Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content

Information for Public Health & Medical Professionals

Clinicians: For 24/7 diagnostic assistance, specimen collection guidance, shipping instructions, and treatment recommendations, please contact the CDC Emergency Operations Center at 770-488-7100.

Clinicians: CDC no longer provides miltefosine for treatment of free-living ameba infections. Miltefosine is now commercially available. Please visit for more information on obtaining miltefosine in the United States. If you have a patient with suspected free-living ameba infection, please contact the CDC Emergency Operations Center at 770-488-7100 to consult with a CDC expert regarding the use of this drug.

Balamuthia Infection: General Information

Balamuthia mandrillaris is a free-living ameba (a single-celled living organism) naturally found in the environment. Balamuthia can cause a rare and serious infection of the brain called granulomatous amebic encephalitis (GAE). Balamuthia can present with a local skin lesion, isolated neurologic disease, or disseminated disease affecting the skin, brain, and other organs 1.

The environmental niche of Balamuthia mandrillaris is not well defined. It has been isolated from soil and dust 2–4. It is possible that Balamuthia may also live in water 5–7. Exposure to Balamuthia might be common 8–10 although disease caused by Balamuthia is rare. Infection is thought to occur by inhalation of airborne cysts or through direct skin inoculation; GAE is thought to occur when organisms then travel from the lower respiratory tract, sinuses, or skin to the meninges and brain by the hematogenous route 11, although invasion of the olfactory neuroepithelium via the nasal route has also been postulated 12,13.

Since it was first described in 1989 14,15, over 200 cases of Balamuthia disease have been reported worldwide 16. There have been 94 Balamuthia cases reported to CDC during 1974–2014 in the U.S. (CDC unpublished data – these numbers include retrospectively identified cases after the identification of Balamuthia in 1989). Although cases reported in Latin America, Asia, and Australia occurred mostly in immunocompetent patients, some of the U.S. cases were immunocompromised individuals 7. For example, during 2009–2012, CDC identified three clusters of Balamuthia GAE transmitted by organ transplantation 17–19. Additionally, there seems to be a disproportionate involvement of patients of Hispanic ethnicity among the U.S. cases: at least 33% (29/88) of the U.S. case patients were Hispanic (CDC unpublished data).

  1. Schuster FL, Visvesvara GS. Free-living amoebae as opportunistic and non-opportunistic pathogens of humans and animals. Int J Parasitol. 2004;34:1001–27.
  2. Schuster FL, Dunnebacke TH, Booton GC, Yagi S, Kohlmeier CK, Glaser C, Vugia D, Bakardjiev A, Azimi P, Maddux-Gonzalez M, Martinez AJ, Visvesvara GS. Environmental isolation of Balamuthia associated with a case of amebic encephalitis. J Clin Microbiol. 2003;41:3175–80.
  3. Dunnebacke TH, Schuster FL, Yagi S, Booton GC. Balamuthia mandrillaris from soil samples. Microbiology. 2004;150:2837–42.
  4. Niyyati M, Lorenzo-Morales J, Rezaeian M, Martin-Navarro CM, Haghi AM, Maciver SK, Valladares B. Isolation of Balamuthia mandrillaris from urban dust, free of known infectious involvement. Parasitol Res. 2009;106(1):279–81.
  5. Finnin PJ, Visvesvara GS, Campbell BE, Fry DR, Gasser RB. Multifocal Balamuthia mandrillaris infection in a dog in Australia. Parasitol Res. 2007;100:423–6.
  6. Foreman O, Sykes J, Ball L, Yang N, De Cock H. Disseminated infection with Balamuthia mandrillaris in a dog. Vet Pathol. 2004;41:506–10.
  7. Bravo FG, Cabrera J, Gottuzo E, Visvesvara GS. Cutaneous manifestations of infection by free-living amebas. Tropical Dermatology. Tyring SK, Lupi O, Hengge UR, editors. Philadelphia: Elsevier. 2006.  pp. 49–55.
  8. Huang ZH, Ferrante A, Carter RF. Serum antibodies to Balamuthia mandrillaris, a free-living amoeba recently demonstrated to cause granulomatous amoebic encephalitis. J Infect Dis. 1999;179:1305–8.
  9. Schuster FL, Yagi S, Wilkins PP, Gavali S, Visvesvara GS, Glaser CA. Balamuthia mandrillaris, agent of amebic encephalitis: detection of serum antibodies and antigenic similarity of isolates by enzyme immunoassay. J Eukaryot Microbiol. 2008;55:313–20.
  10. Kiderlen AF, Radam E, Tata PS. Assessment of Balamuthia mandrillaris-specific serum antibody concentrations by flow cytometry. Parasitol Res. 2009;104:663-670.
  11. Visvesvara GS, Roy SL, Maguire JH. Pathogenic and Opportunistic Free-Living Amebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia pedata. Tropical Infectious Diseases—Principles, Pathogens, Practice, 3rd ed. Guerrant RL, Walker DH, Weller PF, editors. Philadelphia, PA: Elsevier Churchill Livingstone. 2001. p. 707–13.
  12. Matin A, Siddiqui R, Jayasekera S, Khan NA. Increasing importance of Balamuthia mandrillaris. Clin Microbiol Rev. 2008;21(3):435–48.
  13. Kiderlen AF, Laube U. Balamuthia mandrillaris, an opportunistic agent of granulomatous amebic encephalitis, infects the brain via the olfactory nerve pathway. Parasitol Res. 2004;94:49–52.
  14. Visvesvara GS, Martinez AJ, Schuster FL, Leitch GJ, Wallace SV, Sawyer TK, Anderson M. Leptomyxid ameba, a new agent of amebic meningoencephalitis in humans and animals. J Clin Microbiol. 1990;28:2750–2756.
  15. Visvesvara GS, Schuster FL, Martinez AJ. Balamuthia mandrillaris, N. G., N. Sp, agent of amebic meningoencephalitis in humans and other animals. J Eukaryot Microbiol. 1993;40:504–14.
  16. Perez MT, Bush LM. Balamuthia mandrillaris amebic encephalitis. Curr Infect Dis Rep. Jul 2007;9(4):323–8.
  17. CDC. Balamuthia mandrillaris transmitted through organ transplantation—Mississippi, 2009. MMWR Morb Mortal Wkly Rep. 2010;59:1165–70.
  18. CDC. Notes from the field: transplant-transmitted Balamuthia mandrillaris — Arizona, 2010. MMWR Morb Mortal Wkly Rep. 2010;59:1182.
  19. Gupte AA, Hocevar SN, Lea AS, Kulkarni RD, Schain DC, Casey MJ, Zendejas-Ruiz IR, Chung WK, Mbaeyi C, Roy SL, Visvesvara GS, da Silva AJ, Tallaj J, Eckhoff D, Baddley JW. Transmission of Balamuthia mandrillaris through solid organ transplantation: utility of organ recipient serology for guide clinical management. Am J Transplant. 2014;14:1417–24.