Poliomyelitis
By: Isabel Perez
Background Information
Poliomyelitis is an infectious viral disease that affects the central nervous system and can cause temporary or permanent paralysis. Its name comes from the Greek words for grey and marrow, referring to the spinal cord, and the suffix –itis, meaning inflammation. The disease became prevalent in the 20th century, but there have been many cases prior to that time period. The Egyptian stone carving from 1403-1365 BC to the right depicts a man with a walking stick and deformed foot, both of which suggest he had polio. Therefore, it is believed that polio has existed as long as human society. The first large polio epidemic took place in 1916. Nationwide, there were 27,000 cases and 6,000 deaths. Children were particularly affected during this outbreak, and polio was nicknamed “infantile paralysis.” The 20th century saw a few other major outbreaks, including one in 1952 that had a record of 57,628 cases. Polio’s history of infecting mainly children has led people today to the misconception that it only infects children. In actuality, it can infect adults as well. Another misconception about polio is that it is always paralytic. However, about 95% of all polio cases experience no symptoms at all.
Immune System Response
Polio is a highly infectious illness that spreads through contact between people, by nasal and oral secretions, and by contact with contaminated feces. It enters the body through the mouth. Then, it infects the host’s cells and begins to replicate in the throat and gastrointestinal tract. The virus rapidly divides in the intestines for a week before spreading to other areas of the body. Eventually, it moves into the bloodstream where it is carried to the central nervous system. It replicates and destroys motor neuron cells, which control the muscles for swallowing, circulation, respiration, and movement of the torso, arms, and legs.
The human immune system fights off polio by producing antibodies that engage the protein covering of the virus, preventing it from interacting with other cells so that it cannot replicate. This is the only way that the body can work to fight off the pathogen. If the host has a weak immune system, the pathogen is likely to spread and worsen. A host with a strong immune system is likely to kill the pathogen.
There are two vaccines available to fight polio: inactivated polio virus (IPV) and oral polio vaccine (OPV). IPV is a series of injections that start two months after birth and continue until the child is 4-6 years old. This vaccine is provided to most children in the U.S. It is made from inactive poliovirus but is very safe and effective and cannot cause polio. OPV is created from a weakened form of poliovirus. This is the vaccine of choice in many countries because it is cheap, easy to administer, and gives an excellent level of immunity. Its advantage over IPV is that once children are immunized, they can pass the weakened virus to others who have not received the vaccine. This contact with the virus gives unvaccinated children immunity as if they have been vaccinated. However, in rare cases, it reverts to a dangerous form of poliovirus that is able to paralyze the patient or others who have had close contact with them.
Containment Plan
The poliovirus is specific to humans. It usually enters the environment in the feces of someone who is infected. Areas with poor sanitation allow the virus to easily spread from feces into the water supply. Individuals who carry the poliovirus can spread it via their feces for weeks, even if they have shown no symptoms of having it.
The most common way that polio outbreaks have been dealt with in the past was by vaccinating people against the disease. After history’s worst polio epidemic in 1952, Dr. Jonas Salk developed the first safe and effective polio vaccine in 1955. In the two years before the vaccine was widely available, the average number of polio cases in the U.S. was more than 45,000. By 1962, that number had dropped to 910. Vaccination proved to be a successful way of containing the disease, but because people no longer get vaccinated for it, bringing back the vaccine during an outbreak could make it worse by infecting the scientists who make it. Therefore, we would have to go about containment a different way.
I believe the best way to contain the virus during an outbreak today would be to break the “environment” side of the Epidemiological Triangle by improving the water sanitation in areas where it is poor. To do this, we would need to implement new standards for the cleanliness of our water and come up with ways to better sanitize areas of water that don’t meet the standard. This would greatly lessen the spread of the disease from feces into people’s water because the virus would be taken out of the water during filtration. Because polio has no cure, those infected would have to be confined so that they cannot transmit the virus to others. In breaking the “environment” side of the triangle, polio would have a much lesser chance of infecting humans and would therefore vanish over time.
My plan is very different from previous outbreak containment plans. Previous plans broke the “agent” side of the Epidemiological Triangle by vaccinating people against the poliovirus, such as after the epidemic of 1952. My plan is to eliminate polio-friendly environments so that it becomes difficult for people to spread the disease to one another. If an outbreak were to persist, I predict that it would be very difficult to get under control because people who don’t show symptoms of having the virus, which would be the majority, would unknowingly give it to others. This would cause the number of people who have it to grow exponentially, and without a cure, the virus would stick around for years.
Sources
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"History of Polio ( Poliomyelitis )." History of Vaccines. N.p., 10 Mar. 2016. Web. 18 Jan. 2017.
"History of Polio." BBC News. BBC, 25 Sept. 2015. Web. 18 Jan. 2017.
"How the Poliovirus Works." NMAH. N.p., n.d. Web. 18 Jan. 2017.
"Polio." Human Diseases and Conditions. N.p., n.d. Web. 18 Jan. 2017.