Molecular Characterization and Phylogenetic Analysis of Cryptosporidium spp. in Pediatric Acute Gastroenteritis: Epidemiological Insights from Northeastern Iran

Cryptosporidium spp. are significant zoonotic pathogens causing gastroenteritis, particularly in pediatric populations. This study aimed to investigate the prevalence, molecular characterization, and phylogenetic analysis of Cryptosporidium species among children with acute gastroenteritis in northeastern Iran. A cross-sectional study was conducted on 138 children aged 3 months to 12 years at Dr. Sheikh Hospital, Mashhad, between January 2023 and June 2024. Stool samples were examined microscopically using Ziehl-Neelsen staining, and molecular analysis was performed targeting the 18S rRNA gene through PCR. Positive samples were sequenced, and phylogenetic trees were constructed to assess genetic diversity. Microscopic examination detected Cryptosporidium oocysts in 23.2 % of samples, while molecular analysis identified Cryptosporidium DNA in 26.8 %, demonstrating the superior sensitivity of PCR. Sequencing results revealed Cryptosporidium parvum as the predominant species (14/15 samples) with one Cryptosporidium hominis case. Phylogenetic analysis confirmed genetic diversity among isolates, highlighting potential zoonotic and environmental transmission routes. No significant associations were observed between infection prevalence and demographic factors such as age or gender (p > 0.05). This study underscores the importance of molecular diagnostics in accurately identifying Cryptosporidium species and understanding their epidemiological significance. The findings contribute to regional knowledge on Cryptosporidium infections and highlight the need for targeted public health interventions to reduce disease burden in children.