An image of the polio virus under a microscope .

An image of the polio virus under a microscope . CDC file photo

How Polio Crept Back Into the U.S.

U.S. public health agencies generally don’t test wastewater for signs of polio. That may have given the virus time to circulate silently before it paralyzed a New York man.

About a month ago, British health authorities announced they’d found evidence suggesting local spread of polio in London.

It was a jolt, to be sure. The country was declared polio-free in 2003.

But at least no one had turned up sick. The proof came from routine tests of sewage samples, which can alert health officials that a virus is circulating and allow them to intervene quickly. Based on genetic analysis of those samples, officials in the United Kingdom moved to protect the city’s children by reaching out to families with kids under 5 who hadn’t been fully vaccinated.

Polio’s first appearance in almost a decade in the U.S., confirmed late last week by health officials in New York, would play out quite differently.

In the U.S., public health agencies generally don’t test sewage for polio. Instead, they wait for people to show up sick in doctor’s offices or hospitals — a reactive strategy that can give this stealthy virus more time to circulate silently through the community before it is detected.

In New York, the first sign of trouble surfaced when a young man in Rockland County sought medical treatment for weakness and paralysis in June. By the time tests confirmed he had polio, nearly a month had passed.

Because the majority of polio infections cause no symptoms, by the time there’s a case of paralysis, 100 to 1,000 infections may have occurred, said Dr. Yvonne Maldonado, a professor of pediatrics at the Stanford School of Medicine who chairs the American Academy of Pediatrics’ committee on infectious diseases.

“You’re already chasing your tail if you’re going to wait for a case to show up,” she said.

Only after the case was identified did New York health officials start the sort of surveillance the British did, testing wastewater samples from Rockland County and beyond to help determine if the virus is spreading and where. Like many parts of the U.S., New York already was collecting sewage and analyzing it to track the spread of COVID-19. Health officials say they’re now testing stored samples for signs of polio. They say they’ve detected polio in a few Rockland County samples but need to analyze more to understand what the initial results represent.

For decades, the cost of doing wastewater surveillance for diseases like polio pretty clearly outweighed the benefit.

High U.S. vaccination rates, topping 90%, made the risk of such diseases incredibly low, though there have long been pockets of population in which rates are far lower. Rockland County, a suburban area northwest of New York City, is one such place. It suffered an extended outbreak of measles, another vaccine-preventable disease, in 2018 and 2019 that was largely concentrated in its Orthodox Jewish community, where many opt out of vaccines. Several news organizations have reported that the polio patient is a member of that community.

Nationally and globally, there are signs that the pandemic has opened up new vulnerabilities to diseases long in retreat. Routine immunizations have been hindered by a host of obstacles, including COVID-19-related lockdowns and growing vaccine resistance stoked by misinformation and politicization. A recent analysis by UNICEF and the World Health Organization showed that the percentage of children worldwide who received all three doses of the vaccine against diphtheria, tetanus and pertussis — a measure of overall immunization — dropped 5 points between 2019 and 2021 and that measles and polio vaccinations fell, too. The organizations say that’s the largest sustained decline in childhood vaccinations in the roughly 30 years they’ve been collecting data.

That could create greater risk of polio, a scourge of the first half of the 20th century in the U.S. Highly contagious and potentially life-threatening, polio historically has victimized mostly young children, attacking their spinal cords, brain stems or both.

The virus spreads when fecal material or respiratory droplets from infected people get into water or food or onto other people’s hands, which they then put into their mouths. This may sound unusual, but it’s among the more common ways viruses circulate, especially among children.

Around 70% of those who are infected show no signs of the illness but can infect others. Of those who do get sick, most have mild symptoms, such as fever, sore throat, muscle weakness and nausea. But about 5 in 1,000 infected people develop irreversible paralysis.

At its peak in 1952, polio killed more than 3,000 Americans and paralyzed more than 20,000. Images of children encased in coffin-like iron lungs terrified parents. Those fears faded swiftly after the first polio vaccine was approved in 1955. Within two years, cases dropped by as much as 90%.

Since 1988, when the Global Polio Eradication Initiative began pouring billions into immunization campaigns and surveillance around the world, polio has been eradicated in much of the rest of the world. Wild polio, the kind that occurs naturally, remains endemic in just two countries, Pakistan and Afghanistan.

But there’s another kind of polio that’s circulating, one linked to the type of vaccine that’s used in much of the world, particularly lower-income countries. This oral vaccine, which hasn’t been used in the U.S. since 2000, is easy to administer — just a few drops on the tongue — and cheap to make. It uses weakened live viruses to trigger the immune system to create protective antibodies.

That brings a bonus. When the vaccinated shed the weakened live viruses in their stool, they can spread to the unvaccinated, triggering protective antibodies in them as well.

But it also brings a risk. In rare instances, when the weakened viruses circulate in people who have not had the vaccine or are under-immunized, they revert to a form that can sicken unvaccinated people, causing the disease they were meant to prevent. The injectable polio vaccine used in the U.S. contains only inactivated viruses and cannot cause this.

Cases of vaccine-derived polio have surged in recent years after global health authorities in 2016 decided to remove one strain of polio from the oral vaccine after determining that the wild version had been eradicated globally. That left a growing number of children with no immunity to the vaccine-derived version of that strain, type 2. (The injectable form of vaccine used in the U.S. conveys protection against all strains of polio.)

Type 2 vaccine-derived poliovirus is the kind that was found in the British sewage samples. It was also the kind that infected the unvaccinated Rockland County man, indicating a transmission chain from someone who received the oral polio vaccine, health officials in New York said.

Officials are still investigating where the man caught the virus, here or abroad. The Washington Post has reported that the man traveled to Poland and Hungary this year, but a spokesperson for the Rockland County Health Department said in an email, “The person did not travel outside the country during what would have been the incubation window.”

Ultimately, New York health officials will use wastewater monitoring to tell them quickly whether they have a bigger problem, essentially allowing them to test thousands of people at once for polio infection rather than individually, David Larsen, an epidemiologist and Syracuse University professor who directs the state’s wastewater surveillance network, said in an email.

Wastewater testing for polio has been a staple in developing nations for decades, but at least a few countries where cases are rare and vaccination rates are high do it, too.

The U.K. began monitoring wastewater in 2016 for polio and several other viruses that occur in the gastrointestinal tract, a spokesperson for the British health security agency said via email. (It has since added the virus that causes COVID-19 to the list.)

Israel has monitored sewage for polio since 1989. In 2013, health officials were able to detect an outbreak of wild polio just from sampling and launch a vaccine campaign in response without ever experiencing a case of paralysis. This year, though, a young child in the Jerusalem area came down with paralytic polio. Public health authorities there found additional infections through sewage tests.

Some U.S. public health officials have been skeptical of the value of such testing here.

“I’ve always been unenthusiastic about doing it for polio in the U.S. and a big supporter of doing it elsewhere, where there are deficiencies in other surveillance systems,” said Mark Pallansch, who retired in 2021 after spending much of his career working on polio eradication efforts for the Centers for Disease Control and Prevention.

COVID-19 has triggered a blast of interest in wastewater surveillance, prompting cities, states and colleges to launch programs and opening a floodgate of funding for them.

The CDC sent federal money to health departments in over 40 jurisdictions to support such tracking efforts, working with them to collect data that’s published on the agency’s National Wastewater Surveillance System website. A spokesperson said in an email that the agency was working to expand the platform to include data on other pathogens, from foodborne infections like salmonella to influenza, but not polio. Testing nationally for polio would be labor and resource intensive, requiring increases in public health laboratory capacity, the spokesperson said.

One asset of wastewater monitoring is the ability to pivot quickly to test something new.

In November 2020, the Sewer Coronavirus Alert Network, based out of Stanford and Emory universities, started daily monitoring at California wastewater plants for the virus that causes COVID-19. It’s since added monitoring for other pathogens, including COVID-19 variants, the common respiratory virus RSV and, most recently, monkeypox. Such additions are relatively economical since the network can test for multiple pathogens from a single sample, said Marlene Wolfe, one of the two principal investigators and an assistant professor at the Rollins School of Public Health at Emory.

In adding more tests, Wolfe said, the question is always whether monitoring a disease this way is likely to surface anything of enough concern to drive public health decisions.

Many question whether the expansion of wastewater testing fueled by the pandemic will last. Maldonado, the American Academy of Pediatrics’ infectious diseases committee chair, said the recent polio case is another signal that more disease tracking is critical.

“Maybe this is a clarion call for us to really start building better surveillance networks,” she said.

X
This website uses cookies to enhance user experience and to analyze performance and traffic on our website. We also share information about your use of our site with our social media, advertising and analytics partners. Learn More / Do Not Sell My Personal Information
Accept Cookies
X
Cookie Preferences Cookie List

Do Not Sell My Personal Information

When you visit our website, we store cookies on your browser to collect information. The information collected might relate to you, your preferences or your device, and is mostly used to make the site work as you expect it to and to provide a more personalized web experience. However, you can choose not to allow certain types of cookies, which may impact your experience of the site and the services we are able to offer. Click on the different category headings to find out more and change our default settings according to your preference. You cannot opt-out of our First Party Strictly Necessary Cookies as they are deployed in order to ensure the proper functioning of our website (such as prompting the cookie banner and remembering your settings, to log into your account, to redirect you when you log out, etc.). For more information about the First and Third Party Cookies used please follow this link.

Allow All Cookies

Manage Consent Preferences

Strictly Necessary Cookies - Always Active

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data, Targeting & Social Media Cookies

Under the California Consumer Privacy Act, you have the right to opt-out of the sale of your personal information to third parties. These cookies collect information for analytics and to personalize your experience with targeted ads. You may exercise your right to opt out of the sale of personal information by using this toggle switch. If you opt out we will not be able to offer you personalised ads and will not hand over your personal information to any third parties. Additionally, you may contact our legal department for further clarification about your rights as a California consumer by using this Exercise My Rights link

If you have enabled privacy controls on your browser (such as a plugin), we have to take that as a valid request to opt-out. Therefore we would not be able to track your activity through the web. This may affect our ability to personalize ads according to your preferences.

Targeting cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.

Social media cookies are set by a range of social media services that we have added to the site to enable you to share our content with your friends and networks. They are capable of tracking your browser across other sites and building up a profile of your interests. This may impact the content and messages you see on other websites you visit. If you do not allow these cookies you may not be able to use or see these sharing tools.

If you want to opt out of all of our lead reports and lists, please submit a privacy request at our Do Not Sell page.

Save Settings
Cookie Preferences Cookie List

Cookie List

A cookie is a small piece of data (text file) that a website – when visited by a user – asks your browser to store on your device in order to remember information about you, such as your language preference or login information. Those cookies are set by us and called first-party cookies. We also use third-party cookies – which are cookies from a domain different than the domain of the website you are visiting – for our advertising and marketing efforts. More specifically, we use cookies and other tracking technologies for the following purposes:

Strictly Necessary Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Functional Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Performance Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Social Media Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Targeting Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.