Authored by BlueAngel on
Monday, January 12, 2004
Courtesy of Post Polio Newsletter, The Post Polio Network of WA, Inc., June 2002, Volume 13 No. 2 . I will be editing the more informative parts for our purpose of giving the gist of the article.
There are three main strains of poliovirus. They are known as PV1(poliovirus1), PV2, and PV3.
PV1, the most the most common in epidemics, produces the most severe paralysis and is known to be the culprit in WA’s 1948 and 1956 epidemics. It is classified the most severe because more deaths were likely to result. The 1954 epidemic was the PV2 strain and although there were only 5 deaths. However, like many other viruses, there are a number of smaller differences producing substrains if each of them. In fact by the time an epidemic finished, the PV had changed as a substrain from how it had been at the start of the epidemic.
PV2 is more likely to cause meningitis . People with PV2 were often diagnosed as having meningitis and may have gone into a coma, but often the paralysis was less severe.
PV3 was more likely to be found where there were sporadic cases occurring not in epidemics.
There are 12 other viruses that are closely related to polio and can cause paralysis. If they had been discovered before polio vaccines stopped polio they probably would have been recorded as other polio types. At present there is no vaccine for these other types as everything is geared at eliminating the 3 known polio strains. But people are still being paralyzed by these other strains, now called acute flaccid paralysis.
Polio belongs to the Picornavirus family. Rhinoviruses are the common cold,the common cold. Apthovirus is hoof and mouth disease. Hepatovirus causes Hepatitis C. Any of the enteroviruses as well as causing a sore tummy can cause paralysis.
Only humans can catch polio. PV attaches at special receptor sites on the cells that line the gut and the central nervous system which are encoded by a gene on chromosome 19. Antigens HLA3 and HLA7 are believed to increase the risk of paralysis occurring.
Enteroviruses, including PV, enter by the mouth, often from hand contamination from faeces, towels, etc. PV multiplies in the throat first then in the gut. It is resistant to stomach acid and passes through the gut lining to multiply, enters the blood stream and passes thence to various internal organs. Symptoms are as for any flu—fever malaise, headache, nausea, sore throat, tummy upset, muscle aches and in most cases the immune system overcomes it at this stage. From the blood it may pass to the nerves of the brain stem and spinal cord, causing muscle weakness, paralysis, heart and breathing failure.
The incubation period is 3-5 days for minor illnesses and 1-2 weeks for paralysis symptoms. Onset from ingestion of virus can be 3-35 days. So a large number of people may have had a minor dose of Polio without really being aware of it unless it got to the paralysis stage. The more severe the original flu-like illness, the more chance there was of deterioration occurring later in life (fatigue & weakness).
Major polio illness includes aseptic meningitis, polio encephalitis, bulbar polio, and paralysis alone or in any combination of these. Rarely this can lead to cerebral palsy-like and transverse-like symptoms. Less commonly recognized by medicos but familiar to many polio [patients were urinary retention, decreased limb temperature, altered sensation, sweating, sleep, cardiac and blood pressure abnormalities. With cranial nerve involvement there could have been facial, voice and swallowing weakness, blindness and deafness.
Those who had PV2 were more likely to have had encephalitic polio and possible coma (may remember bad headache). Damage to the brain can give poor memory problems, keeping awake, or falling and staying asleep.
Those who had PV3 (i.e. more likely if had polio in non-epidemic years) seem to be more prone to develop Chronic Fatigue or Parkinson's in later life.
Any areas damaged at original polio are likely to cause problems again as we age more.
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