The Picornaviridae family comprises
of a large number of very small RNA (pico:small, rna;RNA) viruses with a size
of 27-30 nm. They are nonenveloped viruses, resistant to ether and other lipid
solvents. Two groups of picornaviruses are of medical importance, the enteroviruses that parasitise the
enteric tract and the rhinoviruses that infect the nasal mucosa. Enteroviruses
include Polioviruses type 1, 2, 3, Coxsackie viruses A & B, Enterovirus
type 68-72.
Polioviruses causes poliomyelitis, a very ancient disease.
