infectious diseases
Granulomatous Amebic Encephalitis
Introduction
Granulomatous amebic encephalitis is a very rare, generally fatal subacute central nervous system (CNS) infection caused byAcanthamoebaspecies in immunocompromised or debilitated hosts or byBalamuthia mandrillaris. Acanthamoebaspecies andBalamuthia mandrillarisare present worldwide in water, soil, and dust. Human exposure is common, but infection is rare.Acanthamoebainfection of the CNS occurs almost entirely in immunocompromised or otherwise debilitated patients, butB. mandrillarismay also infect healthy hosts.Sappinia pedatawas implicated in one case of amebic encephalitis in Texas. The life cycle ofAcanthamoeba,Balamuthia, andSappiniainvolves only 2 stages: cysts and trophozoites (the infective form). The trophozoites form double-walled cysts, which resist eradication. The entry portal is thought to be the skin or lower respiratory tract, with subsequent hematogenous dissemination to the CNS. In infected patients, cysts and trophozoites may be found in tissues. 