[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Free-living amoebae](https://durgical.com/en/microbiology/groups/free-living-amoebae/) › Balamuthia mandrillaris (and Sappinia)

# Balamuthia mandrillaris (and Sappinia)

- Parasite
- For completeness

A soil amoeba that enters through skin wounds or the lungs and reaches the brain slowly. It often starts as a skin plaque on the face.

Updated Nov 13, 2026

Also called: Sappinia pedata, granulomatous amoebic encephalitis

## Quick facts

**Type**
Parasite · [Free-living amoebae](https://durgical.com/en/microbiology/groups/free-living-amoebae/)

**Gram / shape**
Pleomorphic trophozoite with long pseudopods

**Spread**
Soil or dust entering skin wounds

**Causes**
Granulomatous amoebic encephalitis · Sappinia

**Treatment**
Long multidrug combinations that may include pentamidine

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Life cycle
- In Colombia
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Balamuthia causes granulomatous amoebic encephalitis in healthy and immunosuppressed people.
- A painless facial plaque (nose, cheek) can come months before the brain disease.
- Diagnosis by biopsy with immunostaining or PCR; CSF rarely shows amoebae.
- Fatality is about 90%; treatment is a long multidrug combination including miltefosine.
- Sappinia: binucleate amoeba, one reported encephalitis case.

## At a glance

**Shape**
Pleomorphic trophozoite with long pseudopods; double-walled cyst like Acanthamoeba

**Family**
Balamuthiidae

**Type**
Free-living amoeba

**Stain**
H&E of biopsies; immunofluorescence or immunoperoxidase of tissue

**Size**
Trophozoite about 15 to 60 µm; cyst about 10 to 25 µm

## Morphology

- Trophozoite of variable shape with long branching pseudopods; usually one nucleus.
- Round cyst with two walls visible by light microscopy and no pores; hard to tell from Acanthamoeba without special tests.
- Sappinia: trophozoites and cysts with two nuclei pressed together.

## Transmission

- Soil or dust entering skin wounds, or inhalation into the lower airways.
- Spread through the blood to the brain.
- Rarely through an organ from an infected donor; otherwise not person to person.

**Reservoir:** Soil and dust; also isolated from water

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- It lives in soil as a trophozoite and forms cysts when conditions are unfavorable.
- Trophozoites, the infective form, enter through broken skin or the airways.
- They multiply in the skin or lungs and cause granulomatous lesions.
- They reach the brain through the blood and cross the blood-brain barrier.
- Trophozoites and cysts are both found in infected tissue.

## Virulence factors

- Binding to brain microvascular endothelium and crossing of the blood-brain barrier.
- Necrotizing, hemorrhagic vasculitis with granulomas (which may be poor in immunosuppressed patients).
- Cysts resist drugs and immune attack.

## Diseases it causes

- Granulomatous amoebic encephalitis: subacute to chronic, over weeks to months; fatal in about 9 of 10 cases. [Free-living amoeba infections (Naegleria meningoencephalitis, Acanthamoeba) →](https://durgical.com/en/conditions/free-living-amoeba-infections/)
- Cutaneous balamuthiasis: a painless, enlarging plaque, often on the central face (nose, cheek), that can precede brain disease by months. [Free-living amoeba infections (Naegleria meningoencephalitis, Acanthamoeba) →](https://durgical.com/en/conditions/free-living-amoeba-infections/)
- Sappinia: a single reported case of amoebic encephalitis in a healthy adult, with a brain mass that was removed and survival. [Free-living amoeba infections (Naegleria meningoencephalitis, Acanthamoeba) →](https://durgical.com/en/conditions/free-living-amoeba-infections/)

## Clinical picture

- Unlike Acanthamoeba, it also infects healthy children and adults.
- Most reports come from the Americas, especially Latin America; many Peruvian patients first had a facial plaque.
- Encephalitis: headache, fever, behavior change, focal deficits and seizures; imaging shows several ring-enhancing lesions that can look like tumor, tuberculosis or toxoplasmosis.

