What is the pathophysiology of herpes simplex virus (HSV) keratitis?

Updated: Jan 18, 2019
  • Author: Jim C Wang (王崇安), MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Answer

HSV is a DNA virus that commonly affects humans. Infection occurs by direct contact of skin or mucous membrane with virus-laden lesions or secretions. HSV type 1 (HSV-1) is primarily responsible for orofacial and ocular infections, whereas HSV type 2 (HSV-2) generally is transmitted sexually and causes genital disease. HSV-2 may rarely infect the eye by means of orofacial contact with genital lesions and occasionally is transmitted to neonates as they pass through the birth canal of a mother with genital HSV-2 infection.

Primary HSV-1 infection occurs most commonly in the mucocutaneous distribution of the trigeminal nerve. It is often asymptomatic but may manifest as a nonspecific upper respiratory tract infection. After the primary infection, the virus spreads from the infected epithelial cells to nearby sensory nerve endings and is transported along the nerve axon to the cell body located in the trigeminal ganglion. There, the virus genome enters the nucleus of a neuron, where it persists indefinitely in a latent state.

Primary infection of any of the 3 (ie, ophthalmic, maxillary, mandibular) branches of cranial nerve V can lead to latent infection of nerve cells in the trigeminal ganglion. Interneuronal spread of HSV within the ganglion allows patients to develop subsequent ocular disease without ever having had primary ocular HSV infection. [5]


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