الفهرس 
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Abstract
Parasitic infections in rodents are interesting area of study due to their role as intermediate hosts and reservoirs of several zoonotic helminthic and protozoan diseases.
The current study surveyed the intestinal parasites in 37 adult rats Psammomys obesus which captured from saline marsh areas of North Coast after Alexandria, Egypt. Fat sand rat (Psammomys obesus) species of muroid rodents (Rodentia: Muridae) represent common hosts for various parasites. The current study investigated intestinal protozoa and helminth infestation of Psammomys obesus. Morphologically, we identified four different types of parasites that infect Psammomyes obesus.
To our knowledge according to previous studies, the present study gives the first record to discover intestinal protozoa (Eimeria sp., & Sarcocystis sp) & helminthic infection by (cestoda, Raillietina trapezoides) and mixed infection by (nematode (Trichuris sp.) and cestoda (Raillietina trapezoids)) of trapped rodents which also is the first region for these host-parasite systems.
The results showed that the variation in helminth species was wide. We found sand rats infected by one genus of nematode, one genus of cestode and with mixed infection. Rats also were investigated for intestinal protozoa. Thirty-three rats were infected with the following: Trichuris sp.., 16 (48.48, %); Raillietina sp.., 4 (12.12, %); mixed infection of Trichuris sp. and Raillietina, 5 (15.15%) and protozoan parasites, 8 (21.6%); Sarcocystis sp. (one rat, 2.7%) and Eimeria sp. (7 rats 19.9%).
Two types of anemia were confirmed by hematological analysis; normocytic normochromic anemia and microcytic hypochromic anemia.
Studies on gastrointestinal infections have primarily focused on defining the pathological observation in infected host. Gross examination of both the small and large intestines revealed intestinal blockage (large worms) and diarrhea. The histopathological changes of the intestine showed degeneration of the intestinal mucosa; and atrophy of the villi and intestinal glands. Moreover, different parts of worms observed in the lumen of colon mucosa and at the tip of villi results in discontinuity of the muscularis mucosa and necrotic lesions on the mucosa, Examined rats infected with nematode and cestoda had necrotic colitis and enteritis. The presence of two types of anemia was confirmed by hematological analysis. In addition, two types of eggs were noted: eggs of Trichuris sp. (16 rats) and eggs of Raillietina sp. (4rats).
Also, Examination of histological sections of small intestine revealed some developmental stages of Eimeria sp. Include schizont, male and female gametocytes in the lumen, mucosa and lamina propria of intestine. Degeneration, destruction, sloughing, denudation and hyperplasia of epithelium of intestinal villi were also noticed. In addition hyperplasia of Peyer’s patches with lymphocytic infiltration were observed. Sarcocysist sp. was found in muscularis and intestinal submucosa with the resultant of destruction of the villi and crypt atrophy of the adjacent cells and discontinuity of the muscularis mucosa due to cyst formation.
Further studies should be conducted in other parts of Egypt to discuss the most significant factors predicting the route of infections, the prevalence and intensity of infection of the parasites, their relation to the habitat of the host and how this species of rodents take these different infection.
from this study we can conclude that:
The parasites infecting Psammomys obesus were morphologically identified with their pathological effects. The most prevalent helminth was found to be the nematode, Trichuris muris, 16 (48.48%); followed by the cestode, Raillietina trapezoides, 4 (12.12%) and finally mixed infection of Trichuris muris and Raillietina trapezoides, 5 (15.15%) and protozoan parasites, 8 (21.6%); Sarcocystis sp. (one rat, 2.7%) and Eimeria sp. (7 rats 19.9%).
Higher prevalence and intensity of infection were observed in Trichuris muris infection. Raillietina spp are zoonotic and may cause patent intestinal infections in humans worldwide. Intestinal parasitic infections still remain important public health problems in developing countries including Egypt. So further studies should be conducted for assess the relevance of rats carrying zoonotic parasites for public health in Egypt.