Molecular Diagnosis and Phylogenetic Investigation of Entamoeba histolytica and Giardia intestinalis among Diarrheal Patients in Iraq

 Entamoeba histolytica and Giardia intestinalis are two common parasites associated with gastrointestinal infections and diarrheal diseases worldwide. This study investigated the prevalence, molecular characterization, and phylogenetic relationships of E. histolytica and G. intestinalis among patients with diarrhea and intestinal disorders in hospitals across Iraq.

 Stool samples were collected from individuals presenting with gastrointestinal symptoms, and a microscopic examination was performed to screen for the presence of E. histolytica and G. intestinalis. DNA was extracted from positive samples, and PCR amplification targeting the 16S rRNA gene for E. histolytica and the triose phosphate isomerase (TPI) gene for G. intestinalis was carried out. The resulting PCR products were subjected to agarose gel electrophoresis, purified, and sequenced. Phylogenetic trees were constructed using the Maximum Likelihood method based on the Tamura-Nei model, and bootstrap analysis was performed.

Among the studied samples, 27.8% (n=85) were positive for E. histolytica, while 19.6% (n=60) were positive for G. intestinalis. Sequence analysis confirmed the presence of E. histolytica and G. intestinalis by matching the obtained sequences with those available in the NCBI gene bank. The phylogenetic analysis revealed the genetic diversity and relatedness of the E. histolytica and G. intestinalis isolates. Clustering patterns specific to the Iraqi population were observed, suggesting potential regional transmission dynamics.

 This study provides valuable insights into the prevalence, molecular characterization, and phylogenetic relationships of E. histolytica and G. intestinalis in Iraqi patients with diarrhea and intestinal disorders.