Polio spreading in Britain for first time since 70s as 'national incident' declared - families urged to check children are vaccinated

Polio is believed to be spreading in Britain for the first time in decades as health experts warn the NHS to watch out for paralysis cases. The UK Health Security Agency has repeatedly detected the poliovirus in London's sewage works and has called on families to check children are fully vaccinated.

The last community outbreak in Britain was in the 1970s but health officials insist the current risk to the population is low. Oral vaccines against polio offered abroad contain an “attenuated” form of the virus - weakened in a laboratory so it cannot cause disease.

These vaccine-derived forms of the virus remain in stool and are occasionally picked up in routine UK testing of sewage samples, conducted in London and Glasgow. The oral vaccines are different to the polio injections offered in the UK which contain a completely inactivated form of the virus.

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It is thought someone from Afghanistan, Pakistan or Nigeria who had recently received the oral vaccine has seen this weakened form of the virus then mutate and passed it on to others, reports The Mirror . For the first time Britain has repeatedly detected genetically-linked samples, suggesting the virus has been spreading since February and has continued to mutate from this symptomless vaccine-derived form.

Recent fortnightly sewage samples have increased concerns it may have mutated from the harmless virus to the wild type form that was endemic in Europe from Victorian times. The UKHSA has declared a national incident and alerted the World Health Organisation, which could strip Britain of its polio-free status.

Dr Vanessa Saliba, consultant epidemiologist at