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Polio (poliomyelitis) is an acute viral illness that occurs in the gastrointestinal tract and can cause lifelong paralysis, and death. Polio mainly affects children under 5 years of age. Wild-type Polio has been mostly eradicated worldwide due to vaccination programmes, but remains endemic in Afghanistan, Pakistan and Nigeria[40]. There have been no confirmed cases of indigenous wild type polio reported in England and Wales since 1984[43].

How is it contracted?
It is spread mainly mainly by ingesting food or water contaminated with faeces in areas where sanitation and personal hygiene are poor. Virus particles are excreted in the faeces for several weeks following initial infection. The disease is highly contagious and in endemic areas, can infect virtually the entire human population. Peak transmission is in summer and autumn in temperate climates, but this is less pronounced in tropical areas.

Signs and symptoms
The polio virus usually has an incubation period of 3 to 21 days [42], and spreads through the bloodstream where it can infect the central nervous system causing serious problems.  The majority of cases cause only minor symptoms including: sore throat, fever, nausea, vomiting, abdominal pain, constipation, and diarrhoea.  Around 1% to 2% of cases develop aseptic meningitis, an inflammation of the lining of the brain, which is characterised by stiffness of the neck, back, and/or legs which usually resolves [42]. In less than 1% of all polio infections, the virus infects the spinal cord [41] and results in acute flaccid paralysis of either single or multiple limbs and the respiratory muscles, which can lead to suffocation. 

The majority of patients recover completely and often in less than a week. In those who develop only meningitis, the symptoms can be expected to persist for two to ten days, followed by complete recovery. 1 in 200 infections results in irreversible paralysis, usually of the legs [40]. About 50% of people with paralytic polio recover from the acute paralytic stage of the disease without long term paralysis, 25% have mild permanent disability and 25% have permanent severe paralysis requiring long-term rehabilitation [42]. Without respiratory support, 5–10% of patients with paralytic polio die due to the paralysis of muscles used for breathing, although this varies by age, with 2–5% of children and up to 15–30% of adults dying of the disease [42]

There is no cure for polio and treatment is mainly supportive, with assisted-breathing required for those suffering paralysis of the respiratory muscles. 

Recommendations for Travellers
The risk to the traveller is very low in most parts of the world, but individuals travelling to endemic regions may be recommended a single course injection of a combination vaccine which helps to protects adults against polio, diphtheria and tetanus. Children normally receive these vaccinations as part of the national schedule in the UK.

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Polio vaccination. Here’s the point...

Polio is a very serious disease that has almost been eradicated globally through national vaccination schemes. It is important to ensure that UK residents and travellers alike have been vaccinated against the disease.

Public Health England and NaTHNaC strongly urge travellers going to the affected countries for more than 6 months to visit their GP or travel clinic to ensure they have a booster dose of polio, if they had not received vaccination in the past 12 months [44].