Novel Entamoeba Findings in Nonhuman Primates

Abstract

In addition to well-known human-infecting species, Entamoeba species not found in humans have been identified recently in nonhuman primates (NHPs). Importantly, it has become clear that the organism identified as Entamoeba histolytica in NHPs is usually a distinct species, Entamoeba nuttalli. Many DNA-based stool surveys use species-specific detection methods and so may miss the full range of Entamoeba species present. In addition, authors may be using the same species name to describe distinct organisms. These various shortcomings may not be obvious to readers. In this review, we clarify the relationships between Entamoeba species' names based on morphological and molecular data, and highlight gaps in recently published data on Entamoeba species in wild NHPs resulting from the use of variable methodology.

Prevalence and Genetic Identification of Three Entamoeba Species in Pigs in Southeastern China

“…However, several distinct Entamoeba spp. with similar morphological characteristics (for instance, the E. dispar , a nonpathogenic species, is morphologically identical to E. histolytica ) cannot be distinguished by microscopic examination alone [1, 2, 4, 7]. Therefore, accurate identification of species/subtypes of Entamoeba was performed with molecular tools including PCR and nucleotide sequencing [1, 7, 12, 19, 23, 24].…”

“…The genus Entamoeba comprises many free-living and parasitic species and can infect all classes of vertebrates and some invertebrates. Some Entamoeba species (e.g., E. histolytica , E. dispar , E. coli , E. moshkovskii , E. hartmanni , and E. polecki ) have been identified in humans [1–4], and most are considered harmless, but some of these species still cause disease. Amoebiasis caused by E. histolytica is the third leading parasitic disease causing morbidity and mortality in humans, causing up to 50, 000 deaths per year, just behind malaria and schistosomiasis [4–7].…”

“…Some Entamoeba species (e.g., E. histolytica , E. dispar , E. coli , E. moshkovskii , E. hartmanni , and E. polecki ) have been identified in humans [1–4], and most are considered harmless, but some of these species still cause disease. Amoebiasis caused by E. histolytica is the third leading parasitic disease causing morbidity and mortality in humans, causing up to 50, 000 deaths per year, just behind malaria and schistosomiasis [4–7]. The disease is characterized as amebic colitis and liver abscess in humans and animals [3, 8].…”

Discrimination Experiments in Entamoeba and Evidence from Other Protists Suggest Pathogenic Amebas Cooperate with Kin to Colonize Hosts and Deter Rivals

“…; for a detailed phylogeny of the Entamoeba genus see Elsheikha et al. ). Some, like E. invadens IP‐1 and E. invadens VK‐1:NS, differ only in a single nucleotide in the ssrRNA sequence (Espinosa and Paz‐y‐Miño‐C , ,b), yet they discriminate one another as much as any other pair of phylogenetically more distant taxa (we infer that Ei ‐IP‐1 and Ei ‐VK‐1:NS differ substantially in their nuclear genomes, as distinctive species, but only the Ei ‐IP‐1 genome has been sequenced; Ehrenkaufer et al.…”

“…The seven clones depicted are representative of major lineages within the genus Entamoeba (for a detailed phylogenetic reconstruction of the genus see Elsheikha et al. ). Arrows indicate pairwise clone recognition experiments, as conducted in our laboratory, between: most closely related sister taxa E. invadens IP‐1 vs. E. invadens VK‐1:NS (marked as a); more distantly related sister taxa E. histolytica HM‐1:IMSS vs. E. dispar (marked as b); between a representative of a known multispecies clade (e.g., E. moshkovskii Laredo) vs. the most distant member of that clade ( E. terrapinae ; marked as c); and between members of two distinct clades ( E. histolytica HM‐1:IMSS vs. E. invadens VK‐1:NS, marked as d; or E. dispar vs. E. invadens VK‐1:NS, marked as e).…”