Encephalitis due to a free-living amoeba (Balamuthia mandrillaris): case report with literature review

Amebic infections can spread to the central nervous system with a lengthy but usually fatal course. A typical case is presented to raise awareness of this increasingly reported infectious process that may have a more favorable outcome if diagnosed in its early stages.

A 38-year-old male presented with an ulcerating 10 x 8 cm mass on his thigh and smaller skin nodules. In less than 6 months seizures developed due to granulomatous lesions of the brain. Biopsies/excisions of the thigh lesion, a subcutaneous nodule, and a brain lesion were performed. He failed to respond to broad spectrum antibiotics and antineoplastic agents, and died within 6 weeks of the initial MRI scan of the brain. Rare amebic trophozoites were appreciated in the biopsy specimens on post-mortem review, and Balamuthia mandrillaris confirmed as the infecting agent on immunofluorescence studies.

Granulomatous amebic encephalitis is a parasitic infection with a lengthy clinical course before rapid deterioration due to extensive brain lesions is noted. Either early treatment with antimicrobials or-in rare cases-excision of the brain lesion(s) may offer the chance of a cure.