GRANULOMATOUS AMEBIC ENCEPHALITIS - A REVIEW AND REPORT OF A SPONTANEOUS CASE FROM VENEZUELA

Granulomatous amebic encephalitis (GAE), or meningoencephalitis due to Acanthamoeba spp. and leptomyxid ameba are uncommon CNS infections th at generally occur in immunocompromised hosts. We describe a case of G AE caused by Balamuthia mandrillaris previously designated as a leptom yxid ameba, in an apparently healthy 14-year-old Venezuelan boy. This case was characterized by sudden onset of seizures, focal neurologic s igns and by a prolonged clinical course (from November 1992 to March 1 993). Neuroimaging studies showed cerebral hypodense lesions in cerebr al hemispheres, brain stem and cerebellum. Microscopically, we found a chronic granulomatous inflammatory reaction with necrotizing angiitis , large numbers of amebic trophozoites and few cysts in perivascular s paces and within necrotic CNS tissue. The amebas were identified as B. mandrillaris based on their immunofluorescence reactivity with the an ti-B. mandrillaris serum. So far, 30 cases of GAE due to B. mandrillar is have been recognized in humans, two in AIDS patients. No visceral i nvolvement by free-living amebas or any other significant abnormality was observed. This patient developed ''spontaneous'' GAE, but it remai ns possible that an undiagnosed abnormality in cell-mediated immunity or a deficient humoral immune response may explain the susceptibility of this patient to this opportunistic infection.