polio

• Poliomyelitis is an infectious disease caused by an enterovirus C belonging to the Picornaviridae family
• Polio is a single stranded RNA virus
• Polio has caused paralysis and death for much of human history
• For centuries it was endemic throughout the world and rarely caused epidemics
• Epidemic outbreaks were unknown before the 20th century because the virus was endemic in communities and infants were exposed to the virus very early while receiving antibodies from their mother's milk
• Poliomyelitis is an Old World Disease
• Enterovirus


  One of three type of an Ultra-microscopic virus that causes poliomyelitis
• Transmission

  1. Virus enters through the mouth

  2. Fecal-oral transmission

  3. Oral-oral transmission

  4. Aerosol

  droplets from the upper repiratory tract during the early days of infection
• Incubation period


  Varies from 3-30 days
• Early Symptoms

  • Fever
  • Sore throat
  • Stiff neck
  • Aching muscles
• Pathogenesis

  1. Virus replicates in pharynx and GI tract

  2. Enters lymphatics

  3. Enters the blood

  4. Infects the central nervous system

  5. Antibody in serum by day 10

  6. Virus excreted in feces by day 12
• Poliomyelitis Lesions

  • Only a SMALL population of those infected with polio will become ill
  • Destruction of the anterior horn cells of the spinal cord and the brain stem
  • Lower motor neuron type of paralysis with flaccid paralysis but normal sensation
  • Muscles in the lower limb are much more affected than the upper limb
  • Very painful!
  • Treatment in the early convalescent stage is mainly directed at treating muscle and spasms to prevent these deformities.
• The "Clean Disease": "Middle Class Plague"


  • In rural communities with primitive sanitation facilities, poliovirus circulated freely
  • In such communities, babies experience sub-clinical immunizing infections while still protected by maternal antibodies- a form of NATURAL vaccination
  • In communities with sanitation, children were not getting exposed until school age and then some got disease symptoms
• During the nineteenth century, industrialization and urbanization changed the pattern of poliovirus transmission

  
  

  • Dense urban populations and increased traveling afforded opportunities for rapid transmission of the virus
  • Improved sanitation broke the natural pattern of virus transmission. Children were likely to encounter the virus for the first time at a later age and without the protection of maternal antibodies
  • these children were at greater risk when they did become infected and its believed that these social changes account for the altered pattern of disease
• Polio appeared in the hot summer months in the US during the first half of the 1900's
• Improved sanitation and household cleanliness, septic systems and well water resulted in populations of people who had no immunity to polio
• Epidemics began in the early 1900s and up to half a million people died around the world each year of polio
• Proof polio was infectious

  
  

  • in 1908, Drs Karl Landsteiner and Erwin Popper managed to induce polio in old-world monkeys by injecting them with extracts of the spinal cord of a boy who had died from polio work in Vienna. First animal model (won Nobel prize in 1930)
  • The disease could then be transmitted from monkey to monkey, providing an invaluable model of the disease polio (Simon Flexner) at Rockefeller Institute in New York
• Historical Landmarks of Poliomyelitis


  • 1908 — Transmission of poliomyelitis to a monkey by Landsteiner
  • 1909 — Passage of the virus through a monkey by Simon Flexner
  • 1916 --- First large epidemic/pandemic: 27,000 people infected/6,000 deaths in U.S.
  • 1949 — Growth of the virus in tissue culture. Dr John Enders
  • 1951 — Three types of polio virus isolated and identified
  • 1954 — First large scale trial of Salk vaccine (killed vaccine) by injection
  • 1958 — First general use of Sabin vaccine (live attenuated vaccine) by mouth
• Franklin Delano Roosevelt


  • Three term President 1933-1945
  • Developed Polio in 1921
  • Paralyzed from waist down
  • Could not walk without body brace
  • Was in a wheelchair – reporters told not to photograph
  • Great promoter of philanthropy for polio
• Warm Springs Georgia

