How does polio spread? What are the symptoms? Here’s what we know

The polio virus is considered very contagious and spreads mostly from person to person, through contaminated water and via fecal particles.

The polio virus has been found in New York City sewage, but officials are stressing that the highest risk is for people who haven’t been vaccinated.

Polio was once one of the nation’s most feared diseases, with annual outbreaks causing thousands of cases of paralysis. Its elimination in the U.S., officially declared in 1979, is considered one of the nation’s greatest public health victories. Yet cases have cropped up occasionally since then, often among people who had traveled to other countries.

Recently, an unvaccinated young adult north of New York City contracted polio. On Friday, health officials in the nation’s largest city said they had found the virus in wastewater samples, suggesting it was spreading among the unvaccinated.

Here are some details on polio and the vaccine:

Polio is considered very contagious and spreads mostly from person to person, through contaminated water and via fecal particles.

Health officials say the virus also can spread through droplets from an infected person’s cough or sneeze, though that is less common.

Most infected people have no visible symptoms. About a quarter will endure a few days of flu-like symptoms, such as fever, sore throat, headache and nausea.

A small fraction of people, however, can get more serious illness. The virus can infect a person’s spinal cord, causing paralysis and possibly permanent disability and death.