الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Soil is the top layer of crust which covers the surface of the earth and it is considered one of the most important non-renewable environmental resources. It is divided into three main types accordin g to the size of soil particles; clay, sandy and loamy soil. Soil is made up of inorganic and organic components which allow growth
of plants, bacteria and parasites. The latter can be transmitted to man causing different Parasitic diseases. Soil transmitted parasitic diseases (STPD) tend to go unnoticed, and
hence under recorded, not only because the symptoms are often quite general, but also because they may be mistaken with a wide range of other infectious diseases.
Soil plays different roles in transmission of various parasites. It acts as a good medium for maturation and development of many parasitic stages. It acts also as a vehicle facilitating the invasion of the parasites to new hosts and lastly it serves as a reservoir in which the infective stages can remain viable for a long period.
Soil transmitted parasites (STPs) include soil- transmitted helminths (STHs) or geohelminths, soil-transmitted protozoa (STP) and also, some larval stages of higher diptera. STHs may belong to intestinal nematode Ascaris lumbricoides (A.lumbricoides), Trichuris trichiura (T. trichiura), hookworm spp. either human or non
human, Strongyloides stercoralis (S. stercoralis) and Toxocara spp. in which man is a paratenic host. Cestodes as Taenia solium (T. solium), Hymenolepis nana (H. nana) and Echinococcus granulosus ( E. granulosus) belong also to STHs. Soil is also an important and a main source of infection with a wide range of diseases either intestinal or tissue as Isospora belli (I. belli), Cyclospora cayetanensi(C.cayetanensis). Cryptosporidium parvum (C. parvum), Microsporidia spp. and Toxoplasma gondii (T. gondii). Alexandria is considered to be one of the most important coastal cities of Egypt. It is provided with nearly all soil types including; clay, sandy and loamy. All these soil types, can act as sources of parasitic infections to the local inhabitants and to the regularly migranting population.
The aim of the current study was to recover different stages of parasites, which have medical importance, from soil samples collected from different districts of Alexandria. It also aimed at determination the intensity of soil contamination and viability of the detected parasites in relation to the seasonal variation and the type of soil.
To fulfill the aim, 210 soil samples of different types (sandy, clay and loamy)
were collected from different districts of Alexandria governorate along the period of one year (September 2008- August 2009). Thirty soil samples were collected from each district. First the type of soil in each sample was determined, and then any obvious soil contamination with larvae of higher diptera or segments of cestodes was
recorded. Hoyer’s media was used in clearing and mounting of the detected larvae of higher diptera while the segments of cestodes were stained with carmine stain for further identification. Then each soil sample was examined using sedimentation and
flotation concentration techniques to detect various parastic stages including; eggs, larvae, cysts, oocysts and spores. Modified Baermann’s technique was also used to isolate nematode larvae from soil samples. In addition, centrifugation technique of soil samples that come in contact with collected stagnant water was performed to detect the presence of free living pathogenic amoebae.