Primary amoebic meningitis caused by -

Naegleria fowleri, the only pathogenic species of naegleria Human infection comes from water containing the amoebae and usually follows swimming or diving in ponds. Patients are mostly previously healthy young adults or children. The amoebae invade the nasal mucosa, pass through the olfactory nerve branches in the cribriform plate into the meninges and brain to initiate an acute purulent meningitis and encephalitis (primary amoebic meningoencephalitis). The incubation period is 2 days to 2 weeks. The disease almost always ends fatally within a week TEXTBOOK OF MEDICAL PARASITOLOGY,CKJ PANIKER,6TH EDITION,PAGE NO 31