The human Enteroviruses are ubiquitous viruses that are transmitted from person to person via direct contact with virus shed from the gastrointestinal or upper respiratory tract. The enteroviruses belong to the Picornaviridae family of viruses and are traditionally divided into 5 subgenera based on differences in host range and pathogenic potential. Each subgenus contains a number of unique serotypes, which are distinguished based on neutralization by specific antisera. The subgenera include polioviruses, coxsackievirus (groups A and B), and echoviruses. Enteroviruses cause a wide range of infections. Poliovirus, the prototypical enterovirus, can cause a subclinical or mild illness, aseptic meningitis, or paralytic poliomyelitis, a disease that has been eradicated in the United States and other developed countries. The nonpolio viruses (group A and B coxsackieviruses, echoviruses, enteroviruses) continue to be responsible for a wide spectrum of diseases in persons of all ages, although infection and illness occur most commonly in infants.

Meningitis is a clinical syndrome characterized by infl ammation of the meninges. Clinically, this medical condition manifests with meningeal symptoms (eg, headache, nuchal rigidity, photophobia) and an increased number of white blood cells in the cerebrospinal fl uid (CSF). Depending on the duration of symptoms, meningitis may be classifi ed as acute or chronic. Acute bacterial meningitis denotes a bacterial cause of this syndrome. Depending on the specific bacterial cause, the syndrome may be called, for example, Streptococcus pneumoniae meningitis, Neisseria meningitis, or Haemophilus influenzae meningitis.

JC Virus and BK Virus are the most important Poliomaviruses causing respectively multifocal leukoencephalopathy and nephropathy in immunocompromised patients.