A 62 year-old female is admitted with a 3-day history of malaise, fever, and myalgia. Five days ago, she flew back from the United States where she had spent 2 weeks travelling around the country. Over the next days, she developed cnfusion and seizures and eventually became comatose. CSF analysis showed 98 white cells per mm3 and a protein concentration of 0.88 g/L.  MRI T2 FLAIR of the brain is shown below. What is the most likely diagnosis?