A 30-year old patient presented with features of acute meningoencephalitis in the casualty. His CSF on wet mount microscopy revealed motile unicellular microorganisms. The most likely organism is ?

Ans. is 'a' i.e., Naegleria fowleri . Acute meninogoencephalitis and presence of motile unicellular organism in C.S.F. confirms the diagnosis of Naegleri fowleri. "Diagnosis depends on the detection of motile trophozoites in wet mount of fresh spinal fluid". Naegleria fowleri . It is a free living amoeba . Exists in three forms a) Amoeboid trophozoite b) Biflagellate trophozoite c) Cyst (Never forms in human body) . Modes of transmission - Human primarily contract infection by swimming in contaminated water. The amoeboid trophozoite enters the human body through nasal mucosa and migrates to brain along the olfactory nerve and blood vessels. - Some infections result by inhalation of cysts. . Clinical features (primary amoebic meningoencephilitis) - Common in young adults and children. - Incubation period 2 - 15 days (5 days) - Headache, high fever, nausea, vomiting, meningismus. - Cranial nerve palasies --> 3", 41th and 6th - Most patients die within a week (95%). - N. foweleri also causes humidifier fever a form of allergic alveolitis resulting from inhaling air from air -coolers. . Diagnosis - Detection of motile amoeboid trophozoites in wet mounts of C.S.F. . Treatment - High doses of amphotericin B and rifampicin. Acanthamoeba . It is a free living amaeba . Acanthamoeba culbesoni species is most common. . Exists in two stages a) Trophozoite b) Cyst . Flagellate stage is absent . Modes of transmission - Through contamination of traumatized skin or eye - Inhalation . C/Fs a) Granulomatous amoebic encephalitis (GAE) b) Keratitis (in contact lens users) . Diagnosis - Examination of CSF for trophozoites - Corneal scraping for cysts. . Treatment - No satisfactory treatment is available for GAE - For keratitis --> Neomycin, Propamide and dibromopropamide