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THURSDAY, June 23, 2022 – Health authorities in Britain, who routinely test sewer samples for the virus that causes polio, declared a “national incident” after evidence of localized spread in London’s sewers.
No cases have been identified yet, according to the UK Health Security Agency.
There is little risk to the public, UK health officials stressed, but those who have not been fully vaccinated against polio virus are urged to get their injections. This is especially important for young children.
“Most of the UK population will be protected from childhood vaccination, but in some communities with low vaccination coverage, individuals may continue to be at risk,” said Dr. Vanessa Saliba, an epidemiologist with the UK Health Security Agency, said in a statement from the agency. †
A genetic analysis of the samples points to a common origin. It is likely a person who traveled to the UK around the New Year, Dr. Shahin Huseynov, Technical Officer for the World Health Organization’s Vaccine-Preventable Diseases and Immunization Program in Europe, The New York Times†
The most recent four samples collected may have come from young children who were introduced to the virus by this person or by each other.
It’s also possible that all the samples came from a single immunocompromised person who’s been shedding the virus for months, the agency added.
“The big issue here is whether it’s circulating continuously in the UK or whether it’s an immunodeficient person,” Dr. Walter Orenstein, associate director of the Emory Vaccine Center and former director of the United States Immunization Program, at the Time†
“They need to find that immunodeficient person” if that’s the case, Orenstein added.
That may not be an easy job.
The wastewater treatment plant from which the samples have been taken includes about 4 million people, the Time said. Sample collection continues to attempt to identify the source.
It is typical of the sewer inspection to pick up one or two cases of polio every year. The last confirmed case of polio in Britain was in 1984. The country was declared polio-free in 2003.
When someone is infected, the virus lives in the gut and is excreted in the feces. It is most often spread when an infected person touches food or water intended for someone else without washing their hands.
Poliovirus can infect the spine and cause paralysis, which occurs in about 1% of patients.
“Most of the disease is asymptomatic. It’s only about one in 500 children who is actually paralyzed,” Dr. David Heymann, an infectious disease expert at the London School of Hygiene and Tropical Medicine, at the London School of Hygiene and Tropical Medicine. Time† He previously led the World Health Organization’s polio eradication program.
Wild polio now only exists in Afghanistan and Pakistan, but in some parts of the world a “live” oral vaccine is used and can be briefly excreted in the feces of a person who has been immunized.
Health officials believe this happened here because the virus in the samples matched a type of oral polio vaccine used to prevent outbreaks, Huseynov said. That vaccine has been used in Afghanistan, Pakistan and some countries in the Middle East and Africa in recent months.
“Polio persists in some of the poorest parts of the world. Until it is eradicated globally, the risk of importation and spread in the UK and elsewhere remains,” Nicholas Grassly, a vaccine epidemiologist at Imperial College London, told the Time†
Britain uses an injected inactivated polio virus for vaccination. It cannot be passed through the faeces. London has a polio vaccination rate of about 86.6%, according to the Global Polio Eradication Initiative.
The US Centers for Disease Control and Prevention has more about polio.
SOURCE: The New York Times
By Cara Murez HealthDay Reporter
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