyday tasks and activities easier to manage. The aim of occupational therapy is to get you to live as independently as possible.
Your care team
Post-polio syndrome (PPS) is a complex condition with a wide range of symptoms that can affect many aspects of your life.
You will probably be treated by a combination of different healthcare professionals working together. This type of team is known as a multidisciplinary team (MDT).
Members of your MDT may include:
- a health visitor
- a social worker
- a physiotherapist, who helps people by improving their range of movement and co-ordination
- a speech and language therapist, who can help you with any swallowing difficulties you may have
- an occupational therapist, who helps people to improve the skills needed for performing daily activities, such as washing and dressing
- a mobility specialist, who can provide advice about mobility aids, such as walking sticks and wheelchairs
As there is currently no cure for PPS, treatment focuses on helping you manage your symptoms and improving your quality of life.
An effective way to manage symptoms of fatigue is a type of physical therapy known as 'pacing'.
Pacing involves learning to recognise when to stop what you are doing before you become exhausted.
By always stopping before you are tired, you may be able to accomplish more activities over the space of a day than if you tried to do things without taking a break.
Pacing involves breaking up activities into smaller ones with rests in between.
If you switch between several different jobs or repetitive activities, you will be using different muscles and resting others. If a job cannot be broken up, it may need to be done a completely different way. You may need help from another person or you may realise that the job was not necessary after all.
For example, several smaller trips to a supermarket may be easier than one large shop. If you find that driving to the supermarket and back is tiring, you may consider having home deliveries.
Many people with PPS have a problem adapting to pacing because, when they had polio as a child, they were encouraged to 'use it or lose it'. In other words, they were told to make every effort to use their muscles, even if it caused symptoms of pain and fatigue.
Many years later, they are being told the exact opposite. For some people, this can be difficult to accept. One way of thinking about pacing is 'conserve it and preserve it'. If you make effective and efficient use of your strength and muscle function, they will last longer.
Ideally, pain and fatigue can be reduced with some of the advice above. However, if even the most ordinary daily activities cause pain, various medications are available, from over-the-counter painkillers - such as aspirin, paracetamol or ibuprofen - to stronger anti-inflammatory drugs and opiates.
Over-the-counter (OTC) remedies should not be used on a long-term basis without discussing it with your GP, as they can cause complications, such as stomach ulcers
While it is not usually considered as an initial option, you may want to discuss gabapentin with your GP. Gabapentin is a medication that was originally developed for epilepsy. However, it has also proved useful for people with PPS pain when other types of painkillers have not helped.
Possible side effects of gabapentin include:
- loss of co-ordination
Do not drive if gabapentin makes you drowsy. Do not suddenly stop taking gabapentin as you will experience withdrawal symptoms. These could include:
If you want to stop taking gabapentin, or you no longer need to take it, your GP will arrange for your dose to be gradually reduced over a week. This will ensure that you do not experience any of the above withdrawal symptoms.
Opiates, such as codeine, may cause drowsiness or depressed breathing as well as other side effects, including constipation. Muscle relaxants, such as benzodiazepines, which are sometimes used for muscle cramps, may also cause drowsiness and increased weakness.
It is important to remember that while your pain is being controlled by medication, you may not be aware of the damage that may be caused to your joints by over-activity. It is, therefore, important to stick to your pacing regime even if you do not feel any symptoms of fatigue and pain.
Various mobility aids, such as walking sticks, crutches, ankle braces, callipers, wheelchairs or scooters, may make it possible for you to do many of the things that were becoming difficult or impossible.
Many mobility aids are available free on the NHS. Before contacting your local supplier, it is important to have an idea of what is available. You can get help with this from Disability Living Centres (DLCs).
DLCs provide a permanent exhibition of products and equipment. This gives people an opportunity to see and try products and equipment and get information and advice from professional staff about what might suit them best.
Mobility aids that can benefit people with PPS include:
- braces that can support weakened muscles and joints, as well as improving posture and preventing falls
- canes and waking sticks
- electric scooters
Weight control and healthy eating
Being overweight can put further strain on weakened muscles and will not help your energy levels and overall general health. Losing weight if you need to can help reduce your PPS symptoms.
While regular exercise is a good way of controlling your weight, it may not be possible due to your physical condition.
Following a sensible, healthy eating plan will help you reduce and control your weight and improve your health. It is important to eat a healthy, balanced diet, including foods that provide energy that is released slowly over long periods.
Trying new foods, new food combinations or new ways of cooking to widen the variety of tastes and textures and stimulate the appetite can be an enjoyable way to lose weight and improve your health. If necessary, your GP can refer you to a dietitian.
