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Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, aphasia, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.
Acanthamoeba is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats. The genus Acanthamoeba has two stages in its life cycle, the metabolically active trophozoite stage and a dormant, stress-resistant cyst stage. In nature, Acanthamoeba species are generally free-living bacterivores. However, they are also opportunistic pathogens able to cause serious and sometimes fatal infections in humans and other animals.
Free-living amoebae are a group of protozoa that are important causes of infectious disease in humans and animals.
Naegleriasis, also known as primary amoebic meningoencephalitis (PAM), is an almost invariably fatal infection of the brain by the free-living unicellular eukaryote Naegleria fowleri. Symptoms are meningitis-like and include headache, fever, nausea, vomiting, a stiff neck, confusion, hallucinations and seizures. Symptoms progress rapidly over around five days, and death usually results within one to two weeks of symptoms.
Naegleria is a genus consisting of 47 described species of protozoa often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flagellated stage, and has been routinely studied for its ease in change from amoeboid to flagellated stages. The Naegleria genera became famous when Naegleria fowleri, the causative agent of the usually fatal human and animal disease primary amoebic meningoencephalitis (PAM), was discovered in 1965. Most species in the genus, however, are incapable of causing disease.
Acanthamoeba keratitis (AK) is a rare disease in which amoebae of the genus Acanthamoeba invade the clear portion of the front (cornea) of the eye. It affects roughly 100 people in the United States each year. Acanthamoeba are protozoa found nearly ubiquitously in soil and water and can cause infections of the skin, eyes, and central nervous system.
Balamuthia mandrillaris is a free-living amoeba 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 that died in the San Diego Wild Animal Park.
Granulomatous amoebic encephalitis (GAE) is a rare, often fatal, subacute-to-chronic central nervous system disease caused by certain species of free-living amoebae of the genera Acanthamoeba, Balamuthia and Sappinia. The term is most commonly used with Acanthamoeba. In more modern references, the term "balamuthia amoebic encephalitis" (BAE) is commonly used when Balamuthia mandrillaris is the cause. Similarly, Sappinia amoebic encephalitis (SAE) is the name for amoebic encephalitis caused by species of Sappinia.
Miltefosine, sold under the trade name Impavido among others, is a medication mainly used to treat leishmaniasis and free-living amoeba infections such as Naegleria fowleri and Balamuthia mandrillaris. This includes the three forms of leishmaniasis: cutaneous, visceral and mucosal. It may be used with liposomal amphotericin B or paromomycin. It is taken by mouth.
Amoebiasis, or amoebic dysentery, is an infection of the intestines caused by a parasitic amoeba Entamoeba histolytica. Amoebiasis can be present with no, mild, or severe symptoms. Symptoms may include lethargy, loss of weight, colonic ulcerations, abdominal pain, diarrhea, or bloody diarrhea. Complications can include inflammation and ulceration of the colon with tissue death or perforation, which may result in peritonitis. Anemia may develop due to prolonged gastric bleeding.
Sappinia is a genus of heterotrophic, lobose amoebae within the family Thecamoebidae. A defining feature of Sappinia, which separates it from its sister genus Thecamoeba, is the presence of two closely apposed nuclei with a central, flattened connection. Sappinia species have two life cycle stages: a trophozoite and a cyst. Up until 2015, only two species had been discovered, Sappinia pedata and Sappinia diploidea. Sequencing of the small subunit rRNA of a particular isolate from a sycamore tree revealed a new species, Sappinia platani.Sappinia species were once thought to be coprozoic, as the first strains were isolated from animal dung. More research has shown that they are typical free-living amoebae, and can be found worldwide in soil, plant litter, and standing decaying plants, as well as freshwater ponds. In 2001, the first and only case of human pathogenesis in Sappinia was confirmed. The patient was a non-immunocompromised 38-year-old male who presented signs of amoebic encephalitis and who patient made a full recovery after treatment with several antimicrobials. The CDC initially classified the causative agent as S. diploidea based on morphological characteristics, but in 2009, Qvarnstrom et al. used molecular data to confirm that the true causative agent was S. pedata.
Cutaneous amoebiasis, refers to a form of amoebiasis that presents primarily in the skin. It can be caused by Acanthamoeba or Entamoeba histolytica. When associated with Acanthamoeba, it is also known as "cutaneous acanthamoebiasis". Balamuthia mandrillaris can also cause cutaneous amoebiasis, but can prove fatal if the amoeba enters the bloodstream It is characterized by ulcers. Diagnosis of amebiasis cutis calls for high degree of clinical suspicion. This needs to be backed with demonstration of trophozoites from lesions. Unless an early diagnosis can be made such patients can develop significant morbidity.
Acanthamoebidae is a family of single-celled eukaryotes within the group Amoebozoa.
Balamuthia infection is a cutaneous condition resulting from Balamuthia that may result in various skin lesions.
Sappinia pedata is a free living amoeboid organism, first described by Pierre Augustin Dangeard in 1896. It belongs to the genus Sappinia within the Thecamoebida clade of Amoebozoa and is characterized by its unique monopodial locomotion and cell surface morphology. S. pedata has been found in various habitats worldwide, mostly on herbivore dung, decaying plant matter, and soil. The species has gained attention due to its potential medical relevance and has been the subject of most recent and emerging studies in Protistology and Eukaryotic Microbiology as a whole.
Parachlamydia acanthamoebae are bacterium that fall into the category of host-associated microorganisms. This bacterium lives within free-living amoebae that are an intricate part of their reproduction. Originally named Candidatus Parachlamydia acanthamoebae, its current scientific name was introduced shortly after. This species has shown to have over eighty percent 16S rRNA gene sequencing identity with the class Chlamydiia. Parachlamydia acanthamoebae has the same family as the genus Neochlamydia with which it shares many similarities.
An amoeba, often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.
Naegleria fowleri, also known as the brain-eating amoeba, is a species of the genus Naegleria. It belongs to the phylum Percolozoa and is classified as an amoeboflagellate excavate, an organism capable of behaving as both an amoeba and a flagellate. This free-living microorganism primarily feeds on bacteria but can become pathogenic in humans, causing an extremely rare, sudden, severe, and almost always fatal brain infection known as naegleriasis or primary amoebic meningoencephalitis (PAM).
Amoebic encephalitis or amoebic meningoencephalitis may refer to several potentially fatal diseases that are infections of the central nervous system by free-living amoebae, often referred to in the media as a "brain-eating amoeba" infection:
Amoebozoa of the free living genus Acanthamoeba and the social amoeba genus Dictyostelium are single celled eukaryotic organisms that feed on bacteria, fungi, and algae through phagocytosis, with digestion occurring in phagolysosomes. Amoebozoa are present in most terrestrial ecosystems including soil and freshwater. Amoebozoa contain a vast array of symbionts that range from transient to permanent infections, confer a range of effects from mutualistic to pathogenic, and can act as environmental reservoirs for animal pathogenic bacteria. As single celled phagocytic organisms, amoebas simulate the function and environment of immune cells like macrophages, and as such their interactions with bacteria and other microbes are of great importance in understanding functions of the human immune system, as well as understanding how microbiomes can originate in eukaryotic organisms.
References
- ↑ Visvesvara GS; Moura H; Schuster FL (June 2007). "Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia diploidea". FEMS Immunol. Med. Microbiol. 50 (1): 1–26. doi:10.1111/j.1574-695X.2007.00232.x. PMID 17428307.
- 1 2 3 Brown; J.D. Silberman; F.W. Spiegel (2007). "Amoeba at attention: phylogenetic affinity of Sappinia pedata". J Eukaryot Microbiol. 54 (6): 511–9. doi:10.1111/j.1550-7408.2007.00292.x. PMID 18070328. S2CID 45094015 . Retrieved 8 December 2011.
- ↑ "Acanthamoeba: Overview - eMedicine" . Retrieved 2009-01-11.
- ↑ Gelman BB, Rauf SJ, Nader R, et al. (May 2001). "Amoebic encephalitis due to Sappinia diploidea". JAMA. 285 (19): 2450–1. doi:10.1001/jama.285.19.2450. PMID 11368696.
- ↑ Wylezich, C.; Walochnik, J.; Michel, R. (2009). "High genetic diversity of Sappinia-like strains (Amoebozoa, Thecamoebidae) revealed by SSU rRNA investigations". Parasitology Research. 105 (3): 869–873. doi:10.1007/s00436-009-1482-1. PMID 19495795. S2CID 28942657.
- ↑ Gelman, B.B. "Parasites-Sappinia". Amoebic encephalitis due to Sappinia diploidea. JAMA, 2001. Retrieved 8 December 2011.
- ↑ Gelman BB, Popov V, Chaljub G, et al. (October 2003). "Neuropathological and ultrastructural features of amebic encephalitis caused by Sappinia diploidea". J. Neuropathol. Exp. Neurol. 62 (10): 990–8. doi:10.1093/jnen/62.10.990. PMID 14575235.
- ↑ Marciano‐Cabral F (2009). "Free‐Living Amoebae as Agents of Human Infection". J Infect Dis. 199 (8): 1104–1106. doi:10.1086/597474. PMID 19302009.
