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. 2019 May 17;68(11):1815-1822.
doi: 10.1093/cid/ciy813.

The Epidemiology and Clinical Features of Balamuthia mandrillaris Disease in the United States, 1974-2016

Jennifer R Cope  1 , Janet Landa  1   2 , Hannah Nethercut  1   3 , Sarah A Collier  1 , Carol Glaser  4 , Melanie Moser  5 , Raghuveer Puttagunta  1 , Jonathan S Yoder  1 , Ibne K Ali  1 , Sharon L Roy  6
Affiliations

The Epidemiology and Clinical Features of Balamuthia mandrillaris Disease in the United States, 1974-2016

Jennifer R Cope et al. Clin Infect Dis. .

Abstract

Background: 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. Initial entry of Balamuthia into the body is likely via the skin or lungs. To date, only individual case reports and small case series have been published.

Methods: The Centers for Disease Control and Prevention (CDC) maintains a free-living ameba (FLA) registry and laboratory. To be entered into the registry, a Balamuthia case must be laboratory-confirmed. Several sources were used to complete entries in the registry, including case report forms, CDC laboratory results, published case reports, and media information. SAS© version 9.3 software was used to calculate descriptive statistics and frequencies.

Results: We identified 109 case reports of Balamuthia disease between 1974 and 2016. Most (99%) had encephalitis. The median age was 36 years (range 4 months to 91 years). Males accounted for 68% of the case patients. California had the highest number of case reports, followed by Texas and Arizona. Hispanics constituted 55% for those with documented ethnicity. Exposure to soil was commonly reported. Among those with a known outcome, 90% of patients died.

Conclusions: Balamuthia disease in the United States is characterized by a highly fatal encephalitis that affects patients of all ages. Hispanics were disproportionately affected. The southwest region of the United States reported the most cases. Clinician awareness of Balamuthia as a cause of encephalitis might lead to earlier diagnosis and initiation of treatment, resulting in better outcomes.

Keywords: Balamuthia mandrillaris; free-living ameba; granulomatous amebic encephalitis.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts of interest.

Figures

Figure 1.
Figure 1.
Arrow denotes the year Balamuthia mandrillaris was first described as a human pathogen. Cases reported prior to 1990 were retrospectively diagnosed.
Figure 2.
Figure 2.
Balamuthia Cases by State, United States, 1974–2016* *Cases were classified on the basis of the state of exposure, if known, or by the state of residence or diagnosis, if state of exposure was not known.
See this image and copyright information in PMC

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