New York health officials detected Polio in a patient Thursday, the first case in the United States since 2013. The signature symptom of the Polio virus is paralysis, which can return later in life, years after a survivor has recovered from their initial infection.

New York health officials detected Polio in a patient Thursday, the first case in the United States since 2013. The signature symptom of the Polio virus is paralysis, which can return later in life, years after a survivor has recovered from their initial infection. / AP

A Centers for Disease Control and Prevention scientist works with polio virus material. The first case of polio in nearly decade was detected in a New York patient Thursday. The individual was unvaccinated and likely contracted the virus from an individual outside of the country.

A Centers for Disease Control and Prevention scientist works with polio virus material. The first case of polio in nearly decade was detected in a New York patient Thursday. The individual was unvaccinated and likely contracted the virus from an individual outside of the country. / CDC

Health officials in New York have discovered a case of polio in an adult — the first case in the country since 2013.

The good news is most people have nothing to worry about. "Unless you're unvaccinated," according to retired family physician and polio survivor Marny Eulberg.

The New York State Department of Health said the unvaccinated individual from Rockland County likely contracted the virus from someone outside of the country who had taken an oral polio vaccine, which hasn't been authorized for use in the U.S. since 2000.

Additional details about the patient have yet to be released, but Eulberg said this instance will likely be attributed to the oral vaccine, which contains weakened live strains of the virus.

Over time, this weaker strain of polio can mutate and behave more like a natural version of the virus and spread to unvaccinated people. This is defined as a vaccine-derived polio virus case. Had the individual in New York been vaccinated, Eulberg said, this wouldn't have happened.

The majority of people in the United States have been vaccinated against polio — nearly 93% of children have by the age of two, the CDC says — because many states children require a polio vaccine to attend school. However, some people are granted religious exemptions and a handful of states leave that decision to the parents, Eulberg notes.

"Polio is a viral infectious disease that a small percentage of cases attack the nerves in the spinal cord that tell the body what to do and then causes paralysis," she said.

Given the seriousness of the virus, New York's Rockland County is urging unvaccinated residents to get the vaccine and announced clinics to make it easy for local residents to do so.

Eulberg was infected with polio in 1950 when she was just 4 years old — five years before a vaccine was available in the United States. She was hospitalized for six months. She said her left leg was paralyzed and she required a leg brace and crutches to get around for a portion of her childhood.

By the time she was in high school she no longer needed the brace or crutches because the surviving nerves made up for the ones damaged by the virus. But 35 years later, her condition began to deteriorate.

About half of all polio survivors experience some level of paralysis later in life, she explained. Though there's no definitive answer as to why that happens, the leading theory is that the surviving nerves wear down over time.

"It's not polio coming back; we're not contagious," Eulberg said. "It's just something that happens to up to 50% of the people who had polio in the past and it happens 20 to 50 years later."

Polio has more or less been eradicated across the globe, but remains in impoverished countries that struggle with vaccination rates and clean water. Most cases remain in Afghanistan and Pakistan, according to the Centers for Disease Control and Prevention.

Rotary International and the Bill and Melinda Gates Foundation renewed their partnership in January by pledging up to $450 million to help eradicate the polio virus globally.

Editor's note: The Bill and Melinda Gates Foundation is among NPR's financial supporters.

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