Japan

The map above shows the geographic distribution of an important cause of childhood neurologic infection and disability. Mosquitoes are the main vectors, and the primary hosts are pigs and wading birds. In the most common presentation, after a 5 to 15 day incubation period, patients develop fever, rigor, and diarrhea. This is followed by headache, vomiting, and generalized weakness. Finally, there are mental status changes, focal neurologic deficits (paresis, plegia, cranial nerve palsies), and movement disorders. Many patients go into a coma and have respiratory failure. In children, seizures are very common and can be subtle - twitching of a digit, eye movement, or irregular breathing. Labs reflect a mild leukocytosis and hyponatremia. CSF studies show an elevated opening pressure, and thalamic lesions are seen on imaging.

Challenge: What's the disease?

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