Mansour Dabirzadeh , Reza Shahraki , Mohammadreza Beheshtizadeh , Mahdi Khoshsima Shahraki,
Volume 20, Issue 2 (6-2026)
Abstract
Background: Cryptosporidium is one of the most important protozoan parasites causing waterborne diseases worldwide. The parasite’s oocysts are resistant to conventional water treatment, making molecular detection crucial for identifying contamination sources.
Methods: A total of water samples were collected from different sites in Zabol and Zahedan, southeastern Iran. Microscopic screening was performed after concentration and staining with modified Ziehl-Neelsen and Trichrome methods under 1000× oil-immersion magnification. DNA was extracted from positive samples, and the SSU rRNA gene (~800-900 bp) was amplified by PCR. The resulting products were subjected to enzymatic digestion using AluI and RsaI restriction enzymes, and representative amplicons were sequenced.
Results: Microscopic examination confirmed the presence of Cryptosporidium oocysts in several water samples. PCR amplification successfully produced fragments of the expected size without nonspecific bands. AluI digestion revealed distinct fragment patterns consistent with Cryptosporidium spp., while RsaI showed no cutting sites. Sequence analysis through BLAST showed high identity (≥99%) with C. parvum isolates. The phylogenetic tree constructed using the BLAST distance-tree method grouped the sequence closely with C. parvum, confirming its identity.
Conclusion: Molecular characterization of Cryptosporidium from water samples in southeastern Iran indicated contamination primarily with C. parvum. These findings emphasize the necessity of continuous molecular surveillance to ensure the safety of drinking and recreational waters in the region.
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