Systemic and Ophthalmic Manifestations of West Nile Virus Infection

Yos Priestley; Marcia Thiel; Steven B. Koevary

Expert Rev Ophthalmol. 2008;3(3):279-292.

Optic Neuritis

Another rare, but notable, symptom of WNV is optic neuritis. Most patients that develop optic neuritis have WNM and present with ocular pain, blurred vision, and visual clouding or 'black fog' in both eyes. In many of the reported cases of optic neuritis, patients described onset of ocular symptoms concomitantly with other systemic symptoms and had associated chorioretinitis. Fundus examination of patients with optic neuritis revealed bilateral pale, swollen optic nerves and in many cases a few vitreous cells.^[29,64,74] An associated relative afferent papillary defect was noted, in addition to remarkable loss of peripheral vision in many cases where the bilateral optic neuropathy had an asymmetric presentation between the two eyes. Follow-up examinations revealed optic atrophy, visual acuity loss and visual field loss.^[64,74]

Optic nerve involvement is seen in many conditions, highlighting the importance of considering epidemiologic events as part of the differential diagnosis, especially in cases where patients present with acute neurologic symptoms. It is worth noting that in some cases of reported optic neuritis, patients had previously received lumbar punctures but opening pressures were not reported. Thus, increased intracranial pressure, or papilledema, may have played a role in their optic nerve swelling.^[29] Optic neuropathies are thought to develop secondarily to primary occlusion of the posterior ciliary or retinal vessels.^[60]

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Cite this: Systemic and Ophthalmic Manifestations of West Nile Virus Infection - Medscape - Jun 01, 2008.

Table 1. Estimated Percentage of Overall Infections, Median Ages Affected, Acute Clinical Features and Estimated Case Fatality Rate of the Acute Clinical Syndromes Associated with Human West Nile Virus Infection*
Variable	West Nile fever	West Nile neuroinvasive disease
Variable	West Nile fever	West Nile meningitis	West Nile encephalitis	West Nile poliomyelitis
Estimated percentage of overall infections	20	<1^‡	<1^‡	<1^‡
Estimated percentage of WNND cases	Not applicable	35-40	55-60	Unknown but may be 5-10^§
Acute clinical features	Abrupt onset of fever, headache, malaise, fatigue, anorexia and nausea	Symptoms of WNF, plus meningismus (nuchal rigidity, photo and phonophobia); CSF with pleocytosis; white blood cell count generally < 500 cells/mm³	Symptoms of WNF, plus encephalopathy (altered mental status, lethargy), and/or focal neurologic signs (weakness, cranial nerve palsies); movement disorders, including tremor, parkinsonism and ataxia, may be frequent	Acute onset of limb weakness or paralysis; weakness is typically asymmetric and abrupt; involved limbs typically are flaccid and areflexic; respiratory muscles may be involved; WNP may occur in the absence of fever or other features suggestive of WNV infection
Estimated case fatality rate	<1	<1	20	10-50

*Syndromes include WNF, West Nile meningitis, West Nile encephalitis and WNP.
^‡Overall, WNND represents 1% of human WNV infections.
^§WNP may occur in the context of any other manifestation of WNV infection or in isolation, without associated fever, meningitis, or encephalitis.
Modified with permission from reference 47.
WNF: West Nile fever; WNND: West Nile neuroinvasive disease; WNP: West Nile poliomyelitis.

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Systemic and Ophthalmic Manifestations of West Nile Virus Infection

Optic Neuritis

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