Prevalence and Molecular Characterization of Cryptosporidium Species in Patients With Hematologic Malignancies in Eastern Iran

Introduction Cryptosporidium is a leading protozoan cause of diarrheal disease globally, posing a significant threat to immunocompromised individuals, including patients with hematologic malignancies. This study was aimed at finding out how common Cryptosporidium is, what species and genotypes are present, and what risk factors are linked to patients with leukemia and lymphoma in Birjand, South Khorasan. This region has not had this information available before. Methods In this cross‐sectional study conducted in 2023, stool samples were collected from 55 patients with confirmed hematologic cancers at Iranmehr Hospital, Birjand. Samples were examined using microscopy (modified Ziehl–Neelsen stain), and all were subsequently analyzed using a nested PCR assay targeting the gp60 gene for species and subtype identification. Demographic and risk factor data were collected and analyzed for association with infection using Fisher′s exact test. Results The overall prevalence of cryptosporidiosis was 3.6% (two out of 55 cases). One case was found in a patient with leukemia (one out of 34; 2.9%), and another in a patient with lymphoma (one out of 21; 4.8%). The difference in prevalence between these groups was not statistically significant. Molecular analysis identified all isolates as Cryptosporidium parvum . Sequencing revealed two zoonotic subtypes: IIaA in the lymphoma patient and IIdA in the leukemia patient. A statistically significant association was found between infection and contact with animals ( p = 0.004) and having a high‐risk occupation ( p = 0.03). Conclusion As the first report in our study area, we identified a 3.6% prevalence of cryptosporidiosis among patients with hematologic malignancies in Birjand, with zoonotic C. parvum subtypes as the sole etiological agents. The results emphasize the significant role of zoonotic transmission in this population and indicate a critical need for tailored preventive counseling to mitigate exposure risks associated with potential animal reservoirs for these vulnerable patients.