Balamuthia mandrillaris is a free-living ameba that causes rare, nearly always fatal disease, in humans and animals worldwide. B. mandrillaris has been isolated from soil, dust, and water and likely spreads hematogenously to the CNS from the lungs and skin. Balamuthia causes three known diseases: granulomatous amebic encephalitis (GAE), disseminated, and cutaneous balamuthiasis. To date, only individual case reports and small case series have been published. We present the largest national clinical case series of Balamuthia disease in the United States.
The Centers for Disease Control and Prevention maintains a Free-Living Ameba Laboratory and registry. Only laboratory-confirmed Balamuthia cases are entered into the registry with additional sources used to assemble a complete record, including case report forms, laboratory results, published articles, and media information. Case reports were included in this analysis if the final diagnosis was GAE, disseminated, or cutaneous balamuthiasis. Microsoft Excel and SAS© software were used to calculate descriptive statistics.
A total of 94 cases of Balamuthia disease were reported between 1974–2014. Case-patient median age was 34 years (range 4 months to 91 years). Case-patients were mostly male (67%) and Hispanic (63% of those with documented ethnicity). Fever (35%), headache (32%), and vomiting (29%) were the most frequently reported initial symptoms while presenting neurologic symptoms included altered mental status (25%) and seizure (17%). The median CSF WBC count was 105 cells/µL with lymphocytic predominance. Abnormal brain imaging was found in 99% of patients, with 60% having enhancing lesions. Most (87%) had GAE without other organ involvement. Among those with a known outcome, case-fatality was 90%. Treatment for patients who survived (n=9) included some combination of a macrolide, fluconazole, flucytosine, pentamidine, and sulfadiazine.
Balamuthia disease in the U.S. has a nonspecific clinical presentation that typically develops into a highly fatal encephalitis that affects all ages. Based on few survivors, treatment should include multiple drugs. Balamuthia disease should be considered in the differential diagnosis of encephalitis.
J. Gomez, None
S. Collier, None
M. Moser, None
S. Roy, None
G. S. Visvesvara, None