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Trophozoites adhere to host epithelial cells via a specialized disk-shaped organelle called the ventral disk. [14] Cysts are oval-shaped cells slightly smaller than trophozoites. [15] They lack flagella, and are covered by a smooth, clear cyst wall. [15] Each cyst contains four nuclei and fragments of the ventral disc. [15]
Less common symptoms include vomiting and blood in the stool. [1] Symptoms usually begin one to three weeks after exposure and, without treatment, may last two to six weeks or longer. [4] Giardiasis usually spreads when Giardia duodenalis cysts within faeces contaminate food or water that is later consumed orally. [1]
Giardia (/ dʒ iː ˈ ɑːr d i ə / or / ˈ dʒ ɑːr d i ə /) is a genus of anaerobic flagellated protozoan parasites of the phylum Metamonada that colonise and reproduce in the small intestines of several vertebrates, causing the disease giardiasis. Their life cycle alternates between a swimming trophozoite and an infective, resistant cyst.
A diagnosis can only be definitively made after genetic testing to look for a mutation in the DOCK8 gene. However, it can be suspected with a high IgE level and eosinophilia. Other suggestive laboratory findings include decreased numbers of B cells, T cells, and NK cells; and hypergammaglobulinemia. [1]
Giardia duodenalis contains two functionally equivalent nuclei that are inherited independently during mitosis. In the giardial cyst these nuclei fuse and undergo homologous recombination facilitated by meiosis gene homologs. [9] The recombination associated with karyogamy may primarily function to repair DNA damage.
GATA2 deficiency is a grouping of several disorders caused by common defect, namely, familial or sporadic inactivating mutations in one of the two parental GATA2 genes. Because the gene is haploinsufficient, mutations that cause a reduction in cellular levels of the gene's product, GATA2, are autosomal dominant.
They include the retortamonads, diplomonads, parabasalids, oxymonads, and a range of more poorly studied taxa, most of which are free-living flagellates. All metamonads are anaerobic (many being aerotolerant anaerobes), and most members of the four groups listed above are symbiotes or parasites of animals, as is the case with Giardia lamblia ...
In both humans and mice, genes encoding the NKG2 family are clustered – in human genome on chromosome 12, in mouse on chromosome 6. [2] They are generally expressed on NK cells and a subset of CD8 + T cells, although the expression of NKG2D was also confirmed on γδ T cells, NKT cells, and even on some subsets of CD4 + T cells or myeloid cells.