Supplementary Material for: A Case Report of Presumed West Nile Virus Chorioretinitis in a Non-Endemic Area Atypical Serology and Imaging Features of Old and New Lesions

West Nile virus (WNV) infection is a recognized cause of neuroinvasive disease and chorioretinitis, typically reported in endemic regions and often associated with positive IgM serology. We report a case of presumed bilateral WNV chorioretinitis associated with encephalitis in a non-endemic area, presenting with atypical serological findings. A 58-year-old woman developed acute encephalitis and bilateral panuveitis shortly after travel, with positive WNV IgG and negative IgM in serum and cerebrospinal fluid. Multimodal retinal imaging revealed the coexistence of inactive-appearing chorioretinal scars and active full-thickness retinitis, with characteristic wedge-shaped and linear lesion patterns. Fundus autofluorescence, fluorescein angiography, indocyanine green angiography, and optical coherence tomography helped differentiate lesions with different morphologic appearances and stages of activity. Although these findings do not prove viral relapse or reactivation, they raise the possibility of prior infection with subsequent delayed or recurrent ocular/CNS involvement. Systemic and topical corticosteroid therapy led to rapid clinical and imaging improvement. This case highlights the diagnostic value of multimodal imaging in suspected WNV chorioretinitis, underscores the limitations of serology alone, and supports cautious interpretation of atypical presentations in non-endemic settings.