الفهرس 
ACKNOWLEDGEMENTS
Phylum MicrosporidiaOnly 14 pages are availabe for public view
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Abstract
Parasitism is one of the major problems which inflict heavy economic losses to poultry. In Egypt, Poultry production is formed of two main sectors; house hold sector and commercial sector. The present study was designed to: determine the prevalence and the seasonal dynamic of protozoan infection of HRC and FRC, identify their intestinal and blood protozoa by using different technique and to identify the histopathological changes induced by intestinal and tissue protozoa. Two hundred samples were collected from apparently healthy domestic chicken from July 2016 to July 2017. Intestinal protozoa showed higher prevalence in HRC (70%) than FRC (36%). The low hygienic measures of HRC lead to unhealthy growth and birds become more prone to infection. Eimeria sp. had an overall prevalence of 22%. This high prevalence may be warning sign of the endemicity of Eimeria sp. and need to be ascertained in a large scale studies. Eimeria sp. reported high significant difference between the prevalence of HRC 32% and the FRC 12%. The warmth and moisture environment favors greater transmission and contamination of oocysts in the uncontrolled environment of HRC. Therefore Eimeria sp. highest prevalence was in autumn and the least occurred in summer. The seasonal pattern of the disease mostly correlated with the ambient temperature and relative humidity; optimum oocyst sporulation and survivability occurs at temperature (21-30 °C) and humidity (45-80%).Seven Eimeria sp. were identified in the current study. Identification of Eimeria sp. was done using the oocysts and sporocyst morphometry and histopathology.By histopathology Eimeria tenella was identified by its unique character in which secondary stage schizonts are present in the form of clusters or colonies in the cecal epithelium. E. tenella was the most pathogenic species that causes severe necrosis of epithelial cells. Eimeria necatrix showed its typical chronic lesion; severe necrosis of epithelial cells, hyperplasia of crypts of Lieberkuhn and thickening of the intestinal wall. Eimeria maxima was found in jejunal sections, different developmental stages were found just beneath the basement membrane and were of large size. Eimeria praecox was found in duodenal sections, schizonts are found in epithelial cells of the sides of intestinal villi.The histopathological changes observed for each species were quite similar to what was previously described in other studies.In the present study, Cryptosporidium sp. infection was more pervasive in HRC (24%) than in FRC (14%).This relatively higher presence in FRC might be due to: Younger broiler chickens are more susceptible to infection with Cryptosporidium sp., Cryptosporidium oocysts are resistant to the commonly used disinfectants. Water introduced to the flocks is not treated before consumption as water is known to be one of transmission routes.Seasonal distribution of Cryptosporidium sp. was found that the relatively high prevalence of infection was recorded in autumn (28.5%) and lower in summer (11.7%). Increasing temperature adversely affect its viability and infectivity. High humidity and low temperature harmfully affect the bird health condition. The role of our study to high light the prevalence of Cryptosporidium sp. in both HRC and FRC. That may through the light to the presence of human infection in parallel with the peak of its presence in chicken. Blastocystis sp. has significantly higher prevalence in HRC than FRC (37% compared to 24%) respectively. Good hygiene is possible inhibitor of environmental contamination and thus the feco-oral transmission of the parasite. Blastocystis sp. prevalence rate increased with the increase of environmental temperature with statistically strong positive correlation (Pearson correlation coefficient = 0.88). Summer season had the highest prevalence and heaviest intensity of Blastocystis sp. infection.Tetratrichomonas gallinarum was encountered only in ceacal contents of HRC with prevalence of 16%. Highest prevalence was in autumn (29.16%), while it was not detected in summer season. Trichomonads require moist conditions for environmental persistence. Commensal parasites were encountered; C. gallinarium, C.anatis, E. gallinarum and E. gregariniformis in HRC, while in FRC they were not present. This is may be attributed to the low hygienic measures, ease of access of wild birds and raising of several poultry species in the same house. Cochlosoma anatis is reported for the first time as natural infection in chicken in Assiut. It was found in the ceacal contents of one of HRC (1%). The infected chicken might be raised with the natural host (ducks) in the same house. Microsporidium sp. was detected in 6% of the examined HRC samples and 4% of FRC.In the present study, direct fecal examination was done by examination of unstained, iodine stained and lacto- phenol cotton blue stained wet mounts. Concentration technique, Formel ether sedimentation was used.Blood protozoa were not detected in FRC blood samples, while in 8% of HRC blood samples. Plasmodium gallinaceum was encountered in (3%), Agyptinella pullorum, Ehirlichia sp. (2%) and Atoxoplasma sp. (1%).For the first time, Ehrlichia sp. is reported in the current study in domesticated bird; HRC. It was reported previously in wild birds; in Flamingo in Giza, Egypt and in Saker falcons in Kuwait.Out of the examined Giemsa stained 200 brain impression smears only two were suspected to be infected with T. gondii (one house and one farm samples). The low reliability of the tissue impression smears results come from the limited sample size, random distribution of tissue cysts, and perhaps low numbers of T. gondii tissue cysts in the tested chicken tissues. Cryptosporidium sp. was encountered in 5 out of 30 examined bursa of fabracius impression smears. One out of 18 kidney examined impression smear of egg laying house raised hens was positive.