Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 14 4 2019 12 29 614 622 EN Doaa A. AHMED Department of Parasitology, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt Mona A. RABBO Department of Parasitology, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt Manal JAMJOOM Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdul Aziz University, Riyadh, Saudi Arabia Hala S.SALEM Department of Parasitology, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt Marwa A. GHIETH Department of Medical Parasitology, Faculty of Medicine, Beni Suef University, Beni-Suef, Egypt 2018 02 15 2018 11 21 Background: Giardiasis is one of the commonest intestinal parasitic diseases that affects wide range of age groups. We aimed to detect the pattern of Giardia intestinalis assemblages among symptomatic patients at the age of 2 up to 40 years. Methods: Stool samples were collected from 278 patients and examined microscopically and genetically for giardiasis. Giardia was diagnosed using wet mount examination and subjected to molecular assays targeting three genes, glutamate dehydrogenase (gdh) using semi-nested PCR (nPCR), β-giardin (bg) and triose phosphate isomerase (tpi) using nPCR. Amplified products were subjected to genotyping using PCR-restriction fragment length polymorphism (PCR-RFLP) targeting gdh and bg genes. Results: Among 48 samples positive by microscopy and by a minimum of one of the three used genes, genotyping was successful among 23 samples (47.9%). Assemblage B was more prevalent (16/23, 69.6%), than assemblage A (4/23, 17.4%) and 3 (13%) isolates were identified as assemblage B at gdh locus which later were identified as assemblage A at bg locus. Sub-assemblage AII (3/4, 75%) and sub-assemblage BIII (12/15, 66.7%) were predominate at gdh locus. Age groups was an estimated risk factor for infection with assemblage B with a peak (87.5%) during 6 to 12 years (P<0.05), diarrhea and abdominal pain (OR (95%CI) = .654 (.094, .963); .201 (.048, 1.009), respectively) were significantly associated with assemblage B. Conclusion: It is recommended to suspect infection with giardiasis assemblage B by physicians during late childhood presenting with diarrhea and abdominal pain https://ijpa.tums.ac.ir/index.php/ijpa/article/view/1999