Cryptosporidium Detection in Pediatric Diarrheal Cases: Microscopic, Immunological and Molecular Approaches in Kirkuk, Iraq

Abstract

Background: Cryptosporidium is a protozoan parasite that causes digestive issues in children and is a major contributor to the increasing burden of waterborne parasitic infections. It is recognized as one of the primary causes of diarrheal disease among children. In low-resource settings like Iraq, poor sanitation significantly elevates the risk of outbreaks, thereby threatening child health and adding to the economic burden. Objective: This study aimed to assess and compare the diagnostic performance of four distinct techniques: direct smear microscopy stained with modified Ziehl-Neelsen (MZN), concentration (formalin-ether sedimentation), rapid immune-chromatography, and molecular-PCR techniques for the detection of Cryptosporidium among diarrhoeic children in Kirkuk City, Iraq. Methods: A total of 150 stool samples were collected from diarrhoeic children across multiple hospitals between September 2024 and March 2025. These samples were analyzed using four diagnostic approaches. Results: Out of 150 samples, 91 (60.7%) tested positive using MZN, 96 (64%) via concentration, 103 (68.7%) through rapid immune-chromatography, and 111 (74.0%) using PCR. Compared to PCR, the sensitivity for MZN, concentration, and rapid immune-chromatography was 62.16%, 63.96%, and 74.86%, respectively; specificity was 43.59%, 35.89%, and 48.72%, respectively. Statistical analysis revealed no significant agreement for MZN and concentration (p = 0.527, 0.988), while rapid immunochromatography showed significant concordance (p = 0.007). Conclusion: While MZN, concentration, and rapid tests are useful, PCR remains the most sensitive and specific, offering genotyping capability, batch processing suitability, and high diagnostic accuracy, PCR is considered a valuable tool for future diagnostic and molecular epidemiological studies.