New evidence suggests polio may be spreading in New York’s Hudson Valley.

The virus was detected in four wastewater samples taken from two different parts of Orange County in June and July, according to the latest analysis from the U.S. Centers for Disease Control and Prevention. State health officials shared the findings with the Orange County Department of Health on Tuesday, according to a notice posted on the state health department’s website.

The findings come shortly after the CDC detected polio in Rockland County’s wastewater, where it’s now been found in three sewage samples. The disease was apparently present there in June, the month before a Rockland County resident tested positive for the disease. The seven samples taken from Rockland and Orange counties are all genetically linked to the strain of polio detected in the Rockland County resident, the state health department said in an announcement sent out Thursday evening.

“These environmental findings — which further indicate potential community spread — in addition to the paralytic polio case identified among a Rockland County resident, underscore the urgency of every New York adult and child getting immunized against polio, especially those in the greater New York metropolitan area,” state health officials cautioned in the post.

They said the Rockland County case was found to be genetically linked to similar wastewater specimens found in Jerusalem and London. But the agency clarified that does not necessarily mean the person who contracted the disease traveled to those places.

No cases of polio have been reported in Orange County so far, but the wastewater detection suggests it’s somewhere in the community.

“It is disheartening to see a resurgence of polio, a disease that was largely eradicated long ago,” Dr. Irina Gelman, Orange County’s health commissioner, said in a statement. “It is concerning that polio is circulating in our community, given the low rates of vaccination for this debilitating disease in certain areas of our county.”

State data shows that only 62% of 2-year-olds in Orange County are fully vaccinated against polio, compared with 80% statewide.

This story was updated with additional details released Thursday evening from the New York State Department of Health.