NEW YORK (AP) — The polio virus has been found in New York City’s wastewater in another sign that the disease, which hadn’t been seen in the U.S. in a decade, is quietly spreading among unvaccinated people, health officials said Friday.

The presence of the poliovirus in the city’s wastewater suggests likely local circulation of the virus, the city and New York state health departments said.

State Health Commissioner Dr. Mary T. Bassett said the detection of poliovirus in wastewater samples in New York City is alarming but not surprising.