  • The nationwide crusade against poliomyelitis (polio) began at Warm Springs, Ga., a spa where Franklin D. Roosevelt first went in 1924, seeking the therapeutic effects of the warm spring waters
  • In 1926, Roosevelt purchased the whole property and, a year later, with the help of his former law partner, Basil O'Connor, established the nonprofit Warm Springs Foundation
• During the Great Depression, the Georgia Warm Springs Foundation, in need of funds, started to appeal to the general public. Initially, money was raised through an annual "President's Birthday Ball," with FDR and a variety of celebrities like movie stars participating
• In January 1938, alarmed by decades of worsening polio epidemics and the terrible toll the virus was taking on America's youth, President Roosevelt established the National Foundation for Infantile Paralysis
• Comedian Eddie Cantor coined the phrase "March of Dimes" appealing to radio listeners all over the country to send their dimes directly to the White House. The campaign proved to be hugely successful. The National Foundation for Infantile Paralysis officially changed its name to the March of Dimes in 1979
• In 1948, with funding provided by the March of Dimes, Dr. Jonas Salk was able to grow the three known types of polio virus in his lab and eventually to develop an experimental killed-virus vaccine
• In the summer of 1952, Dr. Salk tested the vaccine on children who'd already recovered from polio. Following vaccination, the level of polio antibodies in their blood increased. The next step was to try it on volunteers who had not had polio–including himself, his wife, and their children. The volunteers all produced antibodies; none got sick with polio
• Later, in 1962, an oral polio vaccine, developed by Dr. Albert Sabin, with funding from the March of Dimes, was licensed
• Iron Lung


  Ventilator used to keep polio victims alive by assisting with respiratory failure caused by paralysis of the intercostal muscles and diaphragm
• Sister Kenny


  • Australian nursing sister who became world famous for her revolutionary treatment of infantile paralysis (polio)
  • Treatment involved the application of hot packs and the exercising of children's limbs, at first passively and then with graduated active movements
  • There was an improvement in her patients and a scientific study of her work was inconclusive
  • In 1983, after Australia called her methods cruel, she went to the US where experiments proved her treatment helped in recovery.
  • Lead to physical therapy!
• Vaccine

  
  

  • Dr. Jonas Salk believed that an inactivated virus techniques similar to the method used for the influenza vaccine would yield a safe and effective poliovirus vaccine
  • In the spring of 1952, after two years of development, Salk began experimental trials of his killed virus vaccine
  • Large scale trials were begun in 1954
• Salk's Vaccine


  • Very effective in preventing important clinical signs of disease
  • Immediately put into widespread use by 1954
• Sister Kenny's work led to physical therapy
• Inactivated Polio Vaccineby Jonas Salk

  • IPV produces strong immunity in the blood, protecting vaccinated individuals from acquiring paralytic poliomyteitis.
  • not so good at stopping virus replication in gut and shedding in feces
  • immunity was NOT life long
• Philanthropy Vaccine

  • Polio vaccine manufactured by Cutter Laboratories in Berkley, California had been improperly inactivated virus vaccine and contained like poliovirus.
  • 204 got polio; over 150 were paralyzed and 11 died.
  • Recalled by the US Government.
  • Led to establishment of the Standards Bureau known today as the Food and Drug Administrator (FDA)
• Second Polio Vaccine

  • Dr. Albert Sabin worked for many years to develop a live, attenuated (weakened) polio vaccine
  • Invited to Russia to test his vaccine
  • Example of cold war medical cooperation between US and Soviet Union
  • In 1957, trial begun and the vaccine went into widespread
  • In many ways, live vaccine gives longer immunity against polio than the inactivated vaccine and builds up immunity in the gut, so did not shed as much virus
• Live Attenuated Oral Polio Vaccine (OPV)by Albert Sabin


  Produces a long-lasting immune reaction in the lymphatic tissue of the small intestine which effectively acts as a barrier to polio passing through the gut, but has a risk of vaccine-associated poliomyelitis
• Most people should get polio vaccine when they are children. Children get 4 doses of IPV at 2 months, 4 months, 6-18 months, and a booster at 4-6 years
• Oral Polio Vaccine (OPV) has not been used in the United States since 2000 but is still used in many parts of the world
• In 1960, Benjamin Sweet and Maurice Hilleman isolated a virus called SV40 from monkey kidney cells culture used to grow the polio virus for vaccine, which had the potential to cause cancer in rodents, but there is no credible scientific evidence that this virus has had any adverse effects on humans vaccinated with the early live attenuated vaccine
• Post-Polio Syndrome


  A series of new symptoms that occur an average of 31 years after the onset of the initial polio infection and after a period of "recovery" of at least 10 years, including

  • weakness, pain, breathing and/or swallowing difficulties
  • sleep disorders
  • muscle twitching
  • gastrointestinal problems
  • muscle fatigue and/or general fatigue

  These symptoms can occur in previously-affected muscles and/or in what were previously thought to be muscles that were not affected at onset