Bulbar polio

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The result of an infection of one of the three strains of the poliovirus (PV). Bulbar Polio attacks the central nervous system (CNS) and in severe cases, the infected person must be placed in an iron lung or put on a ventilator. The fatality rate for bulbar polio is lowest for children and highest for adults-with mortality rates ranging from twenty five to seventy five percent.

Polio (infantile paralysis) is a communicable disease with is categorized as a disease of civilization. Polio spreads through human-to-human contact, usually entering the body through the mouth due to faecally contaminated water or food. The poliovirus is a small RNA [ribonucleic acid] virus that has three different strains, and is extremely infectious. The virus invades the nervous system, and the onset of paralysis can occur in a matter of hours. Polio can strike a person at any age, but statistically over fifty percent of the cases occurred to children between the ages of three to five. The incubation period of polio, from the time of first exposure to first symptoms is from three to thirty five days.

1 Symptoms of Polio Infection
2 Spinal Paralytic Polio
3 Bulbar Polio
4 History and Outbreaks
5 Polio Epidemics
6 A Vaccine is Developed
7 References

[edit] Symptoms of Polio Infection

The Poliovirus can spread widely before physicians detect the first signs of a polio outbreak and infections-which are the onset of paralysis. Surprisingly, most people infected with the poliovirus have no symptoms or outward signs of the illness, and are never aware they had been infected. After the person is exposed to the poliovirus, the virus is expelled through faeces for several weeks. It is during this time that a polio outbreak can occur in a community. Being vaccinated does not protect a person from becoming infected; the inoculation prevents the virus from damaging the nervous system. Vaccinated individuals who become infected by the poliovirus will not develop polio, but can carry the virus in their intestines and can pass it to others. The three strains of poliovirus result in non-paralytic polio, paralytic polio, and bulbar polio. In all forms of polio, the early symptoms of infection are fatigue, fever, vomiting, headache, pain in the neck and extremities. Non-paralytic polio will result in fever, vomiting, abdominal pain, lethargy, and irritability. Some muscle spasms in the neck and back, with muscles generally tender to the touch.

[edit] Spinal Paralytic Polio

One strain of the poliovirus attacks the spinal column where it destroys the anterior horn cells which control movement of the trunk and muscle limbs. This strain of polio is known as paralytic polio. Although this strain of the poliovirus can lead to permanent paralysis, less than one in two hundred with symptoms will result in paralysis. The most common paralysis will affect the legs. Once the poliovirus invades the intestines, it can is absorbed by the capillaries in the walls of the intestine and then is carried by the bloodstream throughout the body. The poliovirus attacks the spinal column and the motor neurons, which control physical movement. It is during this period of infection that mild flu-like symptoms occur. However, people who have no immunity or have not been vaccinated, the virus usually goes on to infect the entire spinal column and the brain stem. This infection affects the central nervous system (CNS)-spreading along nerve fibers. As the virus continues to multiply in the CNS, the virus destroys motor neurons, which control muscle movement. Motor neurons do not regenerate and any affected muscles no longer respond to CNS commands. The most common paralysis occurs to the muscles of the legs. A leg (or legs in total paralysis of the legs) the limb becomes floppy and lifeless - a condition known as acute flaccid paralysis (AFP). An extreme infection of the CNS can cause extensive paralysis of the trunk and muscles of the thorax and abdomen (quadriplegia).

[edit] Bulbar Polio

Bulbar Polio is thought to be the result of a person having no natural resistance to the poliovirus, so the brain stem is affected. This strain of the virus attacks the brain stem, which contains the motor neurons that control breathing. Damage to these neurons often results in paralysis of the respiratory muscles. Bulbar polio involved the brain stem where the centers for the cranial nerves are located. The cranial nerves involve smell (olfactory), vision (optic), three cranial nerves control the various muscles that control eyeball movements, the trigeminal nerve and facial nerve which innervate cheeks, tears, gums, and muscles of the face, etc, the auditory nerve which provides hearing, the glossopharyngeal nerve which controls in part swallowing, and functions in the throat, the hypoglossal nerve which controls tongue movement and the vagus nerve which sends signals to the heart, intestines, respiratory (lungs) and the accessory nerve that controls upper neck movement. Thus bulbar polio could affect any or all of these functions. Death from bulbar usually occurred from damage to the cranial nerve sending the signal to breathe to the lungs. Bulbar victims could also die from damage to the swallowing function because a victim could drown in their own secretions unless adequately suctioned or given a tracheostomy to suction secretions before the secretions entered the lungs. It was difficult to have a tracheostomy and still be able to tolerate the airtight collar of an iron lung. Death also occurred from the overwhelming invasion of the virus into other parts of the brain causing coma and death. Bulbar polio can be fatal, and the infected person must be placed in an iron lung. The mortality rate of bulbar polio ranges from twenty-five to seventy-five percent, with the variable being the age of the person. To this day there are still polio survivors who must spend their entire day or most of their day in an iron lung or attached to an assistive respiratory machine to stay alive. As mentioned, without respiratory support, bulbar polio usually results in death. Of those who become infected, from five to ten percent die when their breathing muscles become immobilized. Bulbar polio and spinal polio often coexist. They are both a subclass of paralytic polio. Paralytic polio is not necessarily permanent. One can have had paralytic polio and recover seemingly normal function.

