Infectious (IE) and autoimmune (AE) encephalitis have similar clinical presentations, making diagnosis and management challenging, particularly in resource-limited settings. There is evidence that involuntary movements, memory deficits, elevated cerebrospinal fluid (CSF) protein levels, and hippocampal lesions were more associated with AE. At the same time, fever, vomiting, respiratory symptoms, and CSF pleocytosis favor a diagnosis of IE.

Retrospective data from electronic medical records of adult patients with IE and AE admitted to the two institutions between January 2017 and May 2024 were collected, including clinical presentation, blood tests, CSF parameters, neuroimaging findings, and EEG results. Descriptive and analytical statistics were used to compare and differentiate between the two groups.  

Between January 2017 and May 2024, 97 patients presented with symptoms consistent with encephalitis, and all underwent lumbar puncture. Among them, 29 (29.9%), had laboratory-confirmed infection, with varicella zoster virus (n=8) being the most prevalent. Six (6%) patients tested positive for an autoantibody with Anti-NMDAR (n=4) as the most common. Patients with AE were younger (p=0.046), while a history of exposure to respiratory infections was more frequent in those with IE (p=0.003). In terms of clinical manifestations, seizures (p=0.004) and speech disturbances (p=0.001) were more common in AE, whereas headaches were more common in IE (p=0.005). The rest of the CSF and serum parameters, neuroimaging findings, and EEG results were similar in both groups.