Japanese spotted fever with post-infectious encephalitis.

Area of Science:

• Infectious Diseases
• Neurology
• Microbiology

Background:

• Japanese spotted fever (JSF) is a rickettsial illness caused by *Rickettsia japonica*.
• Central nervous system (CNS) involvement in JSF is rare, with only five previous cases reported.
• This study details a unique case of JSF with significant neurological manifestations.

Observation:

• A 74-year-old male presented with fever, rash, and subsequent mental disturbances.
• Diagnosis of JSF was confirmed via polymerase chain reaction (PCR).
• Neurological symptoms included altered mental state and abnormal behavior.

Findings:

• Cerebrospinal fluid analysis, electroencephalography, and SPECT imaging indicated post-infectious encephalitis.
• The patient's neurological symptoms improved after treatment with intravenous immunoglobulin.
• This case highlights the potential for *Rickettsia japonica* to induce post-infectious CNS complications.

Implications:

• JSF should be considered in the differential diagnosis of febrile illnesses with rash and neurological symptoms.
• Prompt diagnosis and treatment of JSF are crucial to prevent or mitigate neurological sequelae.
• Further research is warranted to understand the pathogenesis of CNS involvement in JSF.