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A Devastating Disease: Polio

A Devastating Disease: Polio. By Deshae Gehr. The Poliovirus. Causes disease Poliomylitis, literally meaning “gray spinal cord inflammation It is a virus There are three types of poliovirus and many strains of each type It is contagious: usually spread from person to person.

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A Devastating Disease: Polio

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  1. A Devastating Disease: Polio By Deshae Gehr

  2. The Poliovirus • Causes disease Poliomylitis, literally meaning “gray spinal cord inflammation • It is a virus • There are three types of poliovirus and many strains of each type • It is contagious: usually spread from person to person. • Only harmful to humans

  3. What is a virus? • A pathogen that is not actually living (debated) • Depends on a host cell to live • Contains genetic material (RNA) enclosed by a capsid that protects the viral genetic material until it cann find a host • Inserts genetic material into host cells, and uses cell to manufacture more viruses. • Destroys cell when new viruses burst out

  4. Lytic: When a dormant virus is stimulated and it begins to use the cell to manufacture new viruses, ultimately killing it. Lysogenic: When viruses remain dormant inside host cells for a period of time Lytic vs. Lysogenic

  5. Overview: • Poliomylitis is caused by the poliovirus which belongs to the genus Enterovirus. • They contain RNA, and target the gastrointestinal tract • Structure: it is a single RNA genome enclosed in a protein shell (capsid). • There are 3 groups of polioviris: • Poliovirus type 1, 2, and 3 • Each has a slightly different capsid protein • PV1 is the most common, and most closely associated with paralysis

  6. Polio • 4 different kinds: Spinal, bulbar,bulbospinal, paralytic • All can result in paralysis of different parts of the body • Poliovirus spreads along certain nerve fiber pathways destroying motor neurons within the spinal cord, brain stem, or motor cortex. • This leads to the development of paralytic poliomyelitis in certain parts of the body, depending on where the central nervous system is damaged, • Inflammation associated with nerve cell destruction often alters the color and appearance of the gray matter in the spinal column causing it to appear reddish and swollen • The likelihood of developing paralytic polio increases with age • Severity of paralysis also increases • Paralysis in children occurs in only 1 in 1000 cases. • In adults, paralysis occurs in 1 in 75 cases (http://en.wikipedia.org/wiki/Poliomyelitis#Cause)

  7. Early Symptoms: • high fever • Headache • Stiffness (back and neck) • weakness of various muscles • sensitivity to touch • difficulty swallowing • muscle pain • loss of reflexes • Irritability • Constipation • difficulty urinating • Paralysis develops 1-10 days after early symptoms begin • Usually continues for 2-3 days, and complete soon after

  8. How polio enters the body: • The virus enters through the mouth • It multiplies in the throat and gastrointestinal tract • It gets into the bloodstream and is carried to the central nervous system • It replicates there • It attacks motor neuron cells, ultimately killing them. • (Motor neurons control muscles for swallowing, circulation, respiration, and the trunk, arms, and legs) • http://americanhistory.si.edu/polio/virusvaccine/how.htm

  9. Attaching to the cells: • Human nerve cells have a protruding protein structure on their surface • The polio virus comes in contact with the nerve cells, the protruding proteins act as receptors and attach to the cell • The virus injects its genetic material (RNA) into the cell, causing the cell to become an assembly line for manufacturing new viruses. (see slide on how viruses work) • The polio virus usually enters the lytic cycle

  10. http://americanhistory.si.edu/polio/virusvaccine/how.htm • 1. Polio virus approaches nerve cells vai bloodstream • 2. nerve cell receptors attach to virus. • 3. viral capsid breaks to release RNA. • 4/5.RNA takes over ribosomes: cell’s protein assembly, to make more viruses. • 6/7. Newly manufactured viruses burst out of cell (killing it) and they move on to new nerve cells

  11. Polio: Transmission • Polio is highly contagious • Spread from human contact • Transmitted in fecal-oral manner (generally occurs when food or water is contaminated), or oral to oral manner • Its incubation period is anywhere from 3 to 35 days • Most contagious 7-10 days before, and 7-10 days after

  12. Polio: Transmission • It was very prevalent among children, although anyone can get it, especially those with compromised immune systems • Climate has been known to affect the transmission • Temperate climates: with this climate the transmission peak for polio is in the summer and fall. • However, with tropical climates the seasonal gap is not as noticable

  13. Treatment: • There is no cure for polio • Treatment is lessening severity of the symptoms (of weakness, paralysis) • Some examples: • antibiotics to prevent infections in weakened muscles • Pain-relieving drugs • moderate exercise and a nutritious diet • Long-term rehabilitation; physical therapy • Braces (body) • Corrective shoes • Orthopedic surgery • Iron lungs (portable ventilators)

  14. The Vaccine: • Now there is a vaccine developed in 1952 by Jonas Salk • Albert Sabin later developed an oral polio vaccine • Vaccines work by exposing the person to the virus in a controlled fashion so the body creates antibodies, that result in immunity.

  15. Polio is a disease that has existed since Egyptian times or before The 1st known clinical description is reported in 1780 by English physician, Michael Underwood 1st seen as a distinct condition in 1840 by Jakob Heine. Jakob Heine http://upload.wikimedia.org/wikipedia/en/2/2e/Jakobheine.jpg Polio: History

  16. Polio: History • Polio was a devastating disease in the 20th century, particularly in the United States and Europe. • Populations exposed to poor sanitation had become immune to the virus over time • However, developing countries were increasingly getting better sanitation • The natural immunity built up due to constant exposure made the general population more at risk (esp. 6 month-olds to 4 year-olds)

  17. Polio: History • Polio infections rapidly increased in new age countries beginning in 1900. • The rate of death and paralysis from polio also increased drastically • 1952: United States, had the worst epidemic in the nation's history. • 58,000 reported cases: 3,145 died; 21,269 were left with mild to disabling paralysis

  18. http://www.ucmp.berkeley.edu/alllife/virus.html • http://en.wikipedia.org/wiki/Poliomyelitis • http://kidshealth.org/parent/infections/bacterial_viral/polio.html • http://upload.wikimedia.org/wikipedia/en/2/2e/Jakobheine.jpg • http://americanhistory.si.edu/polio/virusvaccine/how.htm

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