Polio-Ashley

toc Polio Virus

Ashley Weekes

=**History/Background Information**= Jakob (or Jacob) von Heine, a German physician released the first medical reports describing the condition, Poliomyelitis in 1840. Karl Landsteiner identified the causative agent for poliomyelitis, the poliovirus in 1908. The first major outbreak of Polio in the U.S was in 1843 in Vermont. The most recent Polio outbreak was in Nigeria. The virus is generally located with in the Middle Eastern portion of the world. Places like Afghanistan, India, Nigeria and Pakistan remain polio-endemic. The mortality rates vary according to age for polio. 2–5% of children and up to 15–30% of adults die from poliomyelitis.

=Symptoms= There are many different types of the poliovirus. In some cases of polio the symptoms remain asymptomatic.

The two basic types of polio infections are the **minor illness** and the **major illness**. The minor illness, which is sometimes referred to as abortive poliomyelitis does not affect the central nervous system however, the major illness does and the out come can be **paralytic** or **non-paralytic**.


 * Minor illness**

People with healthy immune systems normally don’t show symptoms of polio. In very rare cases the poliovirus produces symptoms, but most of them are minor symptoms similar to the flu, for instance:

• Upper respiratory tract infection (sore throat and fever) • Gastrointestinal disturbances (nausea, vomiting, abdominal pain, constipation or, rarely, diarrhea), and influenza-like illness.


 * Major illness**

About 3% of the infections enter the central nervous system. When this happen most patients develop **non-paralytic** aseptic meningitis with systems of headache, neck, back, abdominal and extremity pain, fever, vomiting, lethargy and irritability.

Only 1 in 200 to 1 in 1000 cases actually end up being paralytic, in which case the muscles become weak, floppy, and poorly controlled, then finally completely paralyzed. The paralytic disease is also know as acute flaccid paralysis. Depending on where the paralysis is, paralytic poliomyelitis is categorized into three types of polio (Spinal being the most common):

• **Spinal Polio** – The polio virus invades the ventral gray matter section in the spinal column, which cause inflammation of the nerve cells, leading to damage of the motor neuron ganglia. • **Bulbar Polio** – The poliovirus attacks and destroys the nerves in the bulbar portion of the brain stem. • **Bulbospinal Polio** – A combination of bulbar and spinal polio.

How is the virus transmitted?
The poliovirus is easily spread through human-to-human contact. “Polio is also transmitted when bodily wastes from a person who has the disease contaminates food or water, which then is ingested by another person.” The virus can infect animals that can develop symptoms of the disease and pass it on to other living species.

=Structure/Composition= The poliovirus is made up of a RNA genome and a protein capsid. The RNA is a single-stranded, positive genome. The coat consists of RNA and non-enveloped icosahedral protein.

The poliovirus uses an immunoglobulin-like receptor to bind it and the host cell. The entry of RNA can happen in one of two ways. The RNA can “inject” itself into the host cell’s cytoplasm, which is caused by the formation of the pore in the plasma membrane or the virus is taken up by the receptor-mediated endocytosis.

Details about infection
The poliovirus infects the nerve cells. It attaches its receptors to the cell and the infection begins. When the virus is inside the cell it hijacks the cell’s assembly process to make thousands of copies of itself. The virus kills the nerve cell and then spreads to infect other cells.

=Medical Treatments= There aren’t actual treatments or cures for the poliovirus, but there are to types of vaccinations you can receive to prevent it.

OPV - oral polio vaccine IPV - inactivated polio vaccine

OPV is made with a live but weakened virus and IPV is given by injection and protects people from the poliovirus as well, but some believe it is less sufficient than the OPV vaccination.

Resources
[] [] [] [] [|http://www.cloudnet.com/~edrbsass/poliotimeline.htm] [] []