British health officials have declared a national case after finding evidence suggesting a local epidemic of poliovirus in London.
So far, no cases of polio have been identified and the risk to the general public is low. However, health officials have urged people who are not completely immune to poliovirus, especially infants, to look for a vaccine immediately.
“Most of the UK’s population is protected from vaccination during childhood, but in some low-vaccination communities, individuals may remain at risk,” said the UK Health Department. Dr. Vanessa Saliva, a consultant epidemiologist, said.
The last case of polio in the United Kingdom was in 1984, which was declared a polio-free country in 2003. Prior to the introduction of the polio vaccine, the epidemic was common in the United Kingdom, with up to 8,000 cases of paralysis reported each year.
According to Dr. Shahin Huseynov, World Health Organization’s vaccine preventable technology director, regular monitoring of the country’s sewers detects poliovirus once or twice a year, but from February to May. In the meantime, the virus was identified in several samples collected in London. European disease and immune program.
Genetic analysis suggests that the samples have a common origin, perhaps individuals who traveled to the country around the New Year, Dr. Huseynov said. The last four samples collected are probably unvaccinated children and appear to have evolved from this initial introduction.
“The importance of this finding is that it is still important to make the vaccine accessible to all children, even in developed countries where the coverage of regular vaccination is very high,” he said. rice field.
UK authorities are currently collecting additional samples to identify the source of the virus. However, it is difficult to identify the source because the wastewater treatment plant that identified the sample covers about 4 million people, which is almost half of the city.
Polio is most often spread by infected people who do not wash their hands properly and come in contact with food or water ingested by others. The virus propagates in the intestines and appears in the feces of infected people. In up to 1% of patients, the virus can infect the spine and cause paralysis.
“Most of the illnesses are asymptomatic and only one in 500 children are actually paralyzed,” he said. Dr. David Hayman, an infectious disease expert at the London School of Hygiene and Tropical Medicine, who previously led the WHO Polio Eradication Program.
In the UK, polio immunization is done with an injected inactivated poliovirus, which cannot be excreted from the faeces. However, some countries in the world rely on oral polio vaccines, which contain live attenuated viruses. Immunized people can temporarily shed this virus in the faeces and then can appear in the sewage.
That’s what health officials believe happened in this case. According to Dr. Huseynov, the virus in the collected samples came from a type of oral polio vaccine used to contain the outbreak.
In recent months, he said, that type of vaccine has only been used in Afghanistan, Pakistan, and some countries in the Middle East and Africa.
Wild poliovirus has been eliminated from all countries of the world except Afghanistan and Pakistan. However, vaccine-derived polio continues to cause small outbreaks, especially in low-vaccination communities.
“Polio survives in some of the poorest parts of the world. Until it is eradicated around the world, the risk of imports and proliferation in the UK and elsewhere will continue,” said Imperial College London. Vaccine epidemiologist Nicholas Glasley said.
The analysis so far probably suggests community communication among young children. Although unlikely, even one person with immunodeficiency may have been carrying the virus for several months.
“The big question here is whether it’s in continuous circulation in the UK or is it a person with immunodeficiency,” said Emory Vaccine Center Deputy Director and Former Director of the US Immune Program. Dr. Walter Orenstein said.
In the latter case, Orenstein said, “They need to find the person with the immunodeficiency.”
