Epidemiology and Clinical Features of Balamuthia mandrillaris Infection, China

Balamuthia mandrillaris is a highly lethal free-living ameba that primarily affects the skin and central nervous system, manifesting clinically as chronic granulomatous lesions and granulomatous encephalitis. Once the central nervous system is involved, the mortality rate exceeds 90%. No standardized treatment regimen has yet been established. In this review, we summarized 66 cases reported from China. The median patient age was 36 years (range 10 months-77 years); 62.12% patients were male and 37.88% female. Fifty-five (83.33%) patients were immunocompetent. For 42 (63.64%) patients, initial symptoms were cutaneous manifestations; of those, central nervous system involvement subsequently developed in 25 (59.52%) patients. Twenty-four (36.36%) patients were hospitalized initially with encephalitis. Among the 63 patients with a known outcome, 43 (68.25%) succumbed to infection. For patients with cutaneous-only disease, the survival rate was 93.75%, whereas once the central nervous system was affected, mortality reached 96.00%.