الفهرس 
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Abstract
Background: Human cryptosporidiosis caused by Cryptosporidium parasite has been recognized worldwide as the most common cause of protozoal diarrhea leading to significant morbidity and mortality in industrialized nations and developing countries. The vast majority of human cases of cryptosporidiosis worldwide are caused by two species: Cryptosporidium hominis, which causes infection in humans only, and Cryptosporidium parvum which causes infections in humans and animals. Exposition of Cryptosporidium genotypes by molecular assays is required to recognize sources of infections and routes of transmission, facilitating the improvement of risk assessment and measures for prevention and control. The aim of the present study was to detect and correlate native Cryptosporidium molecular genetic variability among human isolates in Greater Cairo, Egypt, with their respective demographic, environmental and clinical manifestations.
Method: A total of 350 human stool samples collected from Egyptian patients from Greater Cairo, Egypt, with variable demographic, environmental and clinical presentations were subjected to modified Ziehl-Neelsen stain. Then, they were examined by RIDA QUICK Cryptosporidium/Giardia immunochromatography kit. All positive Cryptosporidium samples diagnosed by stain and/or kit were processed for Deoxyribonucleic acid (DNA) extraction. The extracted DNA samples were genotyped using nested polymerase chain reaction- Restriction fragment length polymorphism (nPCR-RFLP) targeting Small-subunit ribosomal Ribonucleic acid (SSU rRNA) and Cryptosporidium oocyst wall protein (COWP) genes.
Results: Screening by modified Ziehl-Neelsen stain detected Cryptosporidium in 5.7% (20/350) of patients. ICT kit could diagnose 9.4% (33/350). Only 15/40 samples were successfully amplified of the positive samples by microscopy and/or Crypto-Giardia immune-chromatography kit, using COWP gene. While all samples couldnot be amplified by SSU rRNA gene. All samples (15) were confirmed to be Cryptosporidium hominis by nested PCR-RFLP analysis of COWP gene. Significant associations were found between gender, drinking ground water, immunodefficient patients, fever, watery and mucoid stool and consumption of ready made salad and unwashed fresh vegetables and cryptosporidiosis.
Conclusion: Cryptosporidium hominis is the dominant genotype in the current study, indicating that transmission of cryptosporidiosis among patients is anthroponotic and not zoonotic.