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The World Health Organization has added the U.S. to its list of countries with circulating polio. It joins the likes of Somalia, Yemen, and Israel

September 13, 2022, 8:46 PM UTC
A boy receives a polio vaccine in Kolkata, June 19, 2022.
Sankhadeep Banerjee—NurPhoto/Getty Images

The U.S. has been added to the World Health Organization’s list of countries with circulating polio, the U.S. Centers for Disease Control and Prevention announced Tuesday. 

It now joins roughly 30 other countries with outbreaks, including Algeria, Burkina Faso, Sierra Leone, Somalia, Yemen, Israel, and the U.K.

“We cannot emphasize enough that polio is a dangerous disease for which there is no cure,” Dr. José R. Romero, director of CDC’s National Center for Immunization and Respiratory Diseases, said in a statement, urging anyone who is unvaccinated to get vaccinated.

In July of this year, an unvaccinated 20-year-old man in New York’s Rockland County was diagnosed with polio and paralyzed by the virus. Since then, polio has been identified in wastewater samples in neighboring counties.

Genetic sequencing has connected the paralyzed man’s case and wastewater specimens from New York to wastewater samples in Jerusalem, Israel, and London, indicating community transmission, according to the CDC.

Every one case of paralytic polio likely represents hundreds of additional infections presenting with flu-like symptoms or no symptoms at all, experts say.

Last week New York Gov. Kathy Hochul issued an executive order declaring a state disaster emergency as a result of the polio outbreak, in an effort to expand vaccination efforts and surveillance.

Unwitting vaccination, infection

Until recently, there had been no cases of the sometimes disabling, occasionally deadly virus reported in the U.S. since 1979. 

The Pan American Health Organization declared it eradicated from the Americas in 1994. But other countries like India and Sudan have continued to struggle with outbreaks of the virus, of which there are multiple types.

Eradicated polioviruses are not returning. Instead, the bodies of those vaccinated outside the U.S. with live, attenuated vaccines rarely—but sometimes—mutate inactivated virus into an activated one. 

That virus can be excreted through the GI tract. In this way, the vaccinated can unknowingly vaccinate others—or set off the spread of an activated virus, experts say. 

The U.S. stopped using live, attenuated vaccines in 2000.

Transmission of polio is fecal-oral, meaning that someone becomes infected by touching fecal matter (even if particles are so small that they’re not visible) or an object contaminated with it, then touching their mouth. The virus can transmit via food or water handled in unsanitary conditions. More rarely, droplets from a sneeze or cough of someone who has polio can infect someone else, according to the CDC.

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