This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
A patient presents with headache, high fever and meningismus. Within 3 days he becomes unconscious. Most probable causative agent ? 
Select and explain. 
A. Naegleria fowleri, B. Acanthamoeba castellani, C. Entamoeba histolytica, D. Trypanosoma cruzi
A: Naegleria fowleri
Answer: A: Naegleria fowleri 
Explanation: Ans. is 'a' i.e., Naegleria fowleri Amongst the given options Naeglaria and Acanthamoeba cause amoebic encephalitis. "The prognosis of Naeglaria encephalitis is uniformaly poor, most patients die within a week". "Acanthamoeba encephalitis follows a more indolent course".