Polio Symptoms and Prevention: What to Know

During the slog of yet another Covid wave, and mounting monkeypox anxieties, health officials reported a case of polio in a New York suburb in July — the first detected in the United States in nearly a decade.

State health officials said that polio was detected in an unvaccinated person in Rockland County, New York, and that the virus had been found in county wastewater samples in June, as well as in wastewater samples in two different locations in Orange County, New York, in June and July. On Aug. 12, health officials announced that poliovirus had been detected in sewage samples in New York City, indicating that the virus is likely circulating there too.

These occurrences, as well as reports that health officials in Britain had detected evidence of poliovirus in sewage samples in London, have reignited polio concerns. However, experts said that people who are vaccinated against polio do not need to change their daily behaviors or panic about the disease.

Here’s what you need to know.

What is polio?

Polio, also known as poliomyelitis, is a sometimes disabling and life-threatening disease caused by the poliovirus. The disease mainly affects infants and children under 5, but anyone who is unvaccinated can contract it.

There is no cure for polio, but widespread vaccination has proved to be an effective prevention strategy. No cases have originated in the United States since 1979, and before July, there hadn’t been a reported U.S. case since 2013.

What are the symptoms of polio?

During the early 1950s, before vaccines were widely available, polio outbreaks caused more than 15,000 cases of paralysis each year. But that symptom is rare — and many people don’t develop any visible symptoms of the virus at all.

“Most people who get polio will not even know they got polio,” said Dr. Frank Esper, a pediatric infectious diseases specialist at the Cleveland Clinic in Ohio. Seventy-two percent of people who contract it are asymptomatic, according to the Centers for Disease Control and Prevention.

About a quarter of those infected experience flulike symptoms, but “it’s more the stomach flu than a cold flu,” Dr. Esper said. Typically, symptoms like sore throat, fever, fatigue, nausea, headache and stomach pain last for around three to seven days, he said, but people can still spread polio for three or more weeks.

A smaller subset of people who contract polio (less than one in 100, according to the C.D.C.) develop symptoms that affect the brain and spinal cord. Some of those people may experience a tingling sensation in their legs, often described as pins and needles. Others, about one in 25 people, may develop meningitis, which involves swelling of the membranesthat cover the brain, spinal cord or both.

The C.D.C. estimates that one in 200 people with polio experience paralysis or weakness in the arms, legs or both. Paralysis typically occurs on one side of the body, said Dr. Gail Shust, a pediatric infectious disease specialist at NYU Langone Health. In rare cases, polio-related paralysis can be fatal, as the virus may affect muscles that support breathing.

Even after someone recovers from polio, they can develop muscle pain, weakness or paralysis 15 to 40 years later. Children who recover from polio may experience post-polio syndrome as adults, with muscle weakness, fatigue and joint pain setting in decades after their initial infection. It’s