Comparative Research Study on Laboratory Diagnostic Techniques for Cryptosporidium parvum Parasites

Background: Cryptosporidiosis is a diarrheal disease caused by microscopic parasites of the genus Cryptosporidium. The outer shell of Cryptosporidium is protected by, allowing it to survive outside the body for long periods and making it very resistant to chlorine–based disinfectants. Both the disease and the parasite are commonly known as “Crypto". The symptoms of an infected individual depend on factors such as infective dose, host age, immune status, and nutritional status. Cryptosporidiosis is a common zoonotic disease, and transmission occurs through contaminated water or food. Methodology: Between November 2024 and January 2025, 80 stool samples were collected from individuals across different age groups who were infected with diarrhea in Najaf City. These samples underwent three diagnostic tests: general stool examination (GSE), Ziehl–Neelsen (ZN) stain, and rapid test. A complete blood count (CBC) was also conducted on samples that tested positive for Cryptosporidium to assess haematological changes, particularly in white blood cell subtypes. Results: Cryptosporidium infections were detected in 13.7% of the samples. Among the methods used in diagnosing this parasite, the Ziehl–Neelsen (ZN) stain technique proved to be the most effective diagnostic method, successfully identifying oocysts and various developmental stages of the parasite. The highest infection prevalence was observed in rural areas (19.5%), among individuals aged 11–21 years (27.7%), and in males (15.5%). The complete blood count (CBC). However, lymphocytes, particularly CD4+ T cells, were significantly elevated. Conclusion: The prevalence of infection in Najaf varies among different age groups, genders, and regional demographics. Ziehl–Neelsen (ZN) stain is the most reliable diagnostic method.