Epidemic Japanese B encephalitis combined with contactin-associated protein-like 2 antibody-positive autoimmune encephalitis: A case report

BACKGROUND: It is not uncommon to develop viral encephalitis. Epidemic Japanese B encephalitis infection combined with contactin-associated protein-like 2 (CASPR-2) antibody-positive autoimmune encephalitis has not been reported at present. In clinical work, we need to consider more options. CASE SUMMARY: A 32-year-old male worker presented with headache, fever and call-unresponsive presentation. Complete cranial magnetic resonance image showed symmetrical abnormal signals in bilateral medial temporal lobe, bilateral thalamus and basal ganglia. Improved lumbar puncture showed that cerebrospinal fluid protein and cell count increased significantly. Viral encephalitis was considered, and the patient's consciousness still increased rapidly after antiviral treatment. Further detection of Cerebrospinal fluid Japanese B encephalitis virus Polymerase Chain Reaction positive, serum autoimmune encephalitis antibody showed CASPR-2 antibody positive (1:320), the patient's condition gradually improved after plasma exchange treatment. 3 mo later, the serum CASPR-2 antibody was negative and the patient's condition was stable. CONCLUSION: This article reports the world’s first case of Epidemic Japanese B encephalitis infection combined with CASPR-2 antibody-positive autoimmune encephalitis, with a view to raising awareness.