Polio, or poliomyelitis, is a highly contagious viral infection that can lead to paralysis, breathing problems, or even death. The term poliomyelitis is from the Greek polios poliÃ³s meaning, grey myelos myelÃ³s referencing the, spinal-cord and itis. Meaning inflammation polio can be classified as either symptomatic. or asymptomatic
1 Prions are proteins that can force conformational changes in natural proteins and seem to cause disease (kuru, new variant Creutzfeldt-Jakob disease, and fatal familial insomnia).  A virus is an obligate intracellular pathogen (meaning that it must live within the cells of its host in order to reproduce).
They are obligate intracellular parasites. Before a virus has entered a host cell, it is called a virion, a package of viral genetic material. Virions can be passed from host to host through direct contact or through a vector (an animal carrier who is not affected by the virus--often insects).Inside the organism, the virus can enter the cell in various ways.hey are obligate intracellular parasites. Before a virus has entered a host cell, it is called a virion, a package of viral genetic material. Virions can be passed from host to host through direct contact or through a vector (an animal carrier who is not affected by the virus--often insects).