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Free Living Amebic Infections

[Acanthamoeba spp.] [Balamuthia mandrillaris] [Naegleria fowleri] [Sappinia spp.]

Treatment Information


Early diagnosis is essential for effective treatment of Acanthamoeba keratitis. Several prescription eye medications are available for treatment. However, the infection can be difficult to treat. The best treatment regimen for each patient should be determined by an eye doctor. If you suspect your eye may be infected with Acanthamoeba, see an eye doctor immediately.

Skin infections that are caused by Acanthamoeba but have not spread to the central nervous system can be successfully treated. Because this is a serious infection and the people affected typically have weakened immune systems, early diagnosis offers the best chance at cure.

Most cases of brain and spinal cord infection with Acanthamoeba (Granulomatous Amebic Encephalitis) are fatal.

Balamuthia mandrillaris

Although there have been more than 200 cases of Balamuthia infection worldwide, few patients are known to have survived as a result of successful drug treatment[1,2]. Early diagnosis and treatment might increase the chances for survival[3].

Drugs used in treating Granulomatous Amebic Encephalitis (GAE) caused by Balamuthia have included a combination of flucytosine, pentamidine, fluconazole, sulfadiazine and either azithromycin or clarithromycin[1,2,4,5]. Recently, miltefosine in combination with some of these other drugs has shown some promise[2]. Much more information is needed in treating patients with GAE due to Balamuthia.

  1. Perez MT, Bush LM. Balamuthia mandrillaris amebic encephalitis. Curr Infect Dis Rep. Jul 2007;9(4):323-328.
  2. Martinez DY, Seas C, Bravo F, et al. Successful treatment of Balamuthia mandrillaris amoebic infection with extensive neurological and cutaneous involvement. Clin Infect Dis. Jul 15 2010;51(2):e7-11.
  3. Siddiqui R, Khan NA. Balamuthia amoebic encephalitis: an emerging disease with fatal consequences. Microb Pathog. Feb 2008;44(2):89-97.
  4. Cary LC, Maul E, Potter C, et al. Balamuthia mandrillaris meningoencephalitis: survival of a pediatric patient. Pediatrics. Mar 2010;125(3):e699-703.
  5. Drugs for Parasitic Infections: The Medical Letter; 2010.

Naegleria fowleri

Although most cases of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri infection in the United States have been fatal (122/123 in the U.S., [1]), there have been two well-documented survivors in North America: one in California [2, 3] and one in Mexico [4]. It has been suggested that the survivor’s strain of Naegleria fowleri was less virulent, which contributed to the patient’s recovery. In laboratory experiments, the California survivor’s strain did not cause damage to cells as rapidly as other strains, suggesting that it is less virulent than strains recovered from other fatal infections [5].

Multiple patients have received treatment similar to the California survivor, including amphotericin B, miconazole/fluconazole/ketoconazole, and/or rifampin but only the patient in Mexico has survived making it difficult to determine the efficacy of the treatment regimen.

The survivors received the following medications:

Survivor Medications
U.S. California Survivor [2, 3] (1978) Mexico Survivor [4] (2003)
Amphotericin B Amphotericin B
Rifampicin Rifampicin
Miconazole – no longer available in US Fluconazole
Dexamethasone Dexamethasone
Sulfisoxazole (IV) – discontinued after Naegleria diagnosed Ceftriaxone

Recently an investigational breast cancer and anti-leishmania drug, miltefosine [6], has shown some promise in combination with some of these other drugs. Miltefosine has shown ameba-killing activity against free-living amebae, including Naegleria fowleri, in the laboratory [7, 8]. Miltefosine has also been used to successfully treat patients infected with Balamuthia [9] and disseminated Acanthamoeba infection [10]. CDC now has a supply of miltefosine for treatment of Naegleria fowleri infection [11]. If you are a clinician and have a patient with suspected Naegleria or other 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.


Treatment for the one identified case of Sappinia infection included the removal of a tumor in the brain and a series of drugs given to the patient after surgery. This treatment lead to the patient’s full recovery[1,2].

  1. Gelman, B.B., et al., Amoebic encephalitis due to Sappinia diploidea. JAMA, 2001. 285(19): p. 2450-1.
  2. Gelman, B.B., et al., Neuropathological and ultrastructural features of amebic encephalitis caused by Sappinia diploidea. J Neuropathol Exp Neurol, 2003. 62(10): p. 990-8.


  1. Yoder JS, Eddy BA, Visvesvara GS, Capewell L, Beach MJ. The epidemiology of primary amoebic meningoencephalitis in the USA, 1962-2008. Epidemiol Infect. 2010;138:968-75.
  2. Seidel JS, Harmatz P, Visvesvara GS, Cohen A, Edwards J, Turner J. Successful treatment of primary amebic meningoencephalitis. N Engl J Med. 1982;306:346-8.
  3. Visvesvara GS, Moura H, Schuster FL. Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia diploidea. FEMS Immunol Med Microbiol. 2007;50:1-26.
  4. Vargas-Zepeda J, Gomez-Alcala AV, Vasquez-Morales JA, Licea-Amaya L, De Jonckheere JF, Lores-Villa F. Successful treatment of Naegleria PAM using IV amphotericin B, fluconazole, and rifampin. Arch Med Res. 2005;36:83-6.
  5. John DT, John RA. Cytopathogenicity of Naegleria fowleri in mammalian cell cultures. Parasitol Res. 1989;76:20-5.
  6. Kaminsky R. Miltefosine Zentaris. Curr Opin Investig Drugs. 2002;3:550-4.
  7. Schuster FL, Guglielmo BJ, Visvesvara GS. In-vitro activity of miltefosine and voriconazole on clinical isolates of free-living amebas: Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri. J Eukaryot Microbiol. 2006;53:121-6.
  8. Kim JH, Jung SY, Lee YJ, Song KJ, Kwon D, Kim K, Park S, Im KI, Shin HJ. Effect of therapeutic chemical agents in vitro and on experimental meningoencephalitis due to Naegleria fowleri. [PDF - 7 pages] Antimicrob Agents Chemother. 2008;52:4010-16.
  9. Martínez DY, Seas C, Bravo F, Legua P, Ramos C, Cabello AM, Gotuzzo E. Successful treatment of Balamuthia mandrillaris amoebic infection with extensive neurological and cutaneous involvement. Clin Infect Dis. 2010;51:e7-11.
  10. Aichelburg AC, Walochnik J, Assadian O, Prosch H, Steuer A, Perneczky G, Visvesvara GS, Aspöck H, Vetter N. Successful treatment of disseminated Acanthamoeba sp. infection with miltefosine. [PDF - 4 pages] Emerg Infect Dis. 2008;14:1743-6.
  11. CDC. Investigational Drug Available Directly from CDC for the Treatment of Infections with Free-Living Amebae. MMWR Morb Mortal Wkly Rep. 2013;62(33):666.

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This information is provided as an informational resource for licensed health care providers as guidance only. It is not intended as a substitute for professional judgment.

For questions about DPDx, contact us
  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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