Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm icosahedral capsid. The viruses in this family can cause a range of diseases including the common cold, poliomyelitis, meningitis, hepatitis, and paralysis.
Picornaviruses constitute the family Picornaviridae, order Picornavirales, and realm Riboviria. There are 158 species in this family, assigned to 68 genera. Notable examples are genera Enterovirus (including Rhinovirus and Poliovirus), Aphthovirus, Cardiovirus, and Hepatovirus.