Polio, a potentially debilitating virus long forgotten in many parts of the world, is now circulating in parts of the US and UK, on the heels of an outbreak in Israel – prompting health officials to launch vaccination campaigns to ensure the public is protected.
Even in Canada, a polio-free country for the past two decades, medical experts say it’s a wake-up call that the virus still poses a threat to anyone who remains unvaccinated, given polio’s ability to spread through global travel networks and waste water systems.
On Wednesday, British health authorities announced they would offer a polio booster to children aged one to nine in London after finding evidence that the virus was spreading in multiple regions of the capital. Britain’s Health Security Agency said samples of the polio virus had been found in sewage from eight London boroughs, but there were no confirmed infections.
Still, the agency’s analysis showed the transmission likely “went beyond a narrow network of a few individuals.”
“We know that areas of London where polio is transmitted have some of the lowest rates of vaccination,” said Dr Vanessa Saliba, a consultant epidemiologist at the UK’s Health Security Agency.
WATCH | Hundreds may be infected with polio in New York state, officials say:
100 people may be infected with polio in New York, health officials say
A New York state health official says hundreds of people may be infected with the polio virus.
The agency said it is working closely with health authorities in the US and Israel, as well as the World Health Organization, to investigate links between the polio viruses found in those two countries.
In July, Israel announced that a recent outbreak of polio infections appeared to be under control after scores of people became infected, including a Jerusalem girl who was paralyzed and now needs rehabilitation. according to the Jerusalem Post.
Most recently in New York State, an unvaccinated young adult suffering from paralysis after poliomyelitis infection in Rockland County — an area known for low vaccination rates — which marked the first case reported in the U.S. in nearly a decade.
Vaccination campaigns are now underway because samples of the virus have also been found in the wastewater of both Rockland and another county just north of New York. Officials also say hundreds more people may already be infected.
“The scope may be even much greater than we can even fathom or imagine,” said New York-based immunologist Dr. Purvi Parikh.
“Because vaccines have become a victim of their own success, we don’t see it – so we may not even realize what the spread of polio is, because for most of us who are vaccinated, it’s not really [affect] us.”
Outbreaks are still occurring in some countries
Before mass vaccination campaigns largely eliminated polio in higher-income countries like Canada between the 1950s and early 1990s, the virus was known to cause outbreaks and strike children. causing paralysis or death in some cases.
Even now, war, poverty and social unrest make eradication difficult to achieve in many countries around the world. Outbreaks remain frequent in Afghanistan, Pakistan and parts of Africa.
Parikh said polio cases are not a complete surprise to any community where vaccination rates are lower, either because of anti-vaccine sentiment or disruptions to routine immunizations during the COVID-19 pandemic.
“The concern now is that some of these infectious diseases that we haven’t seen in almost decades may actually come back and be a problem,” she said.
Part of the challenge in eliminating polio around the world actually comes from the vaccination approach used in certain regions. While higher-income countries now use an inactivated polio vaccine given as a traditional injection, others rely on weakened polio that is easily administered orally.
Both types of vaccine have helped limit global transmission, and most importantly, neither is capable of infecting someone with symptomatic polio.
Color electron micrograph of poliovirus taken in 1975 (US Centers for Disease Control and Prevention)
However, as the oral version ends up in the stomach, it is eventually flushed out of the body into sewage systems – where over time the virus can evolve back into a form capable of causing disease.
“So if you have an isolation of that particular virus and transmission of that in a community, that could cause a polio outbreak,” said Dr. Isaac Bogoch, an infectious disease specialist at the University Health Network in Toronto.
“And in fact, if you look at many parts of the world, there are small outbreaks of vaccine-derived polio.”
“Polio is just a plane ride away”
Laboratory tests conducted on the New York case, for example, linked samples of the virus to transmission from someone who received the oral vaccine, which has not been used in the U.S. since 2000. “This suggests that the virus may have originated locally outside the US where [the oral vaccine] is administered”, officials said.
In London, of more than 100 polio samples identified in sewage, most were vaccine-like viruses, according to the UK’s Health Security Agencywhile others have had enough mutations to look more like “wild” polio, which can cause serious health consequences.
Global travel between countries with high rates of polio transmission and regions with lagging vaccination rates could pose a problem in the future, said Wes Hazlitt, a Winnipeg polio survivor, advocate and president of the Post-Polio Network of Manitoba.
“Polio is only a plane ride away,” he added.
Another challenge in dealing with outbreaks stems from the ability of this virus to spread unnoticed, experts say, with most people not even knowing they are infected – leaving countries vulnerable to slow-growing outbreaks before patients become seriously ill and paralyzed .
“Most people will have no symptoms or mild symptoms, but about one in 200 or more will have significant symptoms,” Bogoch said.
WATCH | 1953, the year polio last struck Canada:
History of poliomyelitis in Canada
A look back 40 years later to 1953, when polio last struck Canada. Aired on CBC prime time news on December 7, 1993.
Undervaccinated communities remain at risk
So when it comes to experiencing a future polio outbreak, what risk is Canada at? It all depends on vaccination rates both now and in the future, multiple medical experts said.
“If you start not vaccinating kids in the primary series — like measles, mumps, rubella, diphtheria, tetanus, whooping cough, polio — then you risk those diseases coming back,” warned Dr. Anna Banerjee, a pediatrician and infectious disease specialist in Toronto. .
The majority of the Canadian population is vaccinated against polio, and while immunization rates among children are declining, the most recent federal data available as of 2017 shows that approximately 90 percent of young children have received all three required polio vaccines.
But this coverage is not uniform across the country. Polio vaccination rates were below 90 percent in British Columbia and Manitoba and close to only 80 percent in Nunavut, while uptake in specific communities may vary and may have been disrupted by school closures due to COVID-19.
Polio wards were lined not only with beds but also with iron lungs, large metal ventilators that helped patients breathe during the worst of the infection. Some survivors never recovered their lung function and spent the rest of their lives in the devices. (US Food and Drug Administration)
“We do have problems in Canada, with undervaccinated communities for a variety of reasons, and a lot of that predates COVID-19,” Bogoch said, adding that many public health teams across the country offered immunization programs during the flu pandemic. the children.
Although parts of the population may remain vulnerable to polio infection, Fatima Tokhmafshan, a researcher and geneticist at the Research Institute at McGill University Health Center, said most Canadians should not worry too much.
“If you see something circulating, it’s good to be alert, but not to panic,” she said.
“So it’s important to keep an eye out. And to reach out to your network, your friends, your family – make sure everyone is vaccinated.”
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