A 38 year old man presents with generalized weakness and an unsteady gait for 1 day, in a background of anorexia, nausea and vomiting for 2 days. There was no history of fever, headache, or trauma.

Five days ago, he returned from a visit to Queensland, Australia, where he went hiking in the bush for several days.

His medical history is unremarkable. He is not on any drugs and denies substance abuse.