In Reply: Emergence of Pediatric West Nile Virus Neuroinvasive Disease in Spain: An Expanding Threat in a Changing Climate—A Case Series

To the Editors: We read with great interest the recent article in your April issue by Marín-Cruz et al1 addressing pediatric West Nile virus (WNV) neuroinvasive disease and the expanding clinical relevance of WNV infection in children. Their case series emphasizes that, although pediatric WNV neuroinvasive disease remains uncommon, it may cause severe neurologic morbidity and should be considered in children presenting with unexplained meningitis, encephalitis or acute flaccid paralysis during the transmission season. We would like to contribute by reporting an unusual pediatric neuro-ophthalmic presentation of WNV infection that further broadens this spectrum. A previously healthy 12-year-old girl was admitted with acute bilateral near-complete visual loss. Ophthalmologic examination revealed bilateral optic disc edema, with flame-shaped peripapillary hemorrhages around the right optic disc (Fig. 1A, B). Visual acuity was limited to counting fingers at 2 m in the right eye and light perception in the left eye. Orbital magnetic resonance imaging demonstrated bilateral optic nerve thickening and T2-hyperintensity extending through the intraorbital, intracanalicular and prechiasmatic segments, accompanied by posterior globe flattening and mild optic disc protrusion. Brain and spinal magnetic resonance imaging were otherwise unremarkable. Lumbar puncture showed an opening pressure of 30 cm-H2O. Extensive infectious and autoimmune investigations, including live-cell anti-aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies, were negative. Serum WNV immunoglobulin (Ig)M was positive, and subsequent WNV IgG seroconversion supported recent infection.FIGURE 1.: Initial presentation fundus photographs of the right (A) and left (B) eyes demonstrate marked bilateral optic disc edema with blurred disc margins, vascular congestion and peripapillary nerve fiber layer swelling; splinter hemorrhages are visible in the right eye. Three-month follow-up fundus photographs of the right (C) and left (D) eyes show resolution of optic disc edema, accompanied by the development of temporal optic disc pallor.Given the severity of visual loss and the extensive bilateral optic nerve involvement, high-dose intravenous methylprednisolone was initiated, followed by plasma exchange because of insufficient early response, and subsequently intravenous Ig. Visual function gradually improved over the following weeks, reaching 0.16 in the right eye and counting fingers at 2 m in the left eye at 3 weeks. Follow-up optical coherence tomography showed bilateral retinal nerve fiber layer thinning while follow-up fundus examination demonstrated mild temporal optic disc pallor (Fig. 1C, D). Monthly intravenous Ig was continued for 6 months. At the 6-month follow-up, visual acuity had improved to 0.9 in the right eye and 0.5 in the left eye. This case is notable for several reasons. First, optic nerve involvement is distinctly uncommon in WNV infection, and pediatric neuro-ophthalmic presentations are particularly rare.2 Second, unlike the more characteristic ocular manifestation of WNV—bilateral multifocal chorioretinitis—our patient presented with severe bilateral long-segment prechiasmatic optic neuritis without chorioretinal lesions.3 Third, the absence of prominent meningoencephalitic findings suggests that WNV-associated visual loss may occasionally reflect a predominantly optic nerve–centered inflammatory phenotype rather than classic neuroinvasive disease. As highlighted by Marín-Cruz et al,1 no specific antiviral therapy is currently available for WNV infection, and evidence supporting immunomodulatory treatment remains limited. Nevertheless, in selected vision-threatening presentations, early recognition and prompt escalation of immunotherapy may be clinically relevant. To our knowledge, this case represents the first pediatric neuro-ophthalmologic presentation of WNV infection reported from Turkey. We therefore suggest that WNV should be included in the differential diagnosis of acute bilateral optic neuritis or unexplained severe visual loss in children from endemic or recently affected regions, even when systemic or meningoencephalitic manifestations are absent.