What is polio? Everything you need to know from risks of drinking tap water to paralysis and symptoms
TRACES of polio, a deadly virus that can also cause paralysis, have been found in sewage samples in London.
The disease wreaked havoc in the UK in the 1950s and while no cases have yet been discovered in the country, experts have warned it poses a serious threat.
What is polio?
Polio is an infectious disease that can spread from person to person and most commonly affects children under the age of five.
The disease attacks the nervous system and in some extreme cases can lead to paralysis.
The UK Health Security Agency (UKHSA) has launched an investigation to protect the public from the spread.
In the , experts warn that the virus has been detected in samples from the London Beckon Sewage Treatment Works - as early as February.
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Since then, the virus has continued to evolve and the samples found in the UK are ‘vaccine-derived’ poliovirus type 2 (VDPV2).
The paper, published yesterday stated: "The detection of a VDPV2 suggests it is likely there has been some spread between closely-linked individuals in North and East London and that they are now shedding the type 2 poliovirus strain in their faeces.
"The virus has only been detected in sewage samples and no associated cases of paralysis have been reported – but investigations will aim to establish if any community transmission is occurring."
Head of the vaccine epidemiology research group at Imperial College London, Prof Nicholas Grassly said there is concern that the virus may be circulating locally in London and could spread more widely.
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Is it contagious?
Poliovirus is very contagious and spreads through person-to-person contact.
It lives in an infected person's throat and intestines.
The NHS says polio is caused by a virus that spreads easily when an infected person coughs or sneezes.
How is it transmitted?
A person can transmit (spread) it even if they aren’t sick.
Symptoms usually occur six to 20 days with a range of three to 35 days.
The virus can spread from person to person in two ways, including through coughs and sneezes.
But people who are infected with the disease can spread the virus through their faeces.
The virus can then spread to other people when they swallow contaminated water or food.
What are the symptoms?
Most people infected with poliovirus will have no signs of the disease or mild symptoms at most.
If symptoms do occur, they usually appear about seven to 10 days after exposure to the virus.
However, symptoms can take as long as 35 days to show up.
The early symptoms of polio last about two to 10 days include:
- Fatigue
- Fever
- Headache
- Neck stiffness
- Pain in the arms and legs
- Vomiting
In rare cases, polio can cause people to experience difficulty using their muscles.
This is usually in the legs and can happen over hours or even over the course of a few days.
Medics say that in most cases, this isn't permanent and movement usually comes back in a few weeks or months.
However, it can be life-threatening if the paralysis affects the muscles used for breathing.
Can I drink tap water?
Exposure to polio is more likely in areas that have poor hygiene or weak systems to clean water.
In the UK, polio samples were found in North and East London.
Thames Water is the company that looks after the water supply in London and it has not issued any guidance to residents regarding the consumption of tap water.
If the provider has issued no warnings - then the tap water is safe to drink.
Water is treated before it comes through the taps that consumers use - making sure any bugs or bacteria is killed in the process.
Never drink tap water if it has changed colour or tastes strange and always contact your provider.
Thames Water previously issued guidance on taking care when handling sewage.
It states: "We test our treated water regularly to check its quality. All our staff follow governmental guidance, and our own high standards, for personal hygiene and health and safety.
"We advise customers to always take great care when close to or handling sewage.
"We advise wearing gloves and, if possible, other protective clothing when working to clear a drain, for example. The government advises thorough washing following any contact with faecal matter."
Am I protected?
The polio vaccine is part of the UK's routine childhood vaccine schedule.
This means most people in London - where the illness has been detected, are likely to have had their jabs due to the national rollout.
Jane Clegg, Chief nurse for the NHS in London said: "The majority of Londoners are fully protected against polio and won't need to take any further action,
"But the NHS will begin reaching out to parents of children aged under five in London who are not up to date with their polio vaccinations to invite them to get protected."
The vaccine is given when a child is:
- Eight, twelve and sixteen weeks old as part of the six-in-one vaccine
- Three years and four months old as part of the four-in-one pre-school booster
- Fourteen years old as part of the three-in-one teenage booster
All three vaccines are required to be fully vaccinated against polio.
In order to get the vaccine, simply call up your GP and request it - they will be able to check your medical records and you can also check you child's red book to see if they have had it.
Most health care clinics also offer the vaccine such as Superdrug Health clinic and Boots Healthcare.
No vaccine provides a level of protection where there is no risk of getting the disease after being vaccinated.
However, two doses of IPV provide 90 per cent immunity (protection) to all three types of poliovirus.
Whereas three doses provide at least 99 per cent immunity.
A timeline of the poliovirus
Polio is a condition that mainly affects children under the age of five.
Data from previous outbreaks shows that one in 200 infections leads to irreversible paralysis.
Of those five to ten per cent die.
Some of the first evidence of polio comes from Ancient Egypt.
A tablet from a stone carving in 1403-1365 BC showed a priest with characteristics of polio.
1798: It was given its first clinical description by the British physician Michael Underwood
1840: Was recognised as a condition by Jakob Heine
1840 - 1900: In the UK polio was a major health crisis in the Victorian England and there were also major incidents in Europe.
1916: New York experienced the first large epidemic, there were more than 9,000 cases and 2,343 deaths.
1928: Philip Drinker and Louie Shaw develop the 'iron lung' technology to help have children ravaged by the condition. Kids would spend two weeks in the device, which has today been made redundant by vaccinations.
1950: The illness wreaked havoc in the UK at this time. The country was rocked by a series of polio epidemics, with as many as 8,000 people suffering paralytic poliomyelitis.
1952: US saw over 57,000 cases. It was also in 1952 that Dr Jonas Salk started to develop a vaccine.
1953: Cases started to fall as jabs were rolled out.
1961: The oral polio vaccine was rolled out. Despite the advances, at this time there were still 79 deaths in the UK and 707 acute cases.
1962: Brits started to use the oral vaccine.
1988: Polio had disappeared from the UK, US and much of Europe but was still around in more than 125 counties.
1994: World Health Organization Americas region is certified polio free
1997: Last wild cases in the Western Pacific region are recorded
2002: Europe is certified polio-free
2011: China returned to its polio-free status
2012: At this point, polio is still endemic in Afghanistan, Nigeria, Pakistan and India.
2013: Outbreak in Syria
2015: Polio endemic in Pakistan and Afghanistan
2016: Case of polio in Nigeria
2020: Type 1 was only in circulation in Pakistan and Afghanistan, while type 2 and 3 have been eliminated for over a decade.
2021: Five cases of polio globally
February 2022: First case of polio detected in Africa in five years, leaving a three-year-old girl in Malawi paralysed
Who is most at risk?
People are most at risk of polio if they have not had their vaccine.
The NHS states: "You can have a polio vaccination at any point if you've never had one before, even if you're not travelling to a country with a risk of getting polio.
"You should also get vaccinated even if you've had polio before as it protects against different types of polio."
It mainly affects children under the age of five.
Those living in unhygienic conditions are also more prone to contracting it and infections are more common during the summer and autumn.
When was the last case in the UK?
Medics yesterday warned that the emergence of polio in the UK reminds us that it has not yet been eradicated.
The last case of polio being contracted in Britain was in 1984 and the country was declared polio-free in 2003.
Before a vaccine was introduced in the 1950s, epidemics would result in thousands of people being paralysed annually and hundreds of deaths.
Experts believe a traveller – likely from Pakistan, Afghanistan or Nigeria - shed the virus in their stools after being given the oral polio inoculation.
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But the bug has now spread to others after mutating, with the same strain being repeatedly detected in sewage samples.
Despite clear evidence of an outbreak, no cases have yet come forwar
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