Polio, a potentially disabling virus long forgotten in many parts of the world, is now circulating in parts of the United States and the United Kingdom, following an outbreak in Israel that prompted the health officials to initiate vaccination campaigns to ensure public protection. .
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 isn’t vaccinated, given polio’s ability from spreading through global travel networks and sewage systems.
On Wednesday, British health authorities announced they would offer a booster dose of polio to children aged one to nine in London, after finding evidence that the virus has spread to several regions of the capital. Britain’s Health Safety Agency said samples of the polio virus were found in sewage from eight London boroughs, but there were no confirmed infections.
Still, the agency’s analysis showed that transmission likely “has gone beyond a narrow network of a few individuals.”
“We know that areas of London where polio is transmitted have some of the lowest vaccination rates,” said Dr Vanessa Saliba, a consultant epidemiologist at the UK Health Safety Agency.
LOOK | 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 could be infected with the polio virus.
The agency said it was working closely with health authorities in the United States and Israel, as well as the World Health Organization, to investigate links between the polio viruses detected in those two countries.
In July, Israel announced a recent outbreak of polio infections appeared to be under control, after several people became infected, including a girl in Jerusalem who was paralyzed and now needs rehabilitation. according to the Jerusalem Post.
Most recently, in New York State, an unvaccinated young adult suffered paralysis after a polio infection in Rockland County, an area known for low vaccination rates, which marked the first reported case in the US in nearly a decade.
Vaccination campaigns are underway as samples of the virus were also detected in wastewater from both Rockland and another county north of New York City. Officials also say hundreds more people are already infected.
“The scope may even be much greater than we can imagine or imagine,” said New York-based immunologist Dr. Purvi Parikh.
“Because vaccines have become victims of their own success, we don’t see it, so we may not even realize how widespread polio is, because for most of us who are vaccinated, really it is not [affect] We.”
Outbreaks still occur in certain countries
Before mass vaccination campaigns largely eliminated polio from circulation in higher-income countries like Canada between the 1950s and early 1990s, the virus was known to cause outbreaks and attack 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 are still common in Afghanistan, Pakistan and parts of Africa.
Parikh said polio cases are not entirely a surprise in 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 come back and be a problem,” he said.
Part of the challenge in eliminating polio worldwide stems from the vaccination approach used in certain regions. While higher-income countries now use an inactivated poliovirus vaccine that is given as a traditional vaccine, others rely on a weakened poliovirus that is easy to administer orally.
Both types of vaccine helped slow global transmission, and importantly, neither is capable of giving someone a case of symptomatic polio.
Color electron micrograph of poliovirus, taken in 1975. (US Centers for Disease Control and Prevention)
However, because the oral version ends up in the stomach, it is eventually eliminated from the body into sewage systems, where, over time, the virus can re-evolve into a form that can cause disease.
“So if you have a particular virus and the transmission of that virus in a community, it can cause a polio outbreak,” said Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto Health Network.
“And in fact, if you look in many parts of the world, there have been small outbreaks of vaccine-derived polio.”
“Polio is just a plane ride away”
Laboratory tests on the case in New York, for example, linked virus samples to transmission from someone who had received the oral vaccine, which had not been used in the US since 2000. “This suggests that the virus may have originated somewhere outside the US where [the oral vaccine] is administered”, officials said.
In London, of the more than 100 polio samples identified in sewage, most were vaccine-like viruses, according to the UK Health Safety Agencywhile others had enough mutations to more closely resemble “wild” polio that can cause serious health impacts.
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 in Manitoba.
“Polio,” he added, “is just a plane ride away.”
Another challenge in dealing with outbreaks comes from the ability of this virus to spread undetected, experts say, with most people unaware they are even infected, making countries vulnerable to slow-growing outbreaks before any patient presents with significant disease and paralysis.
“Most people will have no symptoms or mild symptoms, but about one in 200 will have significant symptoms,” Bogoch said.
LOOK | 1953, the year polio last struck Canada:
A History of Polio in Canada
A look back 40 years later, in 1953, when polio last stalked Canada. Aired on CBC’s Prime Time News on December 7, 1993.
Undervaccinated communities remain at risk
So when it comes to experiencing a future polio outbreak, how at risk is Canada? It all depends on vaccination rates both now and in the future, several medical experts said.
“If you don’t start vaccinating children in the primary series, such as measles, mumps, rubella, diphtheria, tetanus, whooping cough, polio, you run the risk of these diseases coming back,” warned Dr. Anna Banerji, pediatrician and specialist in infectious diseases. in Toronto.
The vast majority of the Canadian public has been vaccinated against polio, and while immunization rates among children ebb and flow, the latest federal data available as of 2017, approximately 90% of young children received all three required polio vaccinations.
But this coverage is not uniform across the country. Polio vaccination rates were below 90% in British Columbia and Manitoba, and close to 80% in Nunavut, while uptake in specific communities may vary and may have been disrupted by school closures of 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 regained lung function and spent the rest of their lives on the devices. (US Food and Drug Administration)
“We have our 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 programs of immunization throughout the pandemic to get children caught.
While pockets of the population could remain vulnerable to polio infection, Fatima Tokhmafshan, a researcher and geneticist at the McGill University Health Center Research Institute, said most Canadians would not have of being too worried.
“If you see something going around, it’s good to be on your guard, but don’t panic,” he said.
“So it’s important to be vigilant. And reach out to your network, your friends, your family; make sure everyone is vaccinated.”