A patient presents with a headache, high fever and meningismus. Within 3 days he becomes unconscious. Most probable causative agent-
Ans, is 'a' i.e., Naegleria fowleri o Amongst the given options Naegleria and Acanthamoeba cause amoebic encephalitis. "The prognosis of Naeglaria encephalitis is uniformly poor, most patients die within a week" -------Harrison "Acanthamoeba encephalitis follows a more indolent course".--------Harrison o So, amongst the given options Naeglaria causes most fatal amoebic encephalitis. Naegleria fowleri o It is a free-living amoeba o Exists in three forms Amoeboid trophozoite Biflagellate trophozoite Cyst (Never forms in the human body) o Modes of transmission Human primarily contract infection by swimming in contaminated water. The amoeboid trophozoite enters the human body through the nasal mucosa and migrates to the brain along the olfactory nerve and blood vessels. Some infections result from inhalation of cysts. o Clinical features (primary amebic meningoencephalitis) Common in young adults and children. Incubation period ->2-15 days (5 days) A headache, high fever, nausea, vomiting, meningismus. Cranial nerve palsies -->> 3rd.4* and 6th Most patients die within a week (95%). N. fowleri also causes humidifier fever a form of allergic alveolitis resulting from inhaling air from air -coolers, o Diagnosis Detection of motile amoeboid trophozoites in wet mounts of C.S.F. o Treatment High doses of amphotericin B and rifampicin. Acanthamoeba o It is a free-living amoeba o Acanthamoeba culbertsoni species is most common, o Exists in two stages Trophozoite Cyst o The flagellate stage is absent o Modes of transmission Through contamination of traumatized skin or eye Inhalation o C.'Fs Granulomatous amoebic encephalitis (GAE) Keratitis (in contact lens users) o Diagnosis Examination of CSF for trophozoites Corneal scraping for cysts, o Treatment No satisfactory treatment is available for GAE For keratitis - Neomycin, Propenamide
Naegleria fowleri
Acanthamoeba castellani
Entamoeba histolytica
Trypanosoma cruzi
Parasitology