The first U.S. case of polio in nearly a decade has been confirmed in an unvaccinated individual in Rockland County, N.Y., local and state health officials announced Thursday.
The patient has since been discharged and living at his parents’ home with his wife. He is able to stand, but is having difficulty walking, the official said.
Rockland County and New York State health officials Thursday alerted clinicians to be vigilant for additional cases. Asked about the possibility of more polio cases emerging locally, Rockland County Health Commissioner Patricia Schnabel Ruppert said at a news conference, “We only have the one case. Let’s hope that’s all we find.”
Rockland County Executive Ed Day said the patient who is infected is not contagious.
“Right now, the risk to the vaccinated public is low, but experts are working to understand how and where this individual was infected,” the Centers for Disease Control and Prevention said in a statement.
Officials did not elaborate on why the patient is no longer contagious. But he sought treatment at a hospital in New York City around June 20, the official said. Patients are most contagious during the first two weeks of illness, said Thomas Giordano, chief of infectious diseases at Baylor College of Medicine.
Polio is a very contagious, life-threatening viral disease that causes permanent paralysis in people who are not fully vaccinated in about 5 out of every 1,000 cases. Most of the U.S. population has protection against the disease because they were vaccinated during childhood. But in areas with low vaccination coverage, such as the ultra-Orthodox Jewish community in Rockland County, people who are not vaccinated are at high risk. There is no treatment for polio, but vaccination prevents the disease.
Due to the success of a national vaccination program after the vaccine was introduced in 1955, polio cases were cut dramatically. The last naturally occurring cases in the United States were recorded in 1979.
While still rare, more-recent polio infections in the United States were imported through travel or contact with someone who had received oral polio vaccine in another country. The last known U.S. case was recorded by the CDC in 2013.
The virus typically enters the body through the mouth, usually from hands contaminated with the fecal matter of an infected person. Respiratory transmission and oral-to-oral transmission through saliva may also account for some cases.
Up to 95 percent of people infected with polio have no symptoms but can still be contagious. About 4 to 5 percent of infected people have minor symptoms such as fever, muscle weakness, headache, nausea, and vomiting. Symptoms can take up to 30 days to appear. One to 2 percent of infected people develop severe muscle pain and stiffness in the neck and back. Less than 1 percent of polio infections result in paralysis.
The Rockland County man lives in a community that has historically been under-vaccinated and was the epicenter of the measles outbreak in 2019, according to public health officials who spoke on the condition on anonymity.
In this case, genetic sequencing performed by the Wadsworth Center — New York state’s public health laboratory — and confirmed by the CDC, showed a type of polio virus that indicates transmission from someone who received the oral polio vaccine, according to Thursday’s alert.
There are two types of vaccine that can prevent polio. Inactivated poliovirus vaccine, or IPV, is given as an injection in the leg or arm, depending on the patient’s age. Only IPV has been used in the United States since 2000.
Oral poliovirus vaccine, or OPV, is still used throughout much of the world. OPV is no longer authorized or administered in the United States because of its potential to cause vaccine-derived poliovirus. This case suggests that the virus may have originated in a location where the oral vaccine is administered, outside the United States, the alert from New York state and Rockland County said.
Wild-type polio is the naturally occurring form of the virus. However, some people can become infected from a weakened strain of the virus that was used to make the oral polio vaccine early on. Most countries, including the United States, immunize children using a vaccine made from a form of the virus that is no longer alive.
Vaccine-derived polio can emerge if the weakened live virus contained in OPV, shed by vaccinated children, is allowed to circulate in under-immunized populations for long enough to genetically revert to a version that causes paralysis, the CDC said in its statement. Cases of vaccine-derived polio “are not caused by a child receiving the polio vaccine.”
“Many of you may be too young to remember polio, but when I was growing up, this disease struck fear in families, including my own,” Day said in a statement. “The fact that it is still around decades after the vaccine was created shows you just how relentless it is. Do the right thing for your child and the greater good of your community and have your child vaccinated now.”
The coronavirus pandemic has resulted in a drop in routine immunization rates, according to recent reports. Nearly 400,000 fewer children entered kindergarten in the United States during the last school year because of pandemic-related disruptions, raising concerns that no one knows how many kids received childhood vaccinations for common diseases, according to federal health data released this spring. All states require childhood vaccinations for illnesses such as polio, measles and whooping cough.
Day lamented the decline in global vaccination rates Thursday, warning: “Ladies and gentlemen, we’re playing with fire.”
Polio is endemic in Afghanistan and Pakistan, although numerous countries in Africa, the Middle East and Asia have also reported cases in recent years. In June, the United Kingdom Health Security Agency reported finding poliovirus in sewage samples collected from the largest treatment plant in the United Kingdom, the first time a likely outbreak has been identified in London. But so far, no cases have been detected.