New York Reports First Polio Case in a Decade—Here’s What You Need to Know
An unvaccinated man from New York recently contracted polio.
This is the first documented case of polio in the U.S. since 2013.
Polio is a viral illness that can cause neurological symptoms, such as paralysis.
Yesterday, a case of polio was identified in an unvaccinated adult man in Rockland County, New York.
The New York State Department of Health and its Rockland County counterpart confirmed that the infected person was unvaccinated, and contracted the virus from someone who traveled outside the U.S. and had received the oral polio vaccine, which is a live vaccine that has not been administered in the United States since 2000.
“It’s important to realize that this is not wild polio in NY—but vaccine-derived polio from an oral poliovirus vaccine,” says Amesh Adalja M.D., infectious disease expert and senior scholar from Johns Hopkins Center for Health Security. This means the virus was transmitted to a person vaccinated with the oral polio vaccine, and then reverted to the live virus and spread.
The World Health Organization aimed to eradicate the virus in the 1980s, thanks to vaccines, says William Schaffner, M.D., Professor of Infectious Diseases at the Vanderbilt University Medical Center. But there are still places in the world where polio still exists, particularly in Pakistan and Afghanistan—developing countries where there is political turmoil and a lack of vaccine access. Poliovirus is a dangerous virus that should be taken very seriously, but rest assured, there is essentially no risk of this virus for people who have been vaccinated.
Whether you’re unsure if you received the polio vaccine or simply want to know what polio is and how it spreads, we’re breaking down everything you need to know about polio.
What is polio?
According to the CDC, polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus.
Dr. Schaffner explains that poliovirus “lives in the intestinal tract, and therefore it can spread readily from person to person. Every once in a while, this poliovirus leaves the intestinal tract, gets into the bloodstream, circulates throughout the body, but hones in on [motor] cells in our spinal cord, infects those cells, and destroys them. These motor cells control the movement of our muscles and send signals to our muscles to move. If they are destroyed, it results in paralysis, which can be life-threatening or leave people with a lifetime of disabilities.”
Dr. Adalja adds that “polio is a viral illness spread from person to person that, in most cases, causes no symptoms.” The virus can, however, impact the spinal cord and cause paralysis in about 0.1% of cases, which doesn’t seem likely, but that’s still enough to cause concern.
What are the symptoms of polio?
In unvaccinated people, “90% of polio cases are asymptomatic. 10% or so develop a mild viral illness with fever, malaise, etc. 1-5% may get an aseptic meningitis with headache, neck stiffness, etc. 0.1% can develop paralysis, usually of one limb. Thinking of a 1 out of 1000 risk of paralysis, you can imagine how common polio was in the early 1900s given how many stories you hear of polio paralysis,” says David J. Cennimo, M.D., Associate Professor of Medicine & Pediatrics at Rutgers New Jersey Medical School.
According to the CDC, most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms.
About 1 out of 4 people (or 25 out of 100) with poliovirus infection will have flu-like symptoms that may include:
Fever
Tiredness
Nausea
Headache
Stomach pain
These symptoms usually last two to five days, then go away on their own.
A smaller portion of people (much less than 1 out of 100, or 1 to 5 out of 1000) with poliovirus infection will develop other, more serious symptoms and conditions that affect the brain and spinal cord:
Paresthesia (feeling of pins and needles in the legs)
Meningitis (infection of the covering of the spinal cord and/or brain) occurs in about 1 out of 25 people with poliovirus infection
Paralysis (can’t move parts of the body) or weakness in the arms, legs, or both, occurs in about 1 out of 200 people with poliovirus infection
How does polio spread?
