Before the polio vaccine became available in the 1950s, people wary of the disabling disease were afraid to let their children go to school. As polio resurfaces decades after it was eradicated in the U.S., Americans unfamiliar with the dreaded disease need a primer on protecting themselves and their young children — many of whom are vulnerable to the COVID-19 pandemic. Emerging from shock.
What is poliomyelitis?
Polio is short for “poliomyelitis,” a neurological disease caused by infection with the poliovirus. Of the three types of wild poliovirus – serotypes 1, 2 and 3 – serotype 1 is the most virulent and most likely to cause paralysis.
Most people infected with the poliovirus do not get sick and have no symptoms. Up to a quarter of those affected may experience mild symptoms such as fatigue, fever, headache, neck stiffness, sore throat, nausea, vomiting and abdominal pain. So, as with Covid-19, people who don’t have symptoms can unknowingly spread it by interacting with others. But in 1 in 200 people with poliovirus infection, the virus can attack the spinal cord and brain. When it affects the spine, people may develop muscle weakness or paralysis, including in the legs, arms, or chest wall. The poliovirus can also affect the brain, causing difficulty breathing or swallowing.
People can develop post-polio syndrome decades after infection. Symptoms may include muscle pain, weakness, and wasting.
People with poliomyelitis may be confined to a wheelchair for life or unable to breathe without the help of a ventilator.
How is polio spread?
The virus that causes polio is spread through the “oral-fecal route,” which means it enters the body through the mouth through hands, water, food, or other items contaminated with feces containing the poliovirus. Rarely, the poliovirus can be spread through saliva and upper respiratory droplets. The virus then infects the throat and stomach, spreads to the bloodstream and attacks the nervous system.
How do doctors diagnose polio?
Poliomyelitis is diagnosed through patient interviews, physical examination, laboratory testing, and scans of the spine or brain. Health care providers can send stool, throat swabs, spinal cord and other samples for laboratory testing. But because polio has been rare and extinct in the United States for decades, doctors may not consider diagnosing symptomatic patients. And tests for suspected polio should be sent to the Centers for Disease Control and Prevention, since even academic centers no longer test.
How can transmission of poliovirus be prevented?
The CDC recommends that all children receive the polio vaccine at 2 months, 4 months, 6 to 18 months, and 4 to 6 years of age, for a total of four doses. All 50 states and the District of Columbia require that children attending daycare or public school be vaccinated against polio, but some states allow medical, religious, or personal exemptions. The Vaccines for Children program provides free polio vaccine to children who are Medicaid-eligible, uninsured, or underinsured, or who are American Indian or Alaska Native. Most people born in the United States after 1955 have likely received the polio vaccine. But vaccination rates are alarmingly low in some areas, such as New York’s Rockland County, where it’s 60%, and Yates County, where it’s 54%, because many families there claim religious exemptions.
There are two types of polio vaccine: killed, inactivated polio vaccine (IPV) and attenuated, live, oral polio vaccine (OPV). IPV is an injectable vaccine. OPV can be given by mouth or by drops on a sugar cube, so it is easy to administer. Both vaccines are highly effective against paralytic polio, but OPV appears to be more effective in preventing infection and transmission.
Both wild poliovirus and live, weakened OPV virus can cause infection. Because IPV is a killed virus vaccine, it cannot infect or replicate, give rise to vaccine-derived poliovirus, or cause paralytic poliomyelitis disease. Weakened, OPV viruses can mutate and regain their ability to cause paralysis – known as vaccine-acquired poliomyelitis.
Since 2000, only IPV has been given in the United States. Two doses of IPV are at least 90% effective and three doses of IPV are at least 99% effective in preventing paralytic poliomyelitis. The United States stopped using OPV because of a 1-in-2,000 risk of stroke in unvaccinated individuals receiving OPV. Some countries still use OPV.
Vaccination against polio began in the United States in 1955. Cases of paralytic poliomyelitis declined from 15,000 cases per year in the early 1950s to less than 100 in the 1960s and then less than 10 in the 1970s. Today, poliovirus is most likely to spread where sanitation and hygiene are poor and vaccination rates are low.
Why is polio spreading again?
The World Health Organization declared North and South America polio-free until 1994, but in June 2022, a young adult living in Rockland County, New York was diagnosed with serotype 2 vaccine-derived poliovirus. The patient complained of fever, neck stiffness and leg weakness. The patient had not recently traveled outside the country and was likely infected in the United States. The CDC has since begun monitoring wastewater for poliovirus. Polioviruses genetically linked to the Rockland County case have been detected in wastewater samples from Rockland, Orange and Sullivan counties, indicating a community-wide outbreak as of May 2022. An unrelated vaccine-derived poliovirus has also been detected in New York City sewage.
How do I know if I have been vaccinated against polio?
There is no national database of immunization records, but all 50 states and the District of Columbia have immunization information systems with records dating back to the 1990s. Your state or local health department may also have records of your vaccinations. People immunized in Arizona, the District of Columbia, Louisiana, Maryland, Mississippi, North Dakota, and Washington can access their immunization records using the MyIR mobile app, and those in Idaho, Minnesota , New Jersey, and Utah who have received the vaccine may do so. Using the Docket app
You can also ask your parents, your childhood pediatrician, your current doctor or pharmacist, or the K-12 schools, colleges, or universities that have your vaccination records. Some employers, such as health care systems, may also keep records of your vaccinations in their occupational health office.
There is no test to determine if you are immune to polio.
Do I need a polio vaccine booster if I was fully vaccinated against polio as a child?
All children and unvaccinated adults should complete the four-dose series of polio vaccine recommended by the CDC. If you received OPV, you do not need an IPV booster.
Adults who are immunocompromised, traveling to a country where poliovirus is circulating, or have jobs at increased risk for poliovirus, such as some lab workers and health care workers, should receive a one-time IPV. A booster can be found.
How is polio treated?
People with mild poliovirus infection do not need treatment. Symptoms usually go away on their own within a few days.
There is no cure for paralytic polio. Treatment focuses on physical and occupational therapy to help patients adapt and regain function.
Why is polio virus not eradicated?
Smallpox is the only human virus that has been declared eradicated to date. A disease can be eradicated if it affects only humans, if viral infection produces long-term immunity to reinfection, and if there is an effective vaccine or other prevention. The more contagious a virus is, the harder it is to eradicate. Viruses that spread asymptomatically are also more difficult to eradicate.
In 1988, the World Health Assembly pledged to eradicate polio by the year 2000. Violent conflict, the spread of conspiracy theories, vaccine skepticism, insufficient funding and political commitment, and poor-quality vaccination efforts have slowed progress toward eradication, but before the Covid pandemic, the world Polio is very close to being eradicated. During the pandemic, childhood immunizations, including the polio vaccine, declined in the United States and around the world.
To eradicate polio, the world must eliminate all wild polioviruses and vaccine-derived polioviruses. Wild poliovirus serotypes 2 and 3 have been eradicated. Wild poliovirus serotype 1, the most virulent form, is endemic only to Pakistan and Afghanistan, but vaccine-derived polioviruses continue to circulate in some countries in Africa and other parts of the world. A stepwise approach involving the use of OPV, then a combination of OPV and IPV, and then IPV alone would likely be needed to eradicate polio from the planet.
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