The Centers for Disease Control and Prevention says it has deployed a team to New York to investigate a potential outbreak of polio.

This comes after the virus was recently found in at least seven wastewater samples from Rockland and Orange counties.

The state health department says the samples are genetically linked to the polio case identified in a Rockland County resident.

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 2 months of age are up to date with their immunization — the safe protection against this debilitating virus that every New Yorker needs.”

Officials say this is evidence of transmission, the first in the U.S. in nearly 10 years.

They urge anyone who haven’t already been vaccinated against polio to do so right away.

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 paralyzed.

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 centers 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.”