Balamuthia mandrillaris
| Balamuthia mandrillaris | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | Amoebozoa |
| (unranked): | Discosea |
| Order: | Centramoebida |
| Family: | Balamuthiidae |
| Genus: |
Balamuthia Visvesvara et al., 1993 |
| Species: | B. mandrillaris |
| Binomial name | |
|
Balamuthia mandrillaris Visvesvara et al., 1993 |
|
Balamuthia mandrillaris is a free-living amoeba that is known to cause the deadly neurological condition known as granulomatous amoebic encephalitis (GAE).B. mandrillaris is found in the soil and was first discovered in 1986 in the brain of a baboon that died in the San Diego Wild Animal Park. B. mandrillaris can infect the body through skin wounds or by inhaling the dust containing Balamuthia.Balamuthia has not been definitively isolated in nature, but it is believed to be distributed throughout the temperate regions of the world. This is supported somewhat by the presence of antibodies to Balamuthia present in healthy individuals. The Balamuthia genus is named in honor of the late parasitologist William Balamuth (1914–1981) for his contributions to the studies of parasitic and free-living amoebas.
Balamuthia mandrillaris is a free-living, heterotrophic amoeba, consisting of a standard complement of organelles surrounded by a three-layered cell wall, and with an abnormally large cell nucleus. On average, a Balamuthia trophozoite is approximately 30 to 120 micrometres in diameter. The cysts fall approximately in this range as well.
Balamuthia's life cycle, like the Acanthamoeba, consists of a cystic stage and a trophozoite stage, both of which are infectious, and both of which can be identified as inclusions in the brain tissue on microscopic examination of brain biopsies performed on infected individuals. The trophozoite is pleomorphic and uninucleated, but binucleate forms are occasionally seen. Cysts are also uninucleated possessing three walls: an outer thin irregular ectocyst, an inner thick endocyst, and a middle amorphous fibrillar mesocyst.
Balamuthia mandrillaris is larger than human leukocytes therefore making phagocytosis impossible. Instead, the immune system attempts to contain them at the portal of entry by mounting a type IV hypersensitivity reaction. They may enter the body through the lower respiratory tract or through open wounds. Upon introduction, the amoeba may form a skin lesion, or may migrate to the brain, causing a condition known as granulomatous amoebic encephalitis, (GAE), which is usually fatal. This granulomatous feature is mostly seen in immunocompetent patients; immunocompromised individuals exhibit a "peri-vascular cuffing".Balamuthia-induced GAE can cause focal paralysis, seizures, and brainstem symptoms such as facial paralysis, difficulty swallowing, and double vision.
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