Poliomyelitis is an acute viral infection caused by the Poliovirus, an enterovirus belonging to the Picornaviridae family. This virus primarily targets the anterior horn cells of the spinal cord, leading to asymmetric flaccid paralysis. The disease spreads via the fecal-oral route, with initial replication in the oropharynx and intestine. The hallmark clinical manifestation is paralytic poliomyelitis, which can result in permanent muscle weakness or paralysis. Vaccination against poliovirus has been crucial in reducing the incidence worldwide. Other viruses listed do not cause poliomyelitis.

Reference: Harrison's Principles of Internal Medicine, Kasper et al., 20th Edition.