Related Experiment Video
Updated: Jan 17, 2026
Detection and Genogrouping of Noroviruses from Children's Stools By Taqman One-step RT-PCR
Published on: July 22, 2012
Molecular Identification and Genotyping of Blastocystis Spp. In Children with Clinical Symptoms in Southeast Iran
H Mirahmadi1,2, M Rahmati-Balaghaleh1,2, E Darabi3
1Infectious Disease and Tropical Medicine Research Center, Research Institute of Cellular and Molecular Sciences in Infectious Diseases, Zahedan University of Medical Sciences, Zahedan, Iran.
Abstract:
Blastocystis spp. is a zoonotic anaerobic parasite that has been identified in the large intestine of humans and many vertebrates. It is predominantly encountered in individuals with frequent contact with animals. The present study aims to identify the prevalence of Blastocystis spp. and its common genotypes in children with clinical symptoms of diarrhea in the city of Zahedan, located in the southeast of Iran. A cross-sectional descriptive study was conducted on 60 children under ten years of age with gastrointestinal symptoms, especially diarrhea. Following the collection of samples, stool samples were subjected to direct stool testing for the initial diagnosis. Following this, a microscopic diagnosis was made, after which DNA was extracted and a Polymerase Chain Reaction (PCR) test with a small subunit ribosomal RNA (SSU rRNA) gene target was performed. The PCR products were then purified and sequenced. The resulting nucleotide sequences were then subjected to a thorough review using Chromas biotechnology software version 2.4 and CLC genomic work bench software 11. The alignment of the nucleotide sequences was subsequently facilitated by utilizing the BLAST database, and these sequences were then compared with the reference genotypes of Blastocystis spp. that are stored within the gene bank. The genotyping of the sequences was conducted using CLC genomic work bench software 11, and a phylogenetic tree was constructed using MEGA7 software with the Neighbor-Joining statistical method, which applied the Kimura 2-parameter method. Out of the 60 cases that were examined, 5 children (8.33%) were found to be positive by direct microscopic and PCR tests, where a 500 (479) bp fragment in the SSU-rRNA target was detected. Subsequent genetic analysis identified four distinct subtypes, including subtypes 1, 2, 3, and 5. The percentage of nucleotide identity with the sequences in the gene bank was found to be between 93 and 100%. Given the presence of subtypes 3 and 5 in the study and the evidence of their zoonotic nature, it can be concluded that examining parasite dynamics and epidemiological principles can be effective in the control strategy.
Insights
Blastocystis spp. parasites were found in 8.33% of children with diarrhea in Zahedan, Iran. Four subtypes (1, 2, 3, and 5) were identified, highlighting the zoonotic potential of Blastocystis infections.
Area of Science:
- Medical Parasitology
- Molecular Epidemiology
- Infectious Diseases
Background:
- Blastocystis spp. is a common zoonotic parasite found in the human and animal gut.
- It is frequently observed in individuals with close animal contact.
- Understanding its prevalence and genotypes is crucial for public health, especially in regions like Southeast Iran.
Purpose of the Study:
- To determine the prevalence of Blastocystis spp. in children experiencing diarrhea in Zahedan, Iran.
- To identify the specific genotypes of Blastocystis spp. circulating in this pediatric population.
- To provide insights into the potential zoonotic transmission routes.
Main Methods:
- A cross-sectional study involving 60 children under ten with gastrointestinal symptoms.
- Diagnosis using direct stool microscopy and Polymerase Chain Reaction (PCR) targeting the small subunit ribosomal RNA (SSU rRNA) gene.
- Sequencing of PCR products, followed by bioinformatic analysis (BLAST, CLC genomics, MEGA7) for genotyping and phylogenetic analysis.
Main Results:
- Blastocystis spp. was detected in 5 out of 60 children (8.33%) via microscopy and PCR.
- PCR identified a 479 bp fragment in the SSU-rRNA gene.
- Four subtypes (ST1, ST2, ST3, and ST5) were identified, with high nucleotide identity (93-100%) to reference sequences.
Conclusions:
- Blastocystis spp. is present in children with diarrhea in Zahedan, Iran.
- The identification of zoonotic subtypes (ST3 and ST5) suggests potential transmission from animals.
- Epidemiological surveillance and understanding parasite dynamics are key for controlling Blastocystis infections.