The following advice makes use of the pacing technique mentioned above.
- Plan your meals in advance.
- Break down cooking tasks into smaller, more manageable ones.
- Set aside more energetic days for food preparation and cook extra amounts to freeze for less energetic days.
- Use cookery books that contain simple, healthy meals that are quick to prepare, such as pasta or salads. Your local library will stock a range of recipe books.
- Some kitchen equipment, such as food processors, microwaves and slow cookers, can help you save time and energy.
- Some utensils are specially designed for people who do not feel strong or have difficulty using their hands.
- Ready meals and tinned and packet foods are useful if you feel too tired to cook a meal from scratch. However, as they are usually high in salt, sugars and fats, low in vitamins and minerals and contain food additives, do not eat them too often.
Coping with the psychological impact of post-polio syndrome
PPS can often have a severe psychological impact. The symptoms of PPS can be distressing and, in addition, developing PPS can often bring back painful childhood memories of living with polio.
It can often feel very cruel that, having struggled to overcome a polio infection during childhood, your life has suddenly been affected by polio again. This can lead to feelings of anxiety, isolation and stress, which can sometimes trigger depression.
If you have been feeling very down during the past month and you no longer take pleasure in the things that you used to enjoy, you may be experiencing depression. If this is the case, contact your GP.
Do not neglect your psychological wellbeing. Aside from the adverse effect on your quality of life, feelings of depression and anxiety can interfere with your treatment.
Most cases of polio are mild and do not cause any complications. Most people with polio make a full recovery. However, for those with paralytic polio, complications are common and the condition can cause lasting damage, particularly to the muscles. Some of the more common complications of paralytic polio are outlined below.
Paralytic polio can cause temporary or permanent muscle paralysis. The extent of the paralysis depends on how many nerve cells have been damaged by the virus.
Children under five years of age are most likely to experience paralysis in one leg. Children aged between 5 and 15 years of age usually have paralysis in either one leg or both legs. Adults are usually the most severely affected as they are more at risk of having paralysis in both legs and both arms.
As polio damages the cells that help control the muscles, it can cause the muscles to become deformed. In particular, the hips, ankles and feet can be affected. These muscle deformities can be painful and affect mobility.
Pulmonary oedema occurs when there is an increase in blood pressure in your lungs' blood vessels. This increase in pressure forces fluid into your lungs and stops them from working properly by preventing them from absorbing oxygen. Polio can affect the breathing muscles and some people will need to be placed on a ventilator to help them breathe (see Treatment).
Aspiration pneumonia occurs when your lungs become inflamed. This type of pneumonia usually develops when you inhale foreign material (usually the contents of your stomach) into your lungs.
People with polio get this type of pneumonia when their swallowing muscles are damaged by the virus. This makes it easier for the stomach contents to enter the lungs.
Myocarditis causes the heart muscle (myocardium) to become inflamed. This can occur when the polio virus attacks the nerve cells in the heart muscle. Myocarditis can cause chest pain, abnormal heart beat (arrhythmia) and, in severe cases, can lead to heart failure.
As paralytic polio can very debilitating, some people may develop depression, particularly if they have experienced paralysis. Muscle paralysis or deformity may affect a person's ability to carry out their job or perform everyday tasks.
It can be very difficult to come to terms with a disability, both physically and mentally. It is important that someone with paralytic polio receives emotional as well as physical support to aid their recovery.
In Ireland, the last case of a natural polio infection occurred in 1984.
Polio no longer exists naturally in Ireland largely due to our immunisation programme.
The most important way to prevent polio is by immunisation with Inactivated (Killed) Polio Vaccine (IPV). The polio vaccine is given to children as part of the 6 in 1 vaccine at 2, 4 and 6 months of age. The 6 in 1 vaccine protects against Diphtheria, Hepatitis B, Hib (haemophilus Influenzae B) Pertussis (Whooping Cough) Polio and Tetanus.
Booster vaccine doses are given at 4-5 years of age (4 in 1 vaccine) which protects against Diphtheria, Pertussis (Whooping Cough), Polio and Tetanus,
If your child requires vaccination, or you are unsure of your child’s vaccination status, contact your GP for advice.
Vaccination before travel
Travelers to some Africa or Asia may need a booster. Contact your GP before travel to see if you should get one.
The Global Polio Eradication Initiative
In 1988, the World Health Organization (WHO) launched the Global Polio Eradication Initiative to help prevent the polio virus on a worldwide scale by encouraging mass vaccination against the illness.
Since the initiative was set up, the number of polio cases worldwide has fallen by 99%. As a result, there are now only four countries where polio remains a serious problem. These are Nigeria, India, Afghanistan and Pakistan.