What is the pathophysiology of enteroviruses?

Updated: Mar 01, 2018
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Enteroviruses are transmitted predominantly via the fecal-oral route. However, there are some exceptions, including coxsackievirus A21, which is spread mainly by respiratory secretions, [14] and enterovirus 70, which is shed in tears and spread via fingers and fomites. [15]

Upon entry into the oropharynx, the virus replicates in submucosal tissues of the distal pharynx and alimentary tract. [16] Viral particles are shed in the feces and in upper respiratory tract secretions for days prior to symptom onset. The average incubation period is 3-10 days, during which the virus migrates to regional lymphoid tissue and replicates. Minor viremia results, which is associated with the onset of symptoms and viral spread to the reticuloendothelial system (spleen, liver, bone marrow). [17]

Dissemination to target organs follows, and viral replication in target organs produces the major viremia with possible secondary seeding of the CNS. Potential target organs include the skin and CNS. Infectious virus is shed from the upper respiratory tract for 1-3 weeks and from the feces for 3-8 weeks. Enteroviruses undergoes a high rate of mutation during replication in the gastrointestinal tract, where single-site mutations can occur in the 5' noncoding region of the attenuated polioviruses; this can lead to prolonged excretion and neurovirulence. [18]

The neuropathy of paralytic diseases caused by enteroviruses is due to direct cellular destruction. Neuronal lesions occur mainly in anterior horn cells of the spinal cord. The 3 serotypes of poliovirus all bind to the cell surface receptor CD155.


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