Disease
Poliomyelitis (Polio)

Author
Deborah Malin, Biol 230, Spring 2009

Causative Agents
            The virus poliomyelitis is caused by the group of viruses called enteroviruses.  They are made up of single stranded RNA viruses.  Enteroviruses are part of the small RNA viruses called Picornaviridae.  Viruses get their ability to cause an immune response due to the capsid (def) that is around the RNA.

Epidemiology
            Polio was a very common virus that affected children in the United States and other countries before the polio vaccine (def) was established in 1955.  In today’s day and age very few people contract the polio virus.  Although polio can be contracted by adults it is more commonly contracted by young children.  Polio is often found more in countries where there is low socioeconomic standards (def), because these areas often do not have proper hygiene and sanitation.   Polio virus often occurs during the summer and fall because that is when enteroviruses most commonly occur.

            Most people that are infected with the polio virus show no symptoms; therefore they don’t even know that they ever had it.  A lot of people that are infected with the polio virus come away unharmed.   However, if not dealt with in the proper manner it can lead to paralysis (def) of the legs and possibly other areas.  If ones breathing muscles become paralyzed it can lead to death.  Only a very small percentage of people that are infected with the polio virus become paralyzed. 
           

Transmission
            Poliomyelitis can be transmitted by two ways.  It can be transmitted through the fecal-oral route (def), or by the oral-oral route (def).  The way the polio virus leaves the body is by slowly excreting it through the feces.  During this stage if proper hygiene and sanitation measures are not taken, many people can contract the virus.  It is commonly spread through water and food that was contaminated by human waste.  Polio virus enters the body by way of the mouth.  Once in the intestines it multiplies, it can then enter the bloodstream and enter the organs.  If the infection continues to spread, it can enter the central nervous system.

Signs and Symptoms
            Often one does not show any signs and symptoms of polio, therefore they may never know that they were even infected by the virus.  As the virus progresses the symptoms get worse and worse.  There are four stages of poliomyelitis.  In stage one a person experiences a slight fever, headache, cough, and joint pain which are common flu-like symptoms.  During stage two a person experiences no symptoms for a couple of days.  The third stage has the same characteristics of stage one but with a few additional symptoms.  They include, nausea, vomiting, diarrhea, stiff neck, and muscle pain.  Paralysis occurs in stage four.  Paralysis from polio is not necessarily permanent and can be reversed.

Prevention and Treatment
            Poliomyelitis has no cure and therefore it is important to prevent it from occurring.  The only way to prevent someone from becoming infected by the polio virus is by vaccinating them with the polio vaccines.  There are currently two types of vaccines available, the OPV (def) vaccine and the IPV (def) vaccine.

            OPV vaccine was the first vaccine developed against polio.  This vaccine caused contact immunization, which means that someone who comes in contact with a child that was vaccinated possibly became immune also without having to get vaccinated.  There was a slight problem with this vaccination.  On rare occasions it caused the child who was vaccinated or the person who came in contact with the vaccinated child to contract paralytic polio.

            The IPV vaccine was created to cause the body to produce antibodies, to stimulate the body’s immune system to prevent the virus from infecting the person.  The Center for Disease Control discontinued the OPV vaccine because of the possibility it carries to cause paralytic polio.  Now in the United States the only vaccine given for the prevention of polio is the IPV vaccine. 

              Once a person becomes infected with the polio virus there is no treatment that can be given to cure the virus.  Polio is caused by a virus, therefore antibiotics which are used for bacteria are not effective.  The only thing that can be done for a person with polio is to give them care that will decrease their symptoms.  For example give them pain medication and help them with breathing if they are having trouble due to paralysis. 

Bibliography
1. Retrieved on April 19, 2009 from: http://www.medterms.com/script/main/art.asp?articlekey=4765
2. Retrieved on April 19, 2009 from: http://www.nlm.nih.gov/medlineplus/polioandpoliosyndrome.html
3. Retrieved on April 19, 2009 from: http://www.cdc.gov/vacines/vpd-vac/polio/default.htm
4. Retrieved on April 19, 2009 from: http://www.polioeradicatin.org/disease.asp
5. Retrieved on April 19, 2009 from: http://polio.emedtv.com/polio/treatment-for-polio.html
6. Retrieved on April 19, 2009 from: http://kidshealth.org/parent/infections/bacterial_viral/polio.html#
7. Retrieved on April 19, 2009 from: http://emedicine.medscape.com/article/963637-overview
8. Retrieved on April 19, 2009 from: http://www.myhandicap.com/int-polio.html