West Nile virus encephalitis in a kidney transplant recipient: a case report and review of the literature.

West Nile virus (WNV) neuroinvasive disease is an uncommon but serious complication in solid organ transplant (SOT) recipients. We report the case of a 66‑year‑old kidney transplant recipient who developed encephalitis during the 2024 mosquito season in South Carolina. The patient presented with high‑grade fever and progressive altered mental status. Brain magnetic resonance imaging showed symmetric posterior fluid-attenuated inversion recovery hyperintensities, and tacrolimus‑associated posterior reversible encephalopathy syndrome was suspected. However, cerebrospinal fluid analysis revealed lymphocytic pleocytosis and was ultimately positive for WNV immunoglobulin M, immunoglobulin G, and polymerase chain reaction, confirming neuroinvasive infection. Immunosuppression was reduced, and a 5‑day course of intravenous immunoglobulin (IVIG) was administered. The patient's neurological status gradually improved; however, allograft function deteriorated, and long‑term hemodialysis became necessary. At 6‑month follow‑up, the patient remained on dialysis and was dependent on others for activities of daily living. This case highlights diagnostic challenges in immunosuppressed hosts, emphasizes the importance of vector-borne infection surveillance in SOT populations, and supports immunosuppression reduction with adjunctive IVIG as a reasonable therapeutic approach. Routine WNV screening of donors in endemic areas and patient education on mosquito avoidance may help mitigate risk.