A detailed neuropathological assessment of a Western Australian case of Balamuthia mandrillaris amoebic encephalitis

Abstract

Balamuthia mandrillaris is a protist, amphizoic protozoan that is free-living in the soil. This amoebae can rarely cause cutaneous disease and an amoebic encephalitis, the time-course of which ranges from subacute to fulminant.1 A 76-year-old male presented with a 1 week history of fevers and rigors, progressing rapidly to weakness with confusion and a GCS of 13 but without localising neurological signs. MRI brain and spine reported diffuse parenchymal and leptomeningeal disease, most marked within the median frontal lobes, favouring an infective/ haemorrhagic meningoencephalitis. No causative microorganism was identified on ante mortem investigation. Despite broad spectrum antimicrobial therapies, the patient deteriorated clinically. Brain death occurred 10 days after the initial presentation and the case was referred to the State Coroner’s Office of WA. Post mortem examination diagnosed Balamuthia mandrillaris infection which was confirmed by PCR testing of brain tissue and cerebrospinal fluid. This report details the neuropathological distribution of parenchymal cerebral necrosis, associated with trophozoite and encysted amoebic forms, which suggests a haematogenous portal of entry for the protozoa into the brain. We present detailed neuropathology findings on the third case of Balamuthia mandrillaris encephalitis originating in Western Australia to be reported in the literature. 1.Siddiqui R, Khan NA. Balamuthia mandrillaris: morphology, biology and virulence. Trop Parasitol 2015; 5: 15–22.