What is polio?

Poliomyelitis (polio) is a highly infectious disease caused by the poliovirus. It can be preventable via vaccination. Poliovirus invades the nervous system, and can cause total paralysis in a matter of hours. It can strike at any age, but mainly affects children under 3 years old.1

Most people infected with the poliovirus have no signs of illness. Symptomless people can spread the infection to thousands of others before the first case of polio paralysis emerges. When symptoms do occur they can range from a mild illness with fever, to meningitis or paralysis.2

Related: Diphtheria | Tetanus

The following is a summary about the disease. For further details speak to your local pharmacist or GP.

How is polio spread?

‘Wild’ polio infection:

The naturally occurring poliovirus is known as ‘wild virus’. It can be spread via:

  • Faeco-oral route
  • Droplets launched into the air when coughing or sneezing
  • Food or water contaminated with infected poo or droplets2

The virus enters the mouth and travels to the throat and bowels, where it starts to multiply. In some cases, it can also enter the bloodstream and spread to the nervous system.

The virus can be spread by someone with the infection from about a week before any symptoms develop, until several weeks afterwards.

Approximately 95% of infections are mild (flu-like symptoms) or asymptomatic. Infected people who do not show any symptoms can still pass polio on to others.

Polio associated with vaccines:

1. Vaccine-associated paralytic polio (VAPP):

Rarely, the live attenuated vaccine virus in oral polio vaccine (OPV) can cause paralysis – either in the vaccinated child, or in a close contact.3 Due to this, many countries including the UK are now using the inactive (injected) vaccine for this reason.2

2. Vaccine-derived polioviruses (VDPVs):

Additionally, rarely, a strain of poliovirus in oral polio vaccine may genetically change so that it can both cause paralysis and circulate among a population.3

In which countries is polio found?

As a result of routine vaccination programmes, polio has been largely wiped out in most parts of the world.

Areas declared polio-free by the World Health Organization (WHO) include Europe, the Americas, the western Pacific region and, most recently, southeast Asia.

It’s still a significant problem in Afghanistan, Nigeria and Pakistan. There is a potential risk of infection in other parts of Africa and some Middle Eastern countries.4

Further details of countries endemic for wild poliovirus can be found here.5

What are the signs and symptoms of polio?

People with polio who are asymptomatic will fight off the infection.

A small number of people will experience a flu-like illness 3-21 days after infection.1

Symptoms last for approximately a week and may include:

  • Fever
  • Sore throat
  • Headache
  • Stomach pain
  • Aching muscles
  • Feeling and being sick

In less than 1% of cases, the polio virus attacks the nerves in the spine and base of the brain. This can cause paralysis, usually in the legs, that develops over hours or days. The paralysis isn’t usually permanent, and movement will often slowly return over the next few weeks and months. Some people are left with persistent problems. If the breathing muscles are affected, it can be life threatening.

What are the complications of polio?

Although polio often passes quickly without causing any other problems, it can sometimes lead to persistent or lifelong difficulties. About 1 in every 200 people with the infection will have some degree of permanent paralysis, and others may be left with problems that require long-term treatment and support.

These can include:

  • Muscle weakness
  • Shrinking of the muscles (atrophy)
  • Tight joints (contractures)
  • Deformities, such as twisted feet or legs

There’s also a chance that someone who’s had polio in the past will develop similar symptoms again, or worsening of their existing symptoms, many decades later. This is known as post-polio syndrome.

 Complications of paralytic polio

Early complications:

  • Paralysis, often of one leg or paraplegia
  • Pneumonia
  • Urinary tract infection

Late complications:

  • Osteoporosis
  • Post-polio syndrome – includes symptoms such as functional deterioration, fatigue and respiratory problems6

How is polio treated?

There is currently no cure for polio. Treatment focuses on supporting bodily functions and reducing the risk of long-term problems.

Management of acute paralytic polio includes:

  • Strict bed rest to prevent extension of the paralysis
  • Supportive care such as pain relief
  • Prevent deformity by stretching exercises and splinting of affected limbs
  • Intensive physiotherapy and occupational therapy6

What advice is there for those travelling to high risk countries?

An effective vaccination against polio is available. In addition to vaccination, travellers should ensure good personal hygiene and follow advice on prevention of food and water-borne diseases.

When to consider vaccination

Polio vaccine is recommended for:

  • All individuals, from 2 months of age as part of the UK routine immunisation schedule
  • Travellers to areas or countries where there are recent reports of wild polio and their last dose of polio vaccine was given 10 or more years ago
  • Individuals at risk of exposure to polio through their work, e.g. certain healthcare workers and microbiology laboratory staff2


The polio vaccine is now only given as part of combined products:

  • Diphtheria/tetanus/acellular pertussis/inactivated polio vaccine/Haemophilus influenzaetype b (DTaP/IPV/Hib)
  • Diphtheria/tetanus/acellular pertussis/inactivated polio vaccine (DTaP/IPV)
  • Tetanus/diphtheria/inactivated polio vaccine (Td/IPV)7

These vaccines are inactivated, do not contain live organisms and cannot cause the diseases against which they protect. It can therefore be given safely to people with immunosuppression (including those with HIV) and to pregnant and breast-feeding women.

Childhood vaccination programme:                 

The polio vaccination is offered as part of the NHS routine childhood vaccination programme. It’s given by injection in 5 separate doses. These are normally given at:

If planning to travel to a polio-affected country, travellers should get vaccinated if they have not been fully vaccinated before. If it has been more than 10 years since the last dose, a booster dose is required.


This information is taken from trusted third party websites, NaTHNaC (Travel Health Pro) and EMIS (Patient info) and use of all information has been licenced under the Open Government. Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/

Although the materials are being used/replicated under the provisions of the Open Government Licence this in no way represents endorsement of Traveljab.co.uk by NaTHNaC, Emis, Public Health England, the NHS or the Department of Health and Social Care.

  1. UK: Polio: guidance, data and analysis
  2. Travel Health Pro: Poliomyelitis factsheet
  3. Polio: Global Eradication Initiative: Vaccine-associated paralytic polio (VAPP) and vaccine-derived poliovirus (VDPV)
  4. NHS: Polio
  5. World Health Organization (WHO): Polio-infected countries
  6. Patient.info: Polio and Polio Vaccination
  7. The Green Book: Chapter 16 – Poliomyelitis
  8. NHS: 6-in-1 vaccine
  9. NHS: 4-in-1 pre-school booster
  10. NHS: 3-in-1 teenage booster