[edit] History and Outbreaks

Polio is a highly contagious infection caused by a virus that has three distinct strains, called types I, II and III. It is noteworthy to recognize that exposure and a resulting immunity to one type doesn't confer immunity to the other two. Type I causes the most paralysis and is the frequent cause of most of the polio epidemics of the first half of the 20th century. The poliovirus enters the body through the mouth, either by contaminated hands or contaminated food or water after coming into contact with expelled feces, which contains the poliovirus. Polio epidemics occurred usually in the summer and early fall because the poliovirus flourishes in warm weather. Children were more often affected than adults were which is why the disease carried the moniker infantile paralysis.

Franklin D. Roosevelt may have contracted polio in 1921. Yet his age (39 years) and many features of his illness are more consistent with a diagnosis of Guillain-Barré syndrome (an autoimmune peripheral neuropathy). A peer-reviewed study published in 2003, ^[1] using Bayesian analysis, found that six of eight posterior probabilities favored a diagnosis of Guillain-Barré syndrome over poliomyelitis. Regardless of the cause, the result was that Roosevelt was totally and permanently paralyzed from the waist down. He could sit up and, with aid of leg braces, stand upright, but could not walk. Evangelist Jack Coe contracted bulbar polio in 1956 and died due to complications.

Before the 20th century, there were cases of polio, but they were few and no major outbreaks occurred. The question then is how did polio emerge from centuries of obscurity to becoming a killer in just a few decades? The answer lies in a major change in sanitation practices. Before the advent of modern indoor plumbing and sewage systems, many cities had open sewers that were no more than gutters and outhouses in the backyard. Almost everyone had, at one time or another, been exposed to polio, and with open sewers and outhouses the norm--there was ample opportunity to contract polio. Polioviruses infected generations of babies, who were protected in part by antibodies passed on to them by their mothers. When a child became infected with the poliovirus the results were flu-like or cold-like symptoms. The diagnosis of polio was rare because the symptoms were often indistinguishable from other childhood diseases.

[edit] Polio Epidemics

Cases of paralytic polio began to rise due to the change in public sanitation and other health measures, such as purification of the water supply and milk pasteurization. Better hygiene meant that babies and young were not receiving some immunization from their mothers. When the disease struck older children or adults, it was more likely to take the paralytic form. In northern Europe and the United States, epidemics of paralytic polio began to appear in the late 19th and early 20th centuries, though small. Polio's full impact wasn't felt in the United States until the summer of 1916, when an outbreak resulted in 27,000 people paralyzed, and 6,000 deaths. The 1916 epidemic caused widespread panic and thousands fled the city to nearby mountain resorts. Movie theaters were closed, meetings were cancelled, and public gatherings were almost nonexistent. Children were warned not to drink from water fountains; and children were told to avoid amusement parks, pools, and beaches. From 1916 onward, a polio epidemic appeared each summer in at least one part of the country, with the most serious occurring in the 1940s and 1950s. In the United States, it would be the 1952 polio epidemic that marked the worst outbreak in the nation's history. Of the nearly 58,000 cases reported that year; 3,145 died and 21,269 were left with mild to disabling paralysis. Statistically, more children died of polio in 1952 than of any other infectious disease.

[edit] A Vaccine is Developed

The eradication of polio in the developed world was a slow process. Since polio could not be treated after one was infected, the key was in developing a vaccine. In 1954, the National Foundation for Infantile Paralysis sponsored a field trial a vaccine developed by Jonas Salk, M.D. In this massive trial approximately 1.8 million children participated, and the result was the Salk vaccine was highly effective in preventing polio. The Salk vaccine was licensed for use in 1955, an intense public health campaign was mounted to inoculate all American children. In 1961, Albert Sabin, M.D ‘s attenuated live virus vaccine was licensed. This vaccine was administered orally, with children given a sugar cube soaked in the liquid vaccine. Polio has been virtually eliminated in the United States. Both vaccines contain all three virus strains and effectively prevent polio. The most recent polio epidemic in the United States occurred in 1979, when 10 Amish children came down with the disease (Amish generally refuse vaccinations on religious grounds).