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.

“The risk to New Yorkers is real but the defense is so simple – get vaccinated against polio,” New York City Health Commissioner Dr. Ashwin Vasan said in a statement. “With polio circulating in our communities there is simply nothing more essential than vaccinating our children to protect them from this virus, and if you’re an unvaccinated or incompletely vaccinated adult, please choose now to get the vaccine. Polio is entirely preventable and its reappearance should be a call to action for all of us.”