''Balamuthia mandrillaris'' is a free-living
amoeba
An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...
that causes the rare but deadly neurological condition
granulomatous amoebic encephalitis (GAE). ''B. mandrillaris'' is a soil-dwelling amoeba and was first discovered in 1986 in the brain of a
mandrill
The mandrill (''Mandrillus sphinx'') is a large Old World monkey native to west central Africa. It is one of the most colorful mammals in the world, with red and blue skin on its face and posterior. The species is sexually dimorphic, as mal ...
that died in the
San Diego Wild Animal Park.
''B. mandrillaris'' can infect the body through open wounds or by inhalation. ''Balamuthia'' has been isolated in nature. It is believed to be distributed throughout the temperate regions of the world. This is supported somewhat by the detection of
antibodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of ...
to the
protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the e ...
in healthy individuals.
The generic name ''Balamuthia'' was given by
Govinda Visvesvara, after his mentor,
parasitologist William Balamuth, for his contributions to the study of amoebae. Visvesvara isolated and studied the pathogen for the first time in 1993.
Morphology
''B. mandrillaris'' is a free-living,
heterotroph
A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...
ic amoeba, consisting of a standard complement of
organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' th ...
s surrounded by a three-layered
cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...
(thought to be made of
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
), and with an abnormally large
cell nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, h ...
. On average, a ''Balamuthia'' trophozoite is about 30 to 120
μm
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...
in diameter. The cysts fall around this range, as well.
Life cycle
''Balamuthia''s lifecycle, like the ''
Acanthamoeba
''Acanthamoeba'' is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats.
''Acanthamoeba'' has two evolutive forms, the metabolically active trophozoite and a dormant, stress-resistant cyst. Trophozoites are ...
'', consists of a cystic stage and a non-flagellated trophozoite stage, both of which are infectious, and both of which can be identified in the brain tissue on microscopic examination of
brain biopsies performed on infected individuals. The trophozoite is pleomorphic and