The morphology, life cycle, host specificity, incidence of Cryptosporidium baileyi and C. meleagridis, and the epidemiology, Clinical signs, pathology, immunity diagnosis, therapy, and control of cryptosporidiosis in birds are reviewed.

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The very low sedimentation speed of Cryptosporidium parvum, C. muris, and C. baileyi oocysts is reported. The regression of the sedimentation speed of oocysts in fecal suspension and tap water could be described by exponential equations. Depending on temperature, sedimentation media, and species, between 0.5 – 3.5 days were needed for the total disappearance of oocysts from the upper layer of water. This characteristic might be attributed to directive selection of cryptosporidium spp. For low density through the way of transmission. The settlement of C. Parvum was slower than that of C. baileyi or C. muris. The slow disappearance of Cryptosporidium oocysts from sewage, surface waters, and public water supplies could be one of the major factors responsible for the transmission of this parasites via drinking water.

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Cyst merozoites of the protozoan parasite Sarcocystis muris (Apicomplexa) contain three major microneme proteins at least with apparent molecular masses in the range of 15kDa. The polypeptides are lectins with affinity to galactose and some of its derivatives. At up to a concentration of 10 µg/ml of the lectin fraction no stimulation of [³H]-thymidine incorporation was detected for spleen cell populations isolated from uninfected mice, which serve as natural intermediate host of Sarcocystis muris. However, the lectin fraction reduced stimulation of splenocytes that were responsive to Concanavalin A. Two of the proteins mentioned above had been cloned and sequenced. The deduced molecular masses are 15.1 kDa and 15 kDa, respectively. We report here on the expression, purification, and functional analysis of the 15.1 kDa microneme protein. The polypeptide was expressed in a non-native state in Escherichia coli inclusion bodies as a fusion protein with a poly(His) leader. The fusion protein could be purified by metal affinity chromatography and renatured in vitro. After refolding, the leader peptide was removed by proteolysis with enterokinase. Final purification of biologically active recombinant lectin molecules was achieved by lactose affinity chromatography. The identity of the recombinant protein could be confirmed by western blot analysis with a monoclonal antibody, known to be directed against one of the major microneme antigens at least. With regard to the influences on murine splenocytes, the recombinant protein seems to have the same effects like the native lectin fraction.

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Invasion specificity of Eimeria stiedai sporozoites to cultured rabbit liver biliary cells, parenchymal hepatocytes and kidney cells was monitored. lntracellular　sporozoites　were　observed　in　liver　biliary　epithelial　cells, as early as 3 hrs when an infection rate of 5% was recorded. Infection rate for rabbit liver biliary epithelial cells was monitored for 6 hrs and increased to approximately 9％ at this time. No intracellular parasites were found in rabbit parenchymal hepatocytes and rabbit kidney cells, even on prolonged culturing. In the liver biliary epithelial cells inoculated with fixed sporozoites, no intracellular parasites were found. Sporozoites attached on the cell surface of the liver biliary epithelial cells fixed with paraformaldehyde, but did not penetrate. Serum of mice immunized with rabbit liver biliary epithelial cells, showed antibody reactivity to liver biliary epithelial cells, higher than, that of rabbit parenchymal hepatocytes and rabbit kidney cells. After absorption with parenchymal hepatocytes, antibody reactivity to liver biliary epithelial cells in the serum still retained. Sporozoite penetration activity in the liver biliary epithelial cells reduced by the supplement of the serum of mice immunized with rabbit liver biliary epithelial cells in the culture medium. These results suggest that Eimeria stiedai sporozoites penetrate the hepatobiliary cells selectively and these epithelial cells have the sporozoite binding site(s) which might be identified by specific antibody.

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A set of primers were designed according to the published sequence of the gene encoding a rhoptry protein of Babesia caballi, and used to amplify parasite DNA from the blood samples obtained from carrier horses by polymerase chain reaction (PCR) method. The PCR method was sensitive enough to detect parasite DNA from 2.5μｌ blood sample with a　parasitemia　of　0.000001%. The PCR method was compared with fIuorescent antibody test (IFAT) in order to evaluate the diagnosis efficiency for B. caballi infection in horses. Of 142 field samples from Mongolia, 28 (20%) and 96 (69％) samples were identified positively by PCR and IFAT, respectively. Although the sensitivity of PCR was lower than IFAT, it was noted that the 5 IFAT-negative samples were PCR-positive, suggesting that the combination of PCR method and IFAT for diagnosis of B. caballi infection may be effective in detecting the carrier horses.

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