A 22-year-old man develops fulminant meningoencephalitis 5 days after swimming in a warm freshwater lake. Motile trophozoites are seen in wet mount of CSF. Which organism is the most likely cause?
- A Naegleria fowleri ✓
- B Entamoeba histolytica
- C Acanthamoeba species
- D Balamuthia mandrillaris
Correct answer: A. Naegleria fowleri
Explanation
Naegleria fowleri, the 'brain-eating amoeba,' causes primary amebic meningoencephalitis (PAM) after nasal exposure to warm freshwater. It progresses rapidly and is usually fatal. CSF wet mount shows motile trophozoites. Acanthamoeba and Balamuthia cause granulomatous amebic encephalitis (GAE) in immunocompromised patients with a subacute course. Entamoeba histolytica does not cause meningoencephalitis.
Reference: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.