Encephalitis, Japanese/complications; Encephalitis/diagnosis; West Nile Fever/complications; Acute Disease; Adult; Anti-Infective Agents/therapeutic use; Brain/physiopathology; Brain/virology; Consciousness; Encephalitis/drug therapy; Encephalitis/physiopathology; Encephalitis Virus, Japanese/genetics; Encephalitis Virus, Japanese/immunology; Encephalitis Virus, Japanese/isolation & purification; Encephalitis, Japanese/diagnosis; Encephalitis, Japanese/drug therapy; Enzyme-Linked Immunosorbent Assay; Evidence-Based Practice; Fever; Follow-Up Studies; Humans; Immunoglobulin M/blood; Immunoglobulin M/cerebrospinal fluid; Lung/diagnostic imaging; Male; Metronidazole/therapeutic use; RNA, Viral/cerebrospinal fluid; Radiography; Reverse Transcriptase Polymerase Chain Reaction/methods; Roxithromycin/therapeutic use; Seizures; Syndrome; West Nile Fever/diagnosis; West Nile Fever/drug therapy; West Nile virus/immunology; West Nile virus/isolation & purification; West Nile virus/pathogenicity