Because encephalitis and meningitis can manifest in much the same way, it is easy to see why Ed was misdiagnosed. When a patient presents with symptoms that are manifest in multiple diseases/afflictions, it can be incredibly hard to tell. In this case, though, Chad has spoken to several trained medical personnel, who all said that it was potentially encephalitis, which is a semi-rare affliction. I think that this point, it is better to expect the worst and prepare for it, rather than pipe dream it to be less. Sorry, Millie, but you know that we want you to be prepared.