As for how polio is transmitted, it “is a viral illness transmitted by the oral-fecal route that can cause neurological symptoms, such as paralysis”, says Richard Watkins, M.D., an infectious disease physician and a professor of internal medicine at the Northeast Ohio Medical University. So, polio spreads from person to person via the fecal-oral route, explains Dr. Adalja. Fecal-oral transmission happens when an infected person’s contaminated feces enter the body of another person—which often occurs via hands that aren’t washed properly after using the bathroom and anything touched afterward. Eating foods that were washed or harvested from contaminated water can also spread disease in a similar manner.
Dr. Cennimo explains that “polio is an enterovirus [a group of viruses that cause a number of infectious illnesses] that has a particular affinity for neurons (neurotropims) that can lead to paralysis. Enteroviruses are common… and are frequently transmitted from fecal-oral contamination. Polio can be found in wastewater because, as an enterovirus, it is shed in feces.”
It’s important to remember that the vaccine-derived strain of polio can circulate among people who received the oral polio vaccine, so that itself is another way the virus can spread, according to Dr. Watkins.
Dr. Watkins recalls that “famously, President Franklin D. Roosevelt got polio after swimming.”
Is the polio vaccine still given?
The short answer: yes. There are two types of polio vaccines, an oral vaccine that contains live virus, and an injection that contains dead vaccine, according to Dr. Watkins.
According to the CDC, two doses of inactivated polio vaccine (IPV) are 90% effective or more against polio; three doses are 99% to 100% effective. In a study that estimated the efficacy of the oral polio vaccine (OPV) still being used in Afghanistan, the most recent efficacy was shown to be about 96%.
Oral polio vaccine (OPV)
The oral vaccine is a tamed poliovirus, processed so that the virus is benign, which cannot cause paralysis but can signal our immune system, according to Dr. Schaffner. “If I’ve been given the vaccine, which has a live virus, it goes down in my colon, it’s still alive, and if I have close contact with you, I can transmit that vaccine virus to you, so you are getting protected also,” he explains. The problem is “rarely, one in about 3 million doses, this tamed virus can mutate and revert back to being a bad virus which can create polio paralytic disease.”
In the U.S. today, we use an inactivated polio vaccine as an injection, explains Dr. Cennimo, which mitigates the risk of spreading the live virus.
“Prior to 2000 in the U.S. and ongoing in parts of the world, polio was a live attenuated virus as an oral vaccine (drops on a sugar cube stories from your parents/grandparents). The vaccine virus can replicate and generates great immunity. However, it is also possible for the vaccinated person to shed virus for a period of time in stool (up to 8 weeks). In rare cases, the virus can become stronger and more virulent when shed and infect others who are susceptible. The risk of this is why the U.S. moved away from using oral polio vaccine in 2000.”
Injectable polio vaccine (IPV)
“This vaccine is highly effective and is not live. It is not capable of causing infection,” explains Dr. Schaffner. Dr. Watkins adds that “there is no way to get polio from the injectable vaccine. The oral vaccine hasn’t been used in the U.S. since around 2000, but it is still used in other countries. The CDC recommends that children get four doses of the polio vaccine. They should get one dose at each of the following ages: 2 months old, 4 months old, 6 through 18 months old, and 4 through 6 years old.”
Should I be worried about polio?
Not if you’re vaccinated. As long as you are vaccinated against polio, whether you received the injectable or oral vaccine as a child, you are protected.
What can you do to prevent polio?
“Vaccination is the best prevention measure for polio,” says Dr. Adalja.“Get the polio vaccine series,” says Dr. Cennimo. “Get vaccinated if you aren't,” says Dr. Watkins.
Get the idea?
The best way to protect yourself from the poliovirus is to get vaccinated if you aren’t already. If you are, then there really is no reason to panic. Another deadly virus resurfacing in the news is triggering for many of us, but as long as you’re vaccinated, you’re protected.
What to do if you think you have polio
If you have symptoms of polio, contact a healthcare provider. The healthcare provider will ask you about your symptoms and whether you have traveled recently.
Because polio symptoms look a lot like flu symptoms, the healthcare provider may order tests to rule out more common viral conditions.
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