Molecular detection of genetic types of <i>Cryptosporidium parvum</i> parasite causing diarrhoea in Mosul city

Cryptosporidium is a crucial zoonotic parasite that leads to self-limiting gastroenteritis. The primary species responsible for cryptosporidiosis are Cryptosporidium hominis and C. parvum. The objective of the study was the microscopic identification using the Modified Zeihl Neelsen and floatation using the sugar sheather solution, as well as using the molecular identification technology via the Nested Polymerase Chain Reaction (nPCR) to detect the 18SrRNA gene with DNA sequence analysis and the phylogenetic tree of some positive samples from various areas of Mosul city. Stool samples from 154 children under five with diarrhoea were collected at Ibn AlAtheer Teaching Hospital in Nineveh Governorate from July to December 2023. Samples were tested for Cryptosporidium using Modified Zeihl Neelsen stain and floatation techniques. DNA extraction and nPCR were performed for molecular analysis. The study showed that the infection percentage was 20.77% for 32 samples out of the total number of samples 154 stool samples, which were tested and microscopically identified in addition to the results of the molecular test that was conducted by using the Nested Polymerase Chain Reaction (nPCR) (32 samples were positive and 122 samples were negative) to confirm the accuracy of the microscope examination. The percentage of infection with C. parvum parasite was observed to be 18.75%, and the DNA sequencing of the infected samples was conducted. The three new isolates emerged for the first time in the Nineveh governorate and were registered at the National Center for the Biological Information (NCBI) with serial numbers (PP669700, PP669699, and PP669701).