New York state and city health authorities said Friday that poliovirus, which causes paralytic polio, had been detected in samples of New York City sewage, suggesting the disease likely was circulating in the city.

Their statement followed the initial discovery of the virus in wastewater in neighboring counties in May, June and July. A man in Rockland County, north of New York City, was confirmed to have polio last month.

Health officials fear that the detection of the poliovirus in New York City could precede other cases of paralytic polio. Polio can lead to permanent paralysis of the arms and legs and even death.

In a statement Friday, 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 best way to keep adults and children polio-free is through safe and effective immunization."

The spread of the virus poses a risk to unvaccinated people, but a three-dose course of the vaccine provides at least 99% protection. Health officials are urging unvaccinated adults to get vaccinated and parents to vaccinate their children if they have not done so.

The health department reports most adults in New York City were vaccinated as children.

Overall, about 86% of children 5 and younger in New York City have been vaccinated, though the city health department said some neighborhoods were lagging.

The U.S. Centers for Disease Control and Prevention reports polio was once one of the nation's most feared diseases, with annual outbreaks causing thousands of cases of paralysis, many of them in children.

Vaccines became available in 1955, and a national vaccination campaign cut the annual number of U.S. cases to fewer than 100 in the 1960s and fewer than 10 in the 1970s.

(AS/VOA)