PUBLIC HEALTHHow Polio Crept Back into the U.S.

By Robin Fields

Published 8 August 2022

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.