الفهرس 
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Abstract
Cryptosporidium is an apicomplexan parasite that causes a wide¬spread infection in humans and animals. The parasite completes sexual and asexual reproduction in the intestinal epithe¬lial cells of a single host. The oocyst, the infectious stage of Cryptosporidium, is immediately infectious upon excretion with the host faeces. It is transmitted to humans by direct contact with animals, person to person transmission or through ingestion of contaminated water and food. Regularly, the infec¬tion is either asymptomatic or results in a self-limited diarrhea. Children, elderly people and immunocompromised individuals are at risk of more severe infections.
Diagnosis of cryptosporidiosis relies mainly on microscopic demonstration of oocysts in faecal samples using acid-fast staining methods. Several concentration techniques have been described to enhance oocysts recovery prior to staining. Alternatively, diagnosis can be made by the detection of Cryptosporidium coproantigen using the recently developed immunoassays.
The present study was conducted to compare and evaluate three diagnostic techniques for detectionof Cryptosporidium infection in fecal samples of preschool and school children.
The study was carried out on 50 preschool and 50 school children in Arab El-Mahder village, Khafr El-Sheikh Governorate. They were randomly selected from those attending the local rural health unit and primary school.
Stool samples of participating children were concentrated by FEA (10% formalin preserved samples) and Percoll (fresh samples) sedimentation techniques. FEA sediment was examined microscopically for parasitic cysts and ova. The sediments obtained from both techniques were stained by modified Ziehl Neelsen stain, and examined under oil immersion lens for Cryptosporidium oocysts.A portion of each faecal specimen was tested with an ELISA assay for detection of Cryptosporidium coproantigen.
The present study revealed that 48% of children had intestinal parasitic infections. (35% protozoal infection and 16% helminthic infection ).
The overall percentage of Cryptosporidium infection was 7%. FEA techniques detected the highest Cryptosporidium infection (5%), as compared to ELISA and Percoll (3% and 1% respectively). All cases diagnosed by microscopic examination were of low intensity.
A higher percentage of Cryptosporidium infection was observed among males as compared to females (9.25% versus 4.34 %). Regarding age, the percentage of infection was relatively higher among preschool age (8%) as compared to school children (6%). However, the difference was not statistically significant regarding both gender and age.
The agreement between ELISA and FEA was moderate. FEA failed to detect oocysts in one samples tested positive by ELISA while ELISA missed three positive cases detected by FEA.
Poor agreement was revealed between Percoll and both FEA and ELISA. No samples gave concordant positive results. Percoll sedimentation detected only one positive sample which was missed by FEA and ELISA.