الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Cyclospora is an obligate intracellular parasite belonging to protozoa in the phylum Apicomplexa, with an enteroepithelial cycle in man. This life cycle is divided in two stages exogenous and endogenous. In the exogenous stage, maturation of oocysts takes place outside the human body. While the endogenous stage occurs inside the human body, and involves both asexual and sexual stages. It is transmitted by contaminated water and food or by contact with contaminated soil.
Cyclospora cayetanensis (C. cayetanensis) infection in an immunocompetent host is not a major problem. While in immunocompromised people, it leads to persistant diarrhea. This may be fatal due to secondary critical dehydration. Extraintestinal complications as acalculous cholecystitis, thickened gall bladder and elevated alkaline phosphatase have been reported. Guillain-Barré and Reiter syndromes have been recorded in other cases.
The drug of choice for treating cyclosporiasis is co-trimoxazole, a combination of two antibiotics, trimethoprim (TMP) and sulphamethoxazole (SMZ). However, this combination is associated with many side effects such as gastrointestinal, haematologic, renal and allergic side effects. Moreover, many side effects were reported in pregnant females using co-trimoxazole. Relief of symptoms has been seen within one to three days after treatment. However, recurrence of symptoms occurs within one to three months in over 50 % of the patients. Therefore, there is an urgent need to develop an alternative anti- cyclospora drug that is efficient and non-toxic to human.
In the last decades, much attention has been paid towards the use of nanoparticles as an alternative to conventional antimicrobial agents due to their distinct advantages. The antimicrobial actions of nanoparticles (NPs) include cidal destruction of cell membranes, modifications of microbial cell wall and blockage of enzyme and nucleic acid pathways. Among these particles, the metallic NPs are the most promising due to their broad spectrum antimicrobial activity, durability, high resistance, selectivity and specificity. Silver nanoparticles (Ag NPs) have been the widely studied metallic NPs, and various theories explained their exact mechanisms of action. They have the ability to anchor to the cell wall, penetrating it and causing structural changes in the cell membrane. Furthermore, Ag NPs lead to the formation of free radicals which damage the cell membrane and make it porous. These free radicals cause break in DNA strands and kill the infectious agent. Moreover, Ag NPs are potent enhancers to the immune system, they recruit leukocytes and increase the cytokine levels.
Accordingly, this work was designed to e