After a man in Rockland County, New York, became the first patient to contract polio in the United States in nearly a decade, experts such as Dr. Peter Salk — whose late father, Jonas, developed a vaccine for the disease — said the public shouldn’t be alarmed but warned that children unvaccinated for polio could be at risk.

“Polio is only a plane flight away,” Dr. Salk said during a phone interview on Friday. “Here is a circumstance that demonstrated that.”

More than 60 years since Dr. Jonas Salk and his team of researchers unveiled an effective version of their polio vaccine at the University of Pittsburgh in 1955, the disease has become nearly eradicated in the United States. Ninety-two percent of the U.S. population has been inoculated against the virus.

But Dr. Salk, who serves as president of the Jonas Salk Legacy Foundation in La Jolla, California, and is a visiting professor at Pitt, said that the virus is still a threat to populations in other countries. When U.S. citizens unvaccinated against polio travel abroad, there’s always the threat that they could bring the virus home.