What is Polio?

Polio (also known as Poliomyelitis)

An infectious disease that can be transmitted from person to person. Polio is caused by poliovirus, an enterovirus. Poliovirus is most well known for causing paralysis in young children.[0]

Poliovirus is part of the picornavirus viral family, a taxonomic grouping that includes other familiar viruses such as the rhino virus and hepatitis A virus. These viruses are most known for their icosahedral capsid(20 faces) structure that lacks a viral envelope and carries the positive-sense single stranded RNA genome. Further characteristics include being able to withstand low pH and thus able to pass through the stomach to infect and replicate in the intestinal epithelial cells and being incredibly infectious through the fecal-oral route. [0]

*funfact: Humans are the only natural hosts of this disease. Chimapanzees, Green African Monkeys etc can only be experimentally infected.

Whilst most infections are asymptomatic, viral particles that gain entrance into the central nervous system can replicate in neurons and destroy cells that govern muscle function resulting in flaccid paralysis.[0] To simply put it, the poliovirus invades the brain and spinal cord and may cause paralysis. However, 72 out of 100 infected people will not have any visible symptoms.[1]

Symptoms commonly include:
-Sore throat
-Fever
-Feeling lethargic
-Nausea
-Headache
-Stomach pains

More severe symptoms include:
-Paresthesia ( pins and needles in arms and legs or both)
-Meningitis (Inflammation of the brain & spinal cord)
-Paralysis or weakness of arms and legs

*Paralysis may be fatal due to the inactivation of muscles that aid in respiration. Hence Polio is often referred as a paralytic infection.

Poliovirus is easily transmitted through contact with an infected person. The virus lives in the infected person's throat and intestine. It enters the body though contact of feces and though less common, sneezes and coughs. Contamination of everyday items after not properly washing after using the toilet may speed up the infection rate. This is especially so in rural countries living in unsanitary conditions.

*The poliovirus may be cured with Oral Poliovirus Vaccine(OPV) or Inactivated Poliovirus Vaccine(IPV) but there are cases of Post-polio syndrome where patients recover after a vaccination but there happened to be a relapse of the patient's previous condition. [1]

Reference:
[0]Poliomyelitis. (n.d.). Retrieved July 31, 2015, from https://microbewiki.kenyon.edu/index.php/Poliomyelitis
[1] What Is Polio? (2014, October 15). Retrieved July 31, 2015, from http://www.cdc.gov/polio/about/

How relative is Polio today?

As shown in the video, Polio has mostly been eradicated with the exception of 3 main countries

-Afghanistan
-Nigeria
-Pakistan

This however does not mean that countries other than the above mentioned 3 cannot be affected by the poliovirus. WHO recommends all those travelling to previously affected countries to be properly immunized before proceeding to that region.


The up to date 14 January 2015 data sheet depicts that in the year 2014, there was a total of 350 documented cases globally. Of the 350 cases, 331 of those cases were in these 3 endemic countries. This shows that Polio is infectious, and that we should not be complacent in our vaccinations since Polio is also documented in non-endemic areas. 

*endemic: (disease or condition) associated in a particular area. 

The current issue in the 3 countries mentioned above is that the cases documented were mostly caused by wild poliovirus type 1. Documented cases show that Nigeria and Afghanistan have mostly contained the situation but Pakistan remains as the top location of which most Polio cases are documented.  Below is a statistic guide of the cases documented in the 3 countries. [6]

Reference:
[6]Wild Poliovirus (WPV) cases week Ending 14 January 2015. (2015, January 14). Retrieved May 26, 2015, from http://clubrunner.blob.core.windows.net/00000050024/en-ca/files/sitepage/polio-headlines/14-jan-2015/Polio-Headlines-Jan-14.pdf

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