Affecting children under 5 most strongly, the worst form of the virus causes nerve damage that can lead to paralysis, difficulty breathing and death. During the epidemics of the 20th century, the virus often affected the warm summer months, ravaging towns and cities every year or so.
Polio was one of the most feared diseases in the world until Dr. Jonas Salk invented the polio vaccine and tested its safety in 1954.
“In the early 1950s, before polio vaccines were available, polio outbreaks caused more than 15,000 cases of paralysis each year” in the United States, the Centers for Disease Control and Prevention noted. of the USA. “Parents were afraid to let their children go outside, especially in the summer when the virus seemed to be at its peak.”
What causes polio?
An enterovirus called poliovirus causes poliomyelitis. There are three strains, two of which have been eliminated in the world, according to the Global Polio Eradication Initiative, a WHO program.
However, a wild type of polio virus still circulates in Pakistan and Afghanistan and can be picked up by travelers and carried around the world. “It only takes one traveler with polio to bring the disease into the United States,” the CDC said.
Transmission can also occur when there are not enough vaccinated children in an area. This typically happens with the oral polio vaccine, created by Dr. Albert Sabin and first used in 1961. The formulation of this vaccine has a mixture of each of the three types of live attenuated poliovirus strains, according to GPEI.
“Weakened strains are shed by vaccinated children into the environment through their digestive systems and can be passed from one unvaccinated individual to another, a process exacerbated by poor sanitation systems and the absence of clean water,” he said. say the GPEI.
Once the strain has infected an unvaccinated person, it begins to circulate and can be transported through travel around the world.
That may be a factor in the recent diagnosis of polio in a man in Rockland County, New York, the first case of polio in the United States since 2013, according to the New York State Department of Health. Tests confirmed by the CDC found a type of virus that would have come from someone who had received “oral polio vaccine (OPV), which is no longer licensed or administered in the US,” the health department said in a communicated
“This suggests that the virus may have originated at a site outside the United States where OPV is administered, as (reverted) strains cannot arise from inactivated vaccines,” the statement said.
Health professionals around the world routinely use different types of oral vaccines to fight polio, because they are inexpensive, easy to administer, safe, effective, and provide long-lasting protection. However, Salk’s original, inactivated polio vaccine, given through a series of vaccinations during childhood, has been the only version used in the US since 2000, according to the CDC.
Polio is highly contagious
The polio virus lives in the throat and intestines of an infected person. People who carry poliovirus, including those without symptoms, can spread the highly contagious virus for weeks in their stool. In rare cases, viral transmission can occur through droplets from a sneeze or cough, the CDC said.
Most people come into contact with polio by picking up a small piece of infected poop and then touching their mouth. Exposure to the virus also occurs when children swallow toys or other objects contaminated with feces.
In unsanitary conditions, the virus can also spread through contaminated food and water.
The symptoms of polio start like the flu
Like Covid-19, many cases of polio are asymptomatic. In fact, people have no symptoms in about 95 percent of all polio cases, the CDC said.
When symptoms appear, they can take three forms. Flu-like symptoms such as headache, sore throat, nausea, diarrhea, fever, and fatigue are characteristic of abortive poliomyelitis.
If these symptoms include additional neurological symptoms, such as sensitivity to light or neck stiffness, the person may have nonparalytic poliomyelitis.
The most dangerous version of polio can cause paralysis in “a few hours”, the WHO said. The illness begins with flu-like symptoms, then progresses to muscle pains or spasms and loss of reflexes. Paralysis may follow on one side or the other.
The disease can also affect the lungs: 5% to 10% of people die when their breathing muscles become immobilized, according to the WHO. During the epidemics of the 1940s and 1950s, patients were often placed in an iron lung to help them breathe. However, statistics have shown that in most cases of paralytic polio, the person recovers: less than 1 percent of people who contract polio become paralyzed, according to GPEI. Unfortunately, muscle or joint weakness and pain, breathing and swallowing problems, sleep problems, and cold intolerance can remain lifelong in some cases. The virus can even hide, lie dormant, and resurface years later in what’s called post-polio syndrome, the CDC said.
Treatment for poliomyelitis
There is no cure for polio, only treatment to relieve symptoms.
“Heat and physical therapy (are used) to stimulate the muscles and antispasmodic drugs are given to relax them,” the GPEI said. “While this can improve mobility, it cannot reverse the permanent paralysis of polio.”
Vaccination is the only prevention.