Amebic Meningoencephalitis & Keratitis

Introduction Definition Free-living amebae of the genera Naegleria, Acanthamoeba, and Balamuthia cause fatal diseases of the central nervous system (CNS) of humans.1-33 Naegleria fowleri causes an acute and fulminant primary amebic meningoencephalitis (PAM) in children and young adults with a history of exposure to fresh water leading to death within 5 to 10 days after the onset of symptoms.4-6,9,10,16,17,19,25,27,30,31,33,34 Balamuthia mandrillaris,2,3,7,8,19-22,24,26,28-31,35,36 and several species of Acanthamoeba (Acanthamoeba castellanii, Acanthamoeba culbertsoni, Acanthamoeba rhysodes, Acanthamoeba polyphaga, Acanthamoeba divionensis, Acanthamoeba healyi, and Acanthamoeba lenticulata) cause a chronic, and usually fatal, granulomatous amebic encephalitis (GAE) that may last for several weeks or months.1, 11,18,19,23,30,31,37-42Acanthamoeba sp also cause an eyesight threatening infection, acanthamoeba keratitis, in humans, especially in persons wearing contact lenses.12,15,17,19,30,31,40,43-52 Additionally, N. fowleri, Acanthamoeba sp, and B. mandrillaris also infect animals.12-17, 19,28-31, 53-58 Sappinia diploidea, another freeliving ameba identified in 200159 as an agent of meningitis, was reidentified recently as Sappinia pedata based on molecular analysis.60 So far there is only one case reported due to this ameba. Synonyms Naegleria aerobia and Naegleria invadens are not valid synonyms for N. fowleri. Balamuthia mandrillaris was previously known as leptomyxid ameba.