Entamoeba moshkovskii

This species, morphologically identical to Entamoeba histolytica/dispar, was isolated in 1941 in the sewage of Moscow and is today considered a free-living amoeba occasionally hosted by man. Another amoeba species, Entamoeba histolytica Laredo strain (of which the name comes from the American town where the species was first isolated in man), has the same morphology as Entamoeba histolytica and is considered a non-pathogenic variant of the latter. In 1991, C.G. Clark and L.S. Diamond used molecular biological methods to demonstrate that the Laredo strain of Entamoeba histolytica is identical to Entamoeba moshkovskii.

Entamoeba moshkovskii has long been considered non-pathogenic to man, although recent data suggest that this amoeba may have a pathogenic role. It is impossible to morphologically distinguish trophozoites and cysts of Entamoeba moshkovskii from those of Entamoeba histolytica/dispar. In fact, the prevalence of Entamoeba moshkovskii was underestimated until the use of PCR and zymodeme analysis of cultured organisms permitted a more accurate identification of this species. The resulting increase in prevalence of this species confirms the hypothesis that man is a true host for this free-living amoeba. Entamoeba moshkovskii is easy to culture at room temperature, and this is the best criterion to differentiate this species from Entamoeba histolytica. An ELISA test for the identification of Entamoeba moshkovskii is not available yet.

For a description of the morphology of cysts and trophozoites of Entamoeba moshkovskii, see the preceding sections on Entamoeba histolytica and Entamoeba dispar.