Balamuthia mandrillaris presenting as central nervous system vasculitis in a young child.

Balamuthia mandrillaris is a rare and difficult-to-diagnose infection with high mortality. We present the case of an immunocompetent toddler presenting with central nervous system (CNS) vasculitis. He was initially diagnosed with Takayasu arteritis and had an initial period of improvement following immunosuppressive therapy. Subsequently, he had rapid decompensation with diffuse intracranial lesions progressing to severe neurological injury and compassionate extubation. Metagenomic sequencing of the CSF and pathology and PCR from brain biopsy were positive for B. mandrillaris To our knowledge, this is the first case of Balamuthia presenting as a mixed vessel CNS vasculitis and highlights the importance of consideration of this infection in cases of vasculitis, particularly in mixed vessel disease. It further demonstrates the potential use of newer diagnostics, namely CSF metagenomic testing and amoeba PCR, in earlier diagnosis and treatment.