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7 Cards in this Set
- Front
- Back
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Why is polio reffered to as a disease of modern hygiene? |
fecal-oral spread, stable in raw sewage
-increased water purification reduced early infection -children did not develop immune resistance |
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In order to induce poliomyelitis, what steps must occur following virus infection of a human host? |
infection of migrating macrophages
-promotes access to the bloodstream =viremia -secondary viremia (high levels) allows neuro invasion of CNS (antibody response eliminates viremia) |
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Explain how genetic variability might be necessary for polio virulence |
in vivo in a single infected individual is required to infect the CNS and cause disease "Genetic bottleneck" -mutants can escape intestine |
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Name some positive arguments for polio eradication |
-spending billions of $ in WHO that could be used for other diseases -no children paralyzed by polio |
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Name some negative arguments for polio eradication |
-polio can be chemically synthesized =if vaccination stops -herd immunity not maintained -circulating vaccine derived polio could reinfect -revert to neurovirulence |
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What are some differences between the Salk and Sabin vaccines? |
Salk= inactivated poliovirus vaccine (IPV)
-more expensive than OPV, requires needle -can use in immunocompromised patients -incidents of incomplete inactivation =(cutter incident) -protective antibody response highest level in blood (non-existent in intestinal tract [IgA]) Sabin= oral polio vaccine (OPV) -Inexpensive, easy to give (drop on tongue) -can't be used in immune compromised -incidents of contamination with other virus =(SV40) -High level intestinal tract antibody (IgA) -low level reversion to virulence -spread in close contacts to vaccine ="free" immunizations =originally thought not capable of efficient sustained spread ^^^critical complication in eradication effort |
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Will eradication of polio be successful? |
No because -there can always be isolated cases in hard to reach areas -non reported cases -possibility of vaccine derived polio reverting to neurovirulence. |