## Diagnosis

- Biopsy of skin or brain: amoebae (often around vessels) with granulomas; immunofluorescence or immunoperoxidase staining identifies the species.
- PCR and metagenomic sequencing at reference laboratories.
- Cerebrospinal fluid is usually non-specific (lymphocytes, high protein); amoebae are rarely seen there.
- Most cases are diagnosed late or at autopsy.

## Treatment

Long multidrug combinations that may include pentamidine, sulfadiazine, flucytosine, a mold-active azole, a macrolide (azithromycin or clarithromycin) and miltefosine; nitroxoline is investigational. Surgery of skin or brain lesions may help. A few survivors had early diagnosis.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Pentamidine](https://durgical.com/en/pharmacology/pentamidine/)
- [Sulfadiazine](https://durgical.com/en/pharmacology/sulfadiazine/)
- [Flucytosine](https://durgical.com/en/pharmacology/flucytosine/)
- [Voriconazole](https://durgical.com/en/pharmacology/voriconazole/)
- [Azithromycin](https://durgical.com/en/pharmacology/azithromycin/)
- [Miltefosine](https://durgical.com/en/pharmacology/miltefosine/)

## Prevention

- Cleaning and covering skin wounds contaminated with soil.
- Biopsy of a non-healing facial plaque in endemic areas.
- Screening of organ donors with unexplained encephalitis.

## In Colombia

Latin America, especially Peru, reports many of the world's cases; Balamuthia should be considered in Colombia in chronic facial plaques or encephalitis with ring lesions and negative tests for tuberculosis and toxoplasmosis.

## Memory aid

«The mandrill's mask»: Balamuthia was found in a mandrill and paints a plaque on the center of the face before it climbs to the brain.

## Test yourself

Think of the answer, then tap the question to see it.

## How does Balamuthia mandrillaris enter the body?

Through skin wounds contaminated with soil or by inhalation; then it reaches the brain through the blood.

## Which skin lesion can come before Balamuthia encephalitis?

A painless, enlarging plaque on the central face (nose or cheek).

## How does Balamuthia differ from Acanthamoeba in the hosts it infects?

Balamuthia also infects healthy children and adults; Acanthamoeba encephalitis is mostly in immunosuppressed people.

## What is the best way to confirm the diagnosis?

Tissue biopsy with immunofluorescence or immunoperoxidase staining, or PCR at a reference laboratory.

## What makes Sappinia trophozoites distinctive?

They have two nuclei pressed together.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/microbiology/balamuthia-mandrillaris/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 4

- [Acanthamoeba spp.](https://durgical.com/en/microbiology/acanthamoeba-spp/)
- [Naegleria fowleri](https://durgical.com/en/microbiology/naegleria-fowleri/)
- [Toxoplasma gondii](https://durgical.com/en/microbiology/toxoplasma-gondii/)
- [Mycobacterium tuberculosis](https://durgical.com/en/microbiology/mycobacterium-tuberculosis/)

## Related conditions 1

- [Free-living amoeba infections (Naegleria meningoencephalitis, Acanthamoeba)](https://durgical.com/en/conditions/free-living-amoeba-infections/)

[← Back to the group: Free-living amoebae](https://durgical.com/en/microbiology/groups/free-living-amoebae/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [CDC - DPDx - Free Living Amebic Infections](https://www.cdc.gov/dpdx/freelivingamebic/index.html) (CDC, 2024); [Balamuthia Infections | Balamuthia Infection | CDC](https://www.cdc.gov/balamuthia/about/index.html) (CDC, 2024); [Clinical Care of Balamuthia Infection | Balamuthia Infection | CDC](https://www.cdc.gov/balamuthia/hcp/clinical-care/index.html) (CDC, 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/balamuthia-mandrillaris/