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).
Obligate intracellular parasites of humans include: 1  viruses. 2  Certain bacteria, including: 3  Chlamydia, and closely related species. 4  Rickettsia. 5  Coxiella. 6  Certain species of Mycobacterium such as Mycobacterium leprae. 7  Certain protozoa, including: 8  Apicomplexans (Plasmodium spp., Toxoplasma gondii and Cryptosporidium parvum).