Unveiling the Unforeseen

This article presents a clinical problem-solving case of a 57-year-old woman with a history of kidney and pancreas transplantation who presented with altered mental status, fever, and progressive neurologic symptoms, including visual hallucinations, tremors, and unsteadiness. Despite initial broad differential diagnoses for encephalopathy in an immunocompromised patient, and a series of negative tests, a cerebrospinal fluid (CSF) PCR assay ultimately confirmed Powassan virus lineage II infection. The case highlights the diagnostic challenges in transplant recipients and emphasizes the importance of direct pathogen detection methods like PCR, especially when serologic tests may be unreliable due to immunosuppression. The article also discusses the clinical presentation, imaging findings, and management considerations for Powassan virus encephalitis, an orthoflavivirus transmitted by ticks. This case underscores the need for high clinical suspicion of Powassan virus infection in patients with encephalitis residing in or traveling to endemic areas, even outside typical tick seasons.

This article presents a clinical problem-solving case of a 57-year-old woman with a history of kidney and pancreas transplantation who presented with altered mental status, fever, and progressive neurologic symptoms, including visual hallucinations, tremors, and unsteadiness. Despite initial broad differential diagnoses for encephalopathy in an immunocompromised patient, and a series of negative tests, a cerebrospinal fluid (CSF) PCR assay ultimately confirmed Powassan virus lineage II infection. The case highlights the diagnostic challenges in transplant recipients and emphasizes the importance of direct pathogen detection methods like PCR, especially when serologic tests may be unreliable due to immunosuppression. The article also discusses the clinical presentation, imaging findings, and management considerations for Powassan virus encephalitis, an orthoflavivirus transmitted by ticks. This case underscores the need for high clinical suspicion of Powassan virus infection in patients with encephalitis residing in or traveling to endemic areas, even outside typical tick seasons.