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 may contain external structures and a membrane. Viruses are obligate intracellular parasites--meaning that they require host cells to reproduce. In the viral life cycle, a virus infects a cell, allowing the viral genetic information to direct the synthesis of new virus particles by the cell.There are many kinds of viruses.iruses are obligate intracellular parasites--meaning that they require host cells to reproduce. In the viral life cycle, a virus infects a cell, allowing the viral genetic information to direct the synthesis of new virus particles by the cell.