A Rare Case of Fatal Balamuthia mandrillaris Encephalitis in a Pediatric Patient: Diagnostic Challenges

Balamuthia mandrillaris is a rare and lethal amoeba that causes granulomatous amoebic encephalitis (GAE), a severe brain infection with a high mortality rate. This manuscript presents a case study of a 5-year-old female patient with B. mandrillaris amoebic encephalitis. She presented from an outside hospital (OSH) with daily fevers, fatigue, and worsening mental status. She was without comorbidities, and sick contacts were denied. Diagnosis was challenging due to nonspecific encephalitis symptoms and nonspecific neurological imaging. Neuroimaging revealed symmetric diffuse restriction in the medial aspect of the basal ganglia. Autoimmune antibody testing was unrevealing. Amoebic encephalitis was considered when exhaustive testing was negative. Treatment with antiamoebic agents was initiated while free-living amoebic PCR panel was pending. The diagnosis was confirmed through PCR testing on cerebrospinal fluid (CSF), highlighting the importance of molecular techniques in diagnosing B. mandrillaris infections. After confirmation, treatment was updated per CDC recommendations. However, her condition continued to worsen, with progression of hemorrhage, ventriculomegaly, and ultimately herniation. Unfortunately, devastating neurological damage to the brainstem had already occurred, leading to brain death. Early recognition and accurate diagnosis are crucial for timely treatment and prevention of mortality by B. mandrillaris encephalitis. The application of molecular techniques offers promising advancements in this field.