The case of the patient, who has only been reported to be a resident of Rockland County, is not contagious, but has developed paralysis due to the virus, the medical report specifies.
The authorities assure that the young man was not vaccinated and that, almost certainly, he was in contact with a person who received a vaccine that contains the weakened live virus.
The last known case of this highly contagious virus in the North American country was recorded in 2013.
A dangerous enemy reappears
The disease, once widely feared, was eradicated thanks to a national vaccination campaign that began in 1955.
Immunization allowed cases to drop from 100 in the 1960s to less than 10 in the 1970s . In 1979 , the US declared polio eradicated .
Since then, isolated cases of polio infection have occurred in the country through foreign travellers.
The virus, which primarily affects children, causes muscle weakness and paralysis, and in the most severe cases permanent disability and death.
Americans are typically vaccinated with three or four doses beginning at two months of age. About 93% of young children have received at least three doses of the polio vaccine , according to vaccination data from the Centers for Disease Control and Prevention (CDC).
The possible origin
Vaccines made with an inactivated version of the virus are used in the United States, but other countries give a vaccine by mouth that uses the virus in a live, weakened form. That weakened virus can, on rare occasions, mutate and cause a new outbreak.
Like the Rockland County patient, the last recorded case of polio in the US — a 7-month-old boy who moved from India to Texas in 2013 — was a vaccine-derived strain.
The news has prompted local authorities to schedule vaccination drives across New York state for next week.
"We want vaccines to reach those who need them ," Dr. Patricia Schnabel Ruppert, Rockland Health Commissioner, said at a news conference Thursday.
Polio is endemic in Afghanistan and Pakistan, but has recently been reported in other parts of the world as well. Weeks ago, UK health authorities detected the virus in London sewage.