• Parasites, Hosts and Diseases
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• v.33 no.1
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• pp.45-54
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• 1995

Two-day-old chickens{\;}and{\;}mallards were orally inoculated with one of % doses varying from $2{\;}{\times}{\;}10^2{\;}to{\;}2{\;}{\times}{\;}10^6$ of C. bailevi oocysts per individual. Generally, the more oocysts Inoculated were, the longer the patent periods were, and the more oocysts shedding were. Meanwhile increasing the inoculative dose, the prepatent periods were shortened except that mallards inoculated with $2{\;}{\times}{\;}10^2and{\;}2{\;}{\times}{\;}10^3$ oocysts foiled to produce the oocysts. The more parasites involving oocysts appeared from the chicken in comparison to the mallard. In the chickens challenged with a single dose of $2{\;}{\times}{\;}10^6$ oocysts, a small number of oocysts were detected from feces on days 4-14 after challenge infection (ACI) in all of carrageenan administered groups and in the control groups inoculated with $2{\;}{\times}{\;}10^2{\;}and{\;}2{\;}{\times}{\;}10^3$ oocysts. In the mallards, a few oocysts were also recognized on days 5-15 ACI in all of carrageenan treated groups and in the control groups inoculated with $2{\;}{\times}{\;}10^2,{\;}2{\;}{\times}{\;}10^3{\;}and{\;}2{\;}{\times}{\;}10^4$ oocysts. Just prior to challenge infection, phagocytic activity of peritoneal macrophages (Me) and the number of peripheral Mc in both birds were significantly decreased in the carrageenan treated groups as compared to the control groups. Mild challenge inection in both birds denoted that the immunogenicity of C. bailelli to the birds was very strong, despite MB blocker carrageenan administration.

• Parasites, Hosts and Diseases
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• v.35 no.3
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• pp.181-188
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• 1997

In order to clarify the effect of cryptosporidiosis on immune response, histopathological changes associated with experimentally occurring bursal cryptosporidiosis in chickens were chronologically observed as the first step. A total of 150 2-day-old chickens was each inoculated orally with a single dose of 5 × 105 Cryptospori,mum bailevi oocysts. The chickens showed a normal profile of oocyst shedding in droppings. The bursa indices throughout the experimental period indicated negligible reactions. Numerous cryptosporidia occurred in the microvillous border of bursal epithelium between days 4 and 16 postinoculation (PI). Appearance of the most mast cells was followed by a dramatic loss of the protozoa in the bursa of Fabricius (BF). The distribution of the coccidium coincided with heterophil infiltration in the epithelium and adjacent lamina propria. The histopathological lesion was marked diffuse chronic superficial purulent bursitis with heterophil infiltration in the epithelium and adjacent lamina proprla and mucosal epithelial hyperplasia. These results suggest that the bursitis may induce immunosuppressive effect.