The risk of poliomyelitis infection depends on vaccination

Vaccines have helped neutralize the global threat of polio, a deadly scourge that can cause paralysis and death, but the life-saving drug could cause a resurgence of the virus in the United States and other countries this year.

An oral vaccine that uses a live, weakened version of polio has spread in two suburban New York counties, where health officials believe it caused a virus that infected an unvaccinated young adult and left him partially paralyzed.

“Even a single case of paralysis represents a public health emergency in the United States,” the Centers for Disease Control and Prevention said in a new report on the case Tuesday. A virus since 1979. “This case highlights the risk of paralysis in unvaccinated people.”

Fortunately, those who have received the polio vaccine — which is among the 10 vaccinations required for enrollment in California’s K-12 schools — needn’t worry, medical experts say. The live version of the virus used in the vaccines in question is no longer used in the United States.

“If you’ve been vaccinated, you’re protected. “You have nothing to worry about,” said the doctor. Lee Riley, director of the Department of Infectious Diseases and Vaccinology at the University of California, Berkeley. “This is something people who are unvaccinated should be concerned about.”

The poliomyelitis virus enters the body through the mouth and lives in the food and intestines. It is spread from person to person by coughing or sneezing, or through infected feces. Most people who become infected do not experience any symptoms. One in four will develop flu-like symptoms that disappear after two to five days.

Two similar cases were identified in the UK and Israel. As of August. In 2010, the CDC reported no more cases of polio in the United States

But the CDC said the discovery of the polio virus in sewage from New York’s Rockland and Orange counties “indicates community transmission and the continued risk of polio in unvaccinated individuals.”

It’s unclear how the patient in New York was infected and the virus entered the sewage system, the CDC said. But because he didn’t travel abroad, it “demonstrated a chain of transmission within the United States from someone who received the oral polio vaccine abroad.”

The US stopped providing oral live attenuated polio vaccines for routine immunization in 2000, and they were phased out globally in 2016, according to the CDC. Since then, the U.S. has only used a polio vaccine that contains an inactivated virus that cannot replicate, amplify, or cause disease.

But vaccine-derived polio viruses can also occur when live, attenuated, or “attenuated” versions of the virus are used in oral polio vaccines in areas where vaccination coverage is low, the CDC says.

When the virus multiplies in a recently vaccinated person, “this can cause the virus to become neurovirulent,” the CDC says, resuming its potential as a paralyzing and deadly pathogen. Unvaccinated people exposed to the virus from the vaccine can develop polio.

“It’s going to go back to how it was,” Riley said. “It’s rare to see something like this happen.”

About 1 in 2,000 people who get the infection will lose their hands and feet. One in 10 people can develop paralysis that stops them breathing on their own, and most of them die.

The worst polio epidemic in the US occurred before vaccines in the 1940s, when about 35,000 cases of polio were reported each year. Outbreaks of disease led to quarantines, and many parents were afraid to let their children play outside with other children.

The introduction of polio vaccines in the 1950s dramatically reduced the number of cases, and North and South America were declared polio-free in 1994. The virus was last seen in the United States in 2005 when an Amish baby with a weakened immune system was infected. Hospitalized in Minnesota.

No paralysis occurred and there were no other cases. This is believed to be the first transmission of a vaccine-derived poliovirus in an unvaccinated community in a developed country.

Last month, a young, unvaccinated adult infected in New York City initially presented with fever, neck stiffness, gastrointestinal symptoms, and limb weakness, prompting hospitalization.

Of particular concern to the CDC were the relatively low rates of vaccination in these New York counties. In Rockland County, where the patient lived, the polio vaccination rate dropped from 67% in 2020 to 60% in 2022, and to 37% in some zip codes, compared to the national rate of nearly 93%.

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