The health authorities suspect that the pathogen was brought in from abroad. There is no danger to the population.
Thanks to vaccinations – pictured in a clinic in Kyiv – polio has been eliminated in most countries.
According to media reports, the causative agent of polio was discovered in sewage samples in London. The disease has been considered eliminated in the UK since 2003; the last case of illness occurred in 1984. The health authorities assess the risk from the latest discovery for the population as low. So far, no case of illness has become known in the country. Parents are advised to ensure their children are fully vaccinated against polio.
The government agency responsible for national health protection, the UK Health Security Agency, assumes that the polioviruses in sewage were brought to London by a person who was vaccinated abroad with the live form of the pathogen. With this oral vaccination, the virus can multiply in the body of the vaccinated person and get into the waste water via intestinal excretions. In rare cases, such a live vaccine virus can also be transmitted to other people.
The live-form polio vaccine has not been used in the UK since 2004. To date, however, all children are routinely vaccinated against the disease with an inactivated vaccine. Vaccination rates are lower in London than anywhere else in the country. Nationally, 92 percent of children received the three shots needed for full immunization; in London it is 86 percent.
According to the British health authorities, it is not unusual for isolated cases of poliovirus to be found in sewage. This time, however, the viruses – which are genetically closely related – appeared for over four months and in many different water samples from north and east London. The authorities therefore assume that the pathogen was spread between people in London. They have reported the national incident to the World Health Organization (WHO).
The so-called wild polioviruses are now rare and only found in a few countries. According to the WHO, the annual reported cases of disease have fallen by 99 percent since 1988: from around 350,000 cases in more than 125 countries to 175 cases in 2019. Vaccinated live polioviruses have caused several hundred diseases since 2000. These viruses circulate primarily in regions with low vaccination coverage. Poliovirus is most commonly transmitted from person to person through the faeces (faecal-oral) and through contaminated water and food. The disease usually progresses without symptoms. Occasionally, however, the infected develop flu-like symptoms, which can lead to the dreaded symptoms of paralysis by affecting nerves and the brain. Children up to the age of five are particularly affected by polio.