Wastewater surveillance uncovers possible polio threat
Routine surveillance has found poliovirus in sewage samples collected from London’s Beckton Sewage Treatment Works in the east of the capital.
Investigations are underway after several closely-related viruses were found in sewage samples taken between February and May. Experts have classified the virus as a “vaccine-derived” poliovirus type 2 which can cause serious illness, such as paralysis, in people who are not fully vaccinated. This however is reportedly rare.
Vaccine derived polioviruses usually come from individuals entering the UK who have been vaccinated overseas with the live polio vaccine, which is administered orally. They can shed traces of the vaccine-like poliovirus in their faeces. Orally administrated live vaccine is no longer used in the UK where a jab of inactivated virus is used.
The UK Heath Security Agency (UKHSA), working with the Medicines and Healthcare products Regulatory Agency (MHRA), have advised that it is normal for routine surveillance, to uncover one-to-three, one-off findings of polioviruses each year in UK sewage samples.
The latest finding of a vaccine derived virus reportedly suggests has been spread between closely-linked individuals in North and East London and that they are now shedding the poliovirus strain in their faeces.
The virus has only been detected in sewage samples with no reports of associated cases of paralysis. Investigations will aim to establish if any community transmission is occurring.
Consultant Epidemiologist at UKHSA, Dr Vanessa Saliba, said the risk to the public overall from the current, Becton finding is “extremely low”. She went on to explain that vaccine-derived poliovirus has the potential to spread, particularly between people who are not fully vaccinated. The UK was declared polio-free by the World Health Organisation in 2003.
Chief nurse for the NHS in London, Jane Clegg, said: “Most of the UK population will be protected from vaccination in childhood, but in communities with low vaccine coverage, individuals may remain at risk. Vaccine coverage for childhood vaccines has decreased across the UK and especially in parts of London, so UKHSA is urging people to check they are up to date with their vaccines.”
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