Yasuhide SAITO
Department of Parasitology, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara 229, Japan.

Abstract
Two groups of three quails were inoculated orally with 1.0 x 10^7 oocysts of Cryptosporium sp. isolated from chickens in Japan. One group of them was treated with dexamethasone phosphate before inoculation. Both groups shed oocysts from day 4 post-inoculation (PI). Their maximum OPG values (number of oocyst per gram of feces) were in the range of 105 and the patency was 7 to 9 days. In a separate experiment , young (one week old) and adult (7 weeks old) Japanese quails were inoculated orally with 3.0 x 10^6 oocysts. The OPG values of young quails were higher than that of adult ones, although the prepatent period and the patency were the same, suggesting that young quails are more susceptible to this parasite than older ones. When the younger quails were necropsied on days 6 and 7 PI, several asexual and sexual stages were found in the bursa of Fabricius and cecum. Japanese quails of both age groups were challenged with 3.0 x 10^6 oocysts on day 35 after primary challenge inoculation. Theses results demonstrate that this parasite has infectivity and immunogenicity to Japanese quails.

Key words: chicken Cryptosporium; infectivity; Japanese quail; immunogenicity; oocyst production.