Elucidation of the life cycle of the intestinal protozoanBlastocystis hominis

Abstract

This paper elucidates the status of the different morphological forms of Blastocystis and reports the existence of thin- and thick-walled cysts in B. hominis on the basis of current experimental evidence. It is suggested that the thin-walled cysts are autoinfectious, leading to multiplication of the organism in the intestinal tract. The thick-walled cysts are responsible for external transmission via the faecal-oral route. A life cycle for B. hominis is postulated on the basis of these findings.

New Insights on Classification, Identification, and Clinical Relevance of Blastocystis spp

“…Certain amphibian isolates possess thick cytoplasmic rims, which are easily discernible by conventional light microscopy (219 (302), suggesting a storage role for the organelle. The vacuole has also been suggested to play a role in schizogony-like reproduction (220,241) by providing an environment for the development of minute parasite progeny. This is highly unlikely considering that these progeny appear strikingly similar to metabolic granules described previously and are therefore simply variants of the granular form (257,290).…”

“…The intracellular granules are heterogeneous and have been described as being myelin-like inclusions, small vesicles, crystalline granules, and lipid droplets (65). Reproductive granules within the central vacuole have been described and have been reported to function in schizogony-like division (220,241,319). Other authors argued that this cannot be accepted due to the lack of evidence that these granules are indeed viable and develop into Blastocystis cells (33,233,257,290).…”

Extreme anoxia tolerance in embryos of the annual killifishAustrofundulus limnaeus: insights from a metabolomics analysis

“…Numerous conflicting life cycles have been proposed (33,217,220,233,250,319,321), and these discrepancies are due largely to the belief that Blastocystis exhibits multiple reproductive processes (83,220,318). The suggestion that Blastocystis undergoes multiple fission has led to life cycles where schizogony is one of the modes of reproduction (220,319).…”

Frecuencia y fuentes de Blastocystis sp. en niños urbanos de 0 a 5 años de hogares infantiles del estado del municipio de Calarcá, Colombia

“…ha tenido una historia controversial en cuanto a su capacidad patógena, pues no se ha establecido con claridad si es un patógeno, un microorganismo comensal o un oportunista, ya que en diversos estudios no se han encontrado diferencias significativas entre pacientes sintomáticos y asintomáticos (1,3). Es el parásito intestinal humano de mayor prevalencia, particularmente en países en desarrollo (1 (3,8,(11)(12)(13)(14)(15)(16)(17). En la población general en Colombia, se han informado frecuencias que fluctúan entre 25 % en Suaita, Santander, en el 2002 (18), y 62,6 % en Santa Marta, Magdalena, en el 2004 (19), en tanto que en niños de 5 a 12 años en Bogotá se reportó 22,4 % en el 2010 (20).…”