New York state health officials issued a urgent call on Thursday (local time) for unvaccinated children and adults to get inoculated against polio, citing new evidence of possible "community spread" of the dangerous virus in the city.
The polio virus has been found in seven different wastewater samples in two adjacent counties north of New York City, health officials said.
So far, only one person has tested positive for polio — an unvaccinated adult in Rockland County who suffered paralysis.
But based on earlier polio outbreaks, "New Yorkers should know that for every one case of paralytic polio observed, there may be hundreds of other people infected," the state's health commissioner, Dr Mary T. Bassett, said in a statement.
"Coupled with the latest wastewater findings, the Department is treating the single case of polio as just the tip of the iceberg of much greater potential spread," she said. "As we learn more, what we do know is clear: the danger of polio is present in New York today. We must meet this moment by ensuring that adults, including pregnant people, and young children by two months of age are up to date with their immunisation — the safe protection against this debilitating virus that every New Yorker needs."
The polio patient in Rockland County is the first person known to be infected with the virus in the US in nearly a decade. Wastewater samples collected in June and July in adjacent Orange County also contained the virus.
Polio, once one of the nation's most feared diseases, was declared eliminated in the United States in 1979, more than two decades after vaccines became available.
A majority of people infected with polio have no symptoms, but can still shed the virus and give it to others for days or weeks. A small percentage of people who get the disease suffer paralysis. The disease is fatal for between 5-10% of those paralysed.
All school children in New York are required to have a polio vaccine, but enforcement of vaccination rules in some areas can be lax. Rockland and Orange counties are both known as centres of vaccine resistance. Statewide, about 79% of have completed their polio vaccination series by age two. In Orange County, that rate is 59%. In Rockland it is 60%.
The Orange County wastewater samples were initially collected from municipal wastewater treatment plants for Covid-19 testing.
"It is concerning that polio, a disease that has been largely eradicated through vaccination, is now circulating in our community, especially given the low rates of vaccination for this debilitating disease in certain areas of our County," said Orange County Health Commissioner Irina Gelman said. "I urge all unvaccinated Orange County residents to get vaccinated as soon as medically feasible."