My Brother-in-law Is A Veterinarian Who Went On A Mission

My brother-in-law is a veterinarian who went on a mission trip to Haiti to treat their animals. Now months later he has suddenly become paralyzed, in just a day's time. He is now in a hospital, and the numerous tests are coming back negative. He cannot move, except to talk. He is having difficulty swallowing. He cannot lift his head. Is it possible that it could be a parasite? What tests can be performed to determine if this is the case?