Japanese encephalitis (JE). The travel history was crucial in making the diagnosis which was confirmed by a greater than fourfold rise in the serum and CSF antibody titres. Another important clue to the diagnosis was the MR brain scan: abnormalities can occur in the thalami, basal ganglia, and midbrain.

JE is caused by a flavivirus, which is transmitted between birds and animals by Culex mosquitoes. Pigs are the most important natural host involved in the transmission to humans. JE occurs in rural areas in many parts of Asia, including China and Japan, but the affected areas appear to be expanding. …