Michigan to begin testing wastewater for polio

The Detroit Free Press
The Detroit Free Press

The U.S. Centers for Disease Control and Prevention announced Wednesday it will begin testing wastewater samples for polio in Michigan and Pennsylvania as part of an effort to target parts of the country with low poliovirus vaccination rates and connections to New York communities where the virus was identified over the summer.

Testing will begin in a few weeks and is likely to include sewer samples from Oakland County, said Chelsea Wuth, a spokesperson for the state health department.

"Oakland is preliminarily where we are looking in consultation with CDC due to history of (vaccine-preventable disease) outbreaks," she said. "But we continue to triangulate where we have low coverage, risk of importation, previous vaccine-preventable disease outbreaks and appropriate sewer sampling locations."

Why is polio such a concern?

Polio, a viral scourge that killed and crippled thousands of children in the 1940s and '50s, was thought to be eradicated in the United States. But a case was identified over the summer in a man from Rockland County, New York. He contracted vaccine-derived paralytic polio .

Since then, wastewater surveillance detected the virus in at least 82 sewage samples not only in Rockland County, but also in Orange, Sullivan and Nassau counties along with New York City, suggesting the virus has been spreading undetected for months in that region, according to the New York state health department.

The Rockland County case is only the second in the U.S. since 1979 with known community transmission of poliovirus, according to a CDC a report published in August.

The man was unvaccinated when he became ill in June with fever, neck stiffness, back and abdominal pain, constipation and weakness in his lower extremities.

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How will wastewater testing for polio help?

Poliovirus is shed in the feces of people who are infected and can be detected in wastewater.

"Finding vaccine-derived poliovirus ... in sewage or wastewater indicates that someone in the community is shedding poliovirus that could infect and cause disease in an unvaccinated person," Wuth said. "If found, the concern is that the viruses are being detected in communities that have low vaccination rates and many individuals at risk for becoming infected and developing polio."

Polio can spread silently through communities before anyone knows it's there. That's because most people who catch the virus don't have any symptoms. For 25% of people, symptoms are flu-like and can include:

  • Sore throat
  • Fever
  • Exhaustion
  • Headache
  • Nausea
  • Stomachache

It's the severe cases that can be devastating.

Anywhere from one to five in 100 people who contract polio can develop meningitis. That can cause potentially life-threatening swelling of the brain or the lining around the spinal cord, according to the CDC .

A smaller proportion of people are paralyzed by the virus, which can lead to permanent disability and, in some cases, death.

Even children who seem to recover can suffer from post-polio syndrome years later as adults, which can include muscle pain, weakness, muscle atrophy and joint pain.

Those at highest risk for illness from polio are those who are unvaccinated or undervaccinated — meaning they didn't complete the full vaccine series, which is four doses given between the ages of 2 months and 6 years. The vaccine offers 99% protection against severe disease, according to the CDC.

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Michigan is at risk for polio cases

Testing will give health leaders an idea of whether the virus is silently spreading in Michigan. Although it won't be able to pinpoint who is infected or exactly how many people have the virus, testing will give health officials a better idea of where to aim efforts to boost vaccinations.

About one-third of Michigan toddlers are not up to date on the primary childhood vaccine series — which includes immunizations for polio, measles, tetanus, whooping cough, hepatitis and pneumonia, according to the Michigan Care Improvement Registry . That means they're at risk.

In seven Michigan counties and the city of Detroit, the vaccination rate for the primary childhood series for toddlers has fallen below 60%.

  • Oscoda County has the lowest immunization rate in Michigan. It's where just 28.9% of toddlers are up to date on their vaccines, according to the state registry .
  • That's followed by the city of Detroit, which has a completion rate of 47.2%.
  • Others at highest risk are Keweenaw (52.4%), Gladwin (56.9%), Leelanau (58.4%), Iron (58.5%), Sanilac (58.8%), and Lake (59.8%) counties.

Oakland County links to New York

Oakland County is considered vulnerable as well because many residents have connections to New York communities where the polio was identified over the summer.

Rockland County, New York, was the site of a 2019 measles outbreak that spread to Oakland County and infected 46 people in the state — Michigan's largest measles outbreak in 28 years.

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Wastewater testing for poliovirus "is not routinely or broadly recommended," the CDC said in a statement Wednesday, adding that strict laboratory safety requirements are involved in this type of surveillance.

However, the agency aims to expand polio wastewater testing to select other parts of the U.S. in the months ahead to identify at-risk communities and "target vaccination efforts to rapidly improve local polio vaccination coverage if needed."

“Wastewater testing can be an important tool to help us understand if poliovirus may be circulating in communities in certain circumstances,” Dr. José R. Romero, director of CDC’s National Center for Immunization and Respiratory Diseases, said in a statement. “Vaccination remains the best way to prevent another case of paralytic polio, and it is critically important that people get vaccinated to protect themselves, their families and their communities against this devastating disease.”

In Michigan, wastewater samples are to be collected over at least four months and will be analyzed at the CDC’s polio laboratory.

It could be a few weeks before sampling begins in the state, Wuth said, as health leaders work with the CDC to identify the best sampling sites and methodology for testing.

"There are multiple types of tests that can be used to test for polio in wastewater, including quantitative PCR, digital droplet PCR, and sequencing," Wuth said. "At this time, the initial plan for testing these samples in Michigan is to use digital droplet PCR, and if any samples are determined to be a preliminary positive then confirmatory testing would occur at CDC."

Digital droplet PCR testing is same technology being used by most of the laboratories testing wastewater samples for COVID-19 in Michigan, she said.

"We don’t know how exactly how long it will take to get sampling underway and then ... have results," Wuth said.

In the meantime, she encouraged people to ensure they're up to date with the polio vaccine.

Contact Kristen Shamus: Follow her on Twitter @kristenshamus. Subscribe to the Free Press .

This article originally appeared on Detroit Free Press: Michigan to begin testing wastewater for polio

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