By Richard Sternberg
First COVID-19. Then monkeypox. Now polio. Next, West Nile Virus. And always in the background in Central New York, Lyme disease. The pan-, epi-, and endemics of deadly and disabling diseases doesn’t seem to stop. This week I will try to tackle polio.
There are very few people who will read this that remember how much polio terrorized people, especially mothers, in the first half of the 20th century. People become sick, develop muscle paralysis, develop severe weakness, and occasionally have respiratory muscle involvement, which could lead to the use of mechanical ventilation including, by what was called, an iron lung, and ultimately lead to death.
I myself remember my mother’s concerns and fears that I did not understand at the time. I had the misfortune of having to see an iron lung in use when I was a medical student, though for a different disease. It’s horrible to think of a person having to try and live their life in such a device. Truthfully that wasn’t much of a life at all.
Poliomyelitis, generally known as polio, is an infectious disease caused by a virus. The name comes from ancient Greek. Polios means grey, myelos means marrow and together this refers to the grey matter of the spinal cord. Itis denotes inflammation. That is inflammation of the spinal cord’s gray matter though this can extend to the brain and cause polioencephalitis.
On July 18, 2022, the New York State Department of Health notified the Centers for Disease Control of the detection of polio virus type 2 in stool specimens from an unvaccinated, immunocompetent, young adult from Rockland County New York who had developed acute flaccid myelitis (AFM). This means that some or many of the patient’s muscles had rapidly developed weakness.
The patient was hospitalized and on days 11 and 12 after admission Vaccine-derived poliovirus type 2 (VDPV2) was found in the patient’s stool. As of August 22, VDPV2 has been found in the wastewater of Rockland County, Orange County, and New York City.
Water samples that had previously been tested for COVID-19 were retested for poliovirus which was found in specimens up to 25 days before the patient’s symptoms began and after 41 days after the patient’s symptoms onset.
This indicated that there had to be other individuals who were VDPV2 positive in the region.
The last case of polio caused by the wild strain in the United States occurred in 1979. The previous cases of any type of polio in the United States have been in 2005, which was a type VDPV type 1. The current case in wastewater indicates the need to maintain high vaccination rates of the type of polio vaccine used in the United States. Since 2000 all vaccinations for polio in the United States have been of the injectable, Inactive Polio Virus type. The oral type of vaccine has been associated with the current outbreak of infection.
Polio only occurs in humans and spreads either through fecal to oral transmission or oral to oral transmission. One might be surprised how much fecal matter there is that contaminates many other things especially through water and through poor hygiene. Swimming pools were thought to be a place of high risk of developing polio back in the mid-20th century and earlier and of course this makes sense because the possibility of contamination of the water from other bathers.
Interestingly polio symptoms are either rare or minor.
In children it is estimated that 72% of the cases have no symptoms whatsoever, 24% have minor illness which could easily be mistaken for another viral disease. 1 to 5% have a non-paralytic form of meningitis which is generally self-limiting. Only 0.1 to 0.5% of cases have paralytic poliomyelitis. Approximately 79% of these are spinal polio, 19% are bulbospinal which means it involves both the brain and the spinal cord, and 2% are bulbar polio which affects the brain.
In most people with a normal immune system, the virus is asymptomatic and in only about 1% of cases does the virus migrate from the gastrointestinal tract by which it enters the body into the nervous system.
The reason there were apparently so many cases of polio that were highly noticeable in the general population was because the disease is rapidly and easily transmitted and was widely spread. If a high enough percentage of the population, say 10% in 1950, were positive for polio in the United States this would’ve led to approximately 100,000 people that demonstrated some or severe paralysis.
It is no wonder that the disease scared mothers because it was generally visible in many communities.
There are three types of polioviruses, type 1, type 2 and type 3. Each are slightly different in the proteins of their capsule. The most common is polio virus type 1. Individuals who are exposed to polio either through infection or immunization develop immunity.
The disease is transmitted primarily by ingesting contaminated food or water. It is occasionally transmitted by direct oral to oral methods. It is most infectious 7 to 10 days before and after the appearance of symptoms but transmission is possible as long as the virus remains in the feces or saliva. Immune deficiency, malnutrition skeletal muscle injury and pregnancy increase the risk of infection.
Polio virus enters through the mouth, and binds to the tissues it comes in contact with ending up in the pharynx and intestinal mucosa. Rarely does it progress to the nervous system. Involvement of the nervous system is not necessary for the virus’s reproduction.
1% of infections involve the motor neurons i.e., nerve fibers that control muscles, within the spinal cord, brain stem, or motor cortex of the brain. This is what leads to the paralytic poliomyelitis.
Early symptoms of paralytic polio include high fever, headache, stiffness in the back and neck, weakness of muscles, difficulty swallowing, muscle pain, loss of reflexes and others. Paralysis rates vary with the type of polio.
The diagnosis of paralytic polio is made based on finding poliovirus from a stool sample or swab of the pharynx. Of course, one must be clinically suspicious of the disease. It is be very rare to think of polio except in the paralytic cases or except during epidemics.
There are two types of polio, the wild type, which is encountered in nature, and the OPVD which is derived from a strain of attenuated poliovirus that is used in the production of oral polio vaccine. This is the basis of the case recently in New York State.
This is the reason only inactivated polio virus vaccine is used in the United States. Inactivated vaccine has to be injected to get into the body while the attenuated or weekend viral vaccines enter through the oropharyngeal or gastrointestinal route. It supposed to be a form of the virus that doesn’t cause the disease.
Unfortunately, in rare cases the oral attenuated virus mutates into an infectious type. This type then causes symptoms and causes paralysis and becomes transmissible. The patient in New York was unvaccinated and had not recently been out of the country but had been at a large gathering at which people who had recently been in the Middle East where OPVD is used.
Therefore, the presumed mechanism of infection was from somebody vaccinated outside the United States who developed an active form of polio and transmitted it to others.
Since paralysis is seen only in about one in 500 to 1,000 of infected people, this suggests a large number of people in the community were actually infected with a form that could reproduce and cause symptoms.
There is no cure for polio. Treatment consists of relief of symptoms and preventing complications and includes antibiotics to prevent infections, analgesics for pain, and moderate exercise and nutrition. It frequently requires long-term rehabilitation.
The patient noted above is currently in a rehab hospital. Ventilators may be required to support breathing. Historically an iron lung in which a patient was placed to force air into the lungs by developing negative pressure in the device was used. Today most polio patients who need respiratory support either have a ventilator or a jacket-type device that can also cause negative pressure in the pulmonary cavity.
Some patients with short-term symptoms can recover but if the spinal motor nerve cells are destroyed, loss of function is permanent. In some cases, some return of function is possible but rarely is it complete. Orthotics or devices such as braces or shoe adaptations may also be used.
Two years ago, there were only a total of 78 cases of wild polio in the world and 365 cases of oral vaccine derived poliomyelitis. The number of cases in the United States will probably increase significantly because of transmission to people who have not been vaccinated and to more extensive testing that will be done to people with non-paralytic symptoms.
According to the New York State Immunization Information System, proper polio vaccination coverage among infant children living in Rockland County was 67% in July 2020 and only 60.3% in August 2022 with certain areas of the county having coverage as low as 37.3%. This compares to the national average of 92.7%. Much of the decrease from 2020 to 2022 was due to COVID related fears.
The low vaccination rate in that area obviously contributes to the disease. Polio was such a scourge and is so simple to prevent with lifelong immunity obtained through vaccination with inactivated virus vaccine.
If you don’t know your vaccination status try and find it out especially if you’re going to go into an area with known disease, and if negative get vaccinated first.