In November, 1975, some adult sheep produced in Japan began to suffer from fever, anemia, palpitation, tachypnea, and hemoglobinuria. Light and electron microscopy revealed that many parasitic organism of Eperythrozoon ovis were present on the surface of erythrocytes. With an increase in parasitic rate, the erythrocyte count, hematocrit, and hemoglobin values decreased, erythrocytic resistance was reduced, and hemoglobin plasma appeared. When a splenectomized and an intact sheep were inoculated with blood from a spontaneously infected sheep, Ep. ovis began to appear