Gene migration for re-emerging amebiasis in Iran's northwest-Iraq borders: a microevolutionary scale for reflecting epidemiological drift of Entamoeba histolytica metapopulations

Abstract

In the microevolutionary scales of Entamoeba isolates, the gene migration shows how Entamoeba spp. has epidemiologically drifted among border countries. Five hundred fecal samples were taken from patients suffering gastrointestinal disorders, abdominal pain, and diarrhea at Saggez, northwest Iran located within the border Iraq country. Following parasitological techniques, DNA samples were extracted and amplified by polymerase chain reaction (PCR) of 18S rRNA region to identify Entamoeba infections. To distinguish the Entamoeba spp., a multiplex PCR was conducted. Amplicons were sequenced to reconfirm their heterogeneity traits and phylogenetic analysis. Additionally, Entamoeba histolytica sequences of Iraq were retrieved from GenBank database. The suspected isolates were diagnosed as E. histolytica (2.2 %), Entamoeba moshkovskii (1 %), and Entamoeba dispar (0.4 %). Mixed Entamoeba infections did not detect among isolates. A parsimonious network of the sequence haplotypes displayed star-like features in the overall isolates containing E.h1, E.d2, and E.m3 as the most common haplotypes. According to analysis of molecular variance (AMOVA) test, high partial value of haplotype diversity (0.700 to 0.800) of E. histolytica was shown the total genetic variability within populations while nucleotide diversity was low among Iranian and Iraqi metapopulations. Neutrality indices of the 18S rRNA were shown negative values in E. histolytica populations which indicating significant deviations from neutrality. A pairwise fixation index (F-statistics [Fst]) as a degree of gene flow had a low value for all populations (0.001) while the number of migrants was 2.48. The statistically Fst value indicates that E. histolytica isolates are not genetically differentiated among shared isolates of Iran and Iraq. Occurrence of E.h1 between two regional populations indicates that there is dawn of Entamoeba flow due to transfer of alleles from one population to another population through host mobility and ecological alterations. To evaluate the hypothetical evolutionary scenario, further study is required to analyze Entamoeba spp. in the neighboring Middle East countries.

Keywords: Entamoeba spp.; Fst; Gene flow; Iraq; Northwest Iran.