A polio outbreak has been detected in the UK and parents are being urged to check their children's vaccines are up to date.
The virus, which was officially eradicated in 2003 in the UK, has been detected in sewage samples.
The UK Heath Security Agency (UKHSA) said waste from the London Beckton Sewage Treatment Works, which serves north and east of the capital, tested positive between February and May.
Polio is a contagious viral illness that can cause paralysis and, in some cases, be life-threatening.
The virus has only been detected in sewage samples and no cases of paralysis have been reported, the UKHSA stressed.
Here is everything you need to know about polio, including vaccinations and how to recognise the signs.
What is polio?
Polio is caused by a virus that spreads easily when an infected person coughs or sneezes.
It can also be caught from food or water that's been in contact with the poo of someone who has the virus.
Due to high vaccination rates, it is now very rare in most parts of the world. Cases are mostly found in Afghanistan and Pakistan.
When is the polio vaccine given in the UK?
Children in the UK are given the polio vaccine starting when they are just weeks old.
On the NHS, the polio vaccine is given when a baby is eight-weeks-old, then at 12 and 16 weeks, as part of the 6-in-1 vaccine.
The vaccine is given again at three years and four months old as part of the 4-in-1 (DTaP/IPV) pre-school booster, and at 14 as part of the 3-in-1 (Td/IPV) teenage booster.
The UK stopped using live oral polio vaccine (OPV) in 2004 and switched to inactivated polio vaccine (IPV).
What are polio symptoms?
Most people who get polio don't have symptoms.
The NHS says some people may come down with mild, flu-like symptoms, lasting up to 10 days such as:
- A high temperature
- Extreme tiredness (fatigue)
- Headaches
- Being sick (vomiting)
- A stiff neck
- Muscle pain
In rare cases, the polio virus causes nerve injury that leads to paralysis, usually in the legs, that happens over hours or days.
It's not usually permanent and movement will slowly come back over the next few weeks or months. The paralysis can be life threatening if it affects the muscles used for breathing.
What are the urgent signs of polio?
Medics have now been alerted by UKHSA to look out for signs of polio paralysis.
Urgent medical attention should be sought if people experience rapid onset of weakness in a limb, which will be floppy, or difficulties with breathing.
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