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/

Cameroon Case (Part IV)

6 September 2014 - In Cameroon, 2 new wild poliovirus type 1 (WPV1) cases were reported from the East Region with the onset of paralysis on 26 June and 9 July 2014. Genetic sequencing suggested that this wild poliovirus was a continued wild poliovirus circulation. Gaps in surveillance result in undetected transmission and geographic expansion to new areas of the country.

The outbreak in Cameroon has been ongoing since at least October 2013. The outbreak had also spread internationally to Equatorial Guinea in March 2014. Due to the possible high influx and expanding circulation of vulnerable refugee populations from Central African Republic, Who had elevated the risk assessment of Cameroon to VERY HIGH. Further undetected circulation cannot be ruled out as the risk of virus spreading to Central African Republic is considered to be particularly high given the large scale population movements from there to Cameroon.

In May 2014, Director-General of WHO declared Cameroon as one of the states of international spread of wild poliovirus to be a Public Health Emergency of International Concern (PHEIC), under the criteria for 'states currently exporting wild poliovirus ' and was therefore recommended to implement strict measures to lower the risk of further international spread.

Cameroon conducted 7 nationwide supplementary immunization activities (SIAs) in 2014 followed by subnational SIAs for 23-26 August and 4-7 September in the 2 regions, East and Adamaoua, of the country, with the intention of mainly immunizing children less than the age of 10. Central African Republic also responded to the possible outbreak in the country by international spread from Cameroon by starting a series of 5 sub-national polio immunization activities that will cover the western half of the country which will end with the September 2synchronized round covering the central block of Africa.

Outbreak response quality in Cameroon has varied by geographic area and the confirmation of new cases and the possibility of undetected cases resulted with the additional emergency outbreak responses to further increase its measures taken against the possible spread of the poliovirus. Once again, WHO had stressed the importance of maintaining a fully immunized community in th ecountry and surrounding neighboring countries as well as improving the surveillance of possible cases of polio in the country to be reported to World Health Organization for further monitoring of the spread of the disease. [11]

Reference:
[11] Poliovirus in Cameroon – update. (2014, September ). Retrieved June 29, 2015, from http://www.who.int/csr/don/2014_09_06_polio/en/
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