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/

Equatorial Guinea update - linked to Cameroon cases

On 16 July 2014, Equatorial Guinea reported a total of 5 cases of wild poliovirus type 1 (WPV1) with the onset of paralysis betwee 28 January 2014 and 3 May 2014. Genetic sequencing had suggested that the cases were linked to the outbreak in Cameroon.

A national emergency action plan to respond to this outbreak was developed and initiated by the Ministry of Health and partner agencies. 3 nationwide campaigns with bivalent oral polio vaccine (bOPV) were conducted in the country with 2 of the 3 campaigns targetting children under the age of 15 in April and May 2014 whilst the other campaign targeted children under the age of 5 in late May.
On July 2014, the country had planned and initiated bOPV to be given to all of its citizens whilst another campaign for bOPV will be conducted on August 2014 for children under the age of 15.

The Disease Outbreak News update published on 25 June 2014, reported Brazil on 18 June 2014 confirmed that there was WPV1 detected in a sewage sample collected at the Viracopos International Airport in March 2014, with genetic sequencing similar to the virus that was circulating in Equatorial Guinea. However, with that being said, there was no further reports of polio or onset of paralysis reported in Brazil to date and no further samples from the sewage detected a positive for an strains of poliovirus.

Despite not having spread the disease to Brazil, according to the International Health Regulations (IHR), temporary recommendations issued by the Director General of WHO on 5 May 2014 considered Equatorial Guinea to be a polio exported country and hence the country therefore focused on ensuring all residents and long-term visitors of more than 4 weeks that travel internationally, receive a supplementary dose of poio vaccine between 4 weeks to 12 months before departure. [10]

Reference:
[10] Update on polio in Equatorial Guinea. (2014, July ). Retrieved July 30, 2015, from http://www.who.int/csr/don/2014_07_17_polio/en/


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