Identifying zoonotic risks: molecular insights into Cryptosporidium and Enterocytozoon bieneusi in pediatric cancer patients in Ahvaz, 2024.

Opportunistic infections remain a major cause of morbidity and mortality among patients with immunodeficiency and malignancy. Cryptosporidium spp. and microsporidia, particularly Enterocytozoon bieneusi, are obligate intracellular parasites that can lead to severe complications and even death in immunocompromised individuals.In this cross-sectional study, 60 stool samples were collected from pediatric oncology patients aged 5-18 years who were hospitalized at Baghaei 2 Hospital in Ahvaz, southwestern Iran, in 2024. Following DNA extraction, molecular analysis was performed to detect the presence of Cryptosporidium spp. and E. bieneusi. For genotyping, amplification and sequencing of the 60-kDa glycoprotein (gp60) gene for Cryptosporidium spp. and the internal transcribed spacer (ITS) region for E. bieneusi were conducted. A total of 16 samples (26.6%) tested positive for either C. hominis or E. bieneusi. Co-infection with both pathogens was identified in two patients (3%). Statistical analysis revealed no significant association between gender and parasitic infection (P = 0.166), nor between the type of malignancy and presence of protozoa (P = 0.717). Genotyping of E. bieneusi showed the presence of BEB6, CHG3, D, and I genotypes, with BEB6 being the most prevalent. Subtyping of C. hominis revealed the presence of the IeA11G3T3 subtype. Overall, the molecular findings demonstrated a prevalence rate 26.6 % of parasitic infection among the studied population, with E. bieneusi being predominant. The detection of potentially zoonotic genotypes, particularly BEB6, underscores the likelihood of zoonotic transmission routes in these patients.