WASHINGTON (AA) - New York state health authorities on Thursday announced the first confirmed US case of polio in nearly a decade.

The infection is the first in the US since 2013. It was detected in an unvaccinated man from Rockland County, which is located northwest of New York City. The New York State Department of Health and Rockland County Department of Health said in a joint statement that they are still attempting to determine the origins of the infection.

Testing has indicated that the virus may have originated in a location outside of the US, the departments said. The 20-year-old patient, who has not been identified publicly, had traveled to Poland and Hungary earlier this year, according to the Washington Post newspaper.

He has been discharged from the hospital, and while he can stand, he is having difficulty walking, the Post reported.

Polio is an extremely contagious neurological disease that mostly affects children. Symptoms, which can take up to 30 days to appear, can be mild and flu-like, but the disease can cause paralysis and death.

The health departments have alerted local hospitals and health practitioners to be vigilant for additional cases.

While most Americans are vaccinated against polio, health authorities are urging those who are not to quickly get vaccinated.

"The polio vaccine is safe and effective, protecting against this potentially debilitating disease, and it has been part of the backbone of required, routine childhood immunizations recommended by health officials and public health agencies nationwide," said New York Health Commissioner Dr. Mary Bassett.

Native polio cases have largely been eliminated in the US since the 1960s after the vaccine began to be distributed in 1955. The last case that originated in the US was detected in 1979.

During the late 1940s, over 35,000 people were disabled by polio each year, making it one of the most feared diseases of the time.