Entamoeba polecki
From Wikipedia, the free encyclopedia
| Entamoeba polecki | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Phylum: | Amoebozoa |
| Family: | Entamoebidae |
| Genus: | Entamoeba |
| Species: | E. polecki |
| Binomial name | |
| Entamoeba polecki von Prowazek, 1912 | |
Entamoeba polecki is an intestinal parasite[1] of the genus Entamoeba. E. polecki is found primarily in pigs and monkeys and is largely considered non-pathogenic in humans, although there have been some reports regarding symptomatic infections of humans.[2] Prevalence is concentrated in New Guinea, with distribution also recorded in areas of southeast Asia, France, and the United States.[3][page needed]
Mature trophozoites of E. polecki are generally 10–20 μm in diameter. Trophozoites are irregularly shaped and possess pseudopodia for motility.[3] They have a single nucleus with a small central karyosome and finely dispersed peripheral chromatin, similar to that of Entamoeba histolytica[3]. Cytoplasmic contents are similar to other Entamoeba sp. and are usually granular and vacuolated.[3] Cysts of E. polecki are morphologically unique, containing only one nucleus, varyingly sized chromatoid bars, and a large inclusion mass.[3][4]
Transmission and life cycle
There are two stages in the life cycle of E. polecki.[2] The first is as a trophozoite, a vegetative stage that cannot survive in the environment.[2] The second is a cyst, where transmission of parasite is possible and provides protection to harsh external environments. Cysts are infective when ingested by another organism.[2] The cystic form of this protozoan has a diameter as small as 9.5 μm and as large as 17.5 μm. Morphologically, E. polecki is extremely similar to Entamoeba histolytica and Entamoeba hartmanni. [2]
Transmission follows a fecal-oral route. Infected feces with mature cysts are ingested where the cyst matures to the trophozoite in the gastrointestinal tract of the host. It is considered to be a zoonotic parasite, as close contact with infected swine have been reported to be the cause of E. polecki infections in humans.[5] Transmission to humans from consumption of pork is unlikely.[6] Recent studies suggest that different subspecies infect non-human primates and pigs, and close inhabitation between the two do not coincide with transmission.[7]