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Poliomyelitis

Poliomyelitis. U.S. Centers for Disease Control and Prevention. Ijeoma Ohadugha 4/1/10 Infectious Diseases. U.S. Centers for Disease Control and Prevention. http://www.immune.org.nz/site_resources/Professionals/Diseases/Polio/Polio.jpg. Poliomyelitis is an infection of the CNS.

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Poliomyelitis

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  1. Poliomyelitis U.S. Centers for Disease Control and Prevention Ijeoma Ohadugha 4/1/10 Infectious Diseases U.S. Centers for Disease Control and Prevention http://www.immune.org.nz/site_resources/Professionals/Diseases/Polio/Polio.jpg

  2. Poliomyelitis is an infection of the CNS • poliós -Greek word “grey”, + myelós “spinal cord’ + suffix –itis “inflammation =poliomyelitis • Viral infection of the nerves of the CNS

  3. Poliomyelitis is caused by an enteric RNA virus • Caused by an Enterovirus called the poliovirus • Enteric, small RNA virus F.P. Williams, U.S. EPA

  4. Transmission by fecal-oral route http://www.co.washington.or.us/HHS/EnvironmentalHealth/PublicPools/

  5. Risk Factors • Not being vaccinated in areas where polio is common • infants, pregnant women, immunocompromised (eg. HIV)

  6. WHO, 2008.

  7. Three basic patterns • Subclinical infection(95% of infections),

  8. Three basic patterns • Subclinical infection(95% of infections), • Nonparalytic poliomyelitis(1-2%)

  9. Three basic patterns • Subclinical infection(95% of infections), • Nonparalytic poliomyelitis(1-2%) • Paralytic poliomyelitis(0.1–0.5%) • -result of accidental transfer of virus from GI tissue to neural tissue • Spinal polio - 79% of paralytic cases— Bulbospinal polio - 19% of paralytic cases— Bulbar polio - 2% of paralytic cases

  10. Polio afflicted everyone socially as well as medically • Franklin Delano Roosevelt • “Once you’ve spent two years trying to wiggle one toe, everything is in proportion.”—Franklin D. Roosevelt, 1945 http://americanhistory.si.edu/polio/howpolio/fdr.htm

  11. Heine named polio as a clinical condition; Lansteiner discovered the virus Jakob Heine(1840) Karl Landsteiner (1909)

  12. poliovirus enters digestive tract via mouth • Primary site of infection is epithelial and lymphoid tissue associated with the oropharynx and gut • Virus production at this site leads to a transient viremia, following which the virus may infect the CNS http://cmbi.bjmu.edu.cn/www-learn/micro-ac-uk/335/Picornaviruses.html

  13. Dual Tropism Thought to be the Cause of Poliomyelitis from Poliovirus • Reflects the distribution of the poliovirus receptor CD155 on cells lymphoid cells as well as the epithelial cells in the gut and on neurons in the CNS • Viral Tropism relies on host cell permissiveness and receptor susceptibility

  14. Virus Replicates Through Viropexis • attachment of the virus to specific cellular receptors of cells with CD155 • penetration and uncoating of the virus is energy dependent, and occurs by receptor-mediated endocytosis (viropexis)

  15. Interferons May Prevent Susceptibility of Most Cells with CD155 • CD155 is present on most human cells, so does not explain why it infects certain tissues • Recent studies-suggest human type I interferon receptors possibly prevent • Interferon- protein released by lymphocyte in response to pathogen to trigger immune defenses

  16. Only IPV used in US today • OPV known to in rare cases become virulent and cause iatrogenic (vaccine-induced) polio • Both used today in the world • IN US, only IPV used since 1990s from policy changes • Only cases of polio (8-10 per year) were from people with vaccine-induced polio

  17. Jonas Salk- Injected Poliovirus Vaccine(IPV) Albert Sabin – oral live attenuated virus (OPV) 1952 1957

  18. SV40 Contamination Concerns • In 1960, SV40 (Simian Vius-40) found in vaccine from rhesus monkey kidney cells used to prepare vaccine

  19. Vaccines with SV40 contamination was accused as cause for HIV • Accusations in 1990s that vaccines with SV40 caused conditions favorable for SIV jump from monkey to humans, causing HIV/AIDS

  20. Accusation now debunked, but stigma lingers for new reasons • New reasons for vaccination stigma such as rumors of sterility in some areas

  21. Treatment in the past often ineffective until Elizabeth Kenny’s procedures • crutches or wheelchair for motor muscle degeneration • “convalescent serum”-1920s • iron lung for respiratory failure • early 1940s- Sister Elizabeth Kenny’s procedures- hotpacks and heating pads w/massages, still used today

  22. Present Treatments Offer Relief to Symptoms • No current cure • Respiratory apparatus • Antibiotics for UTIs, medication for urine retention • Heating pads and towels for muscle spasms & pain • Physical therapy, braces, or orthopedic surgery for recovery of muscle strength/function

  23. What still needs to be done • Eradication efforts • Get rid of stigma surrounding vaccine in Africa and other polio-afflicted places • Develop new targets for polio cure

  24. References • http://www.polioeradication.org/ • https://health.google.com/health/ref/Poliomyelitis • http://www.mayoclinic.com/health/polio/DS00572/DSECTION=risk-factors • http://www.cloudnet.com/~edrbsass/poliotimeline.htm • http://www.vaccineinformation.org/polio/qandavax.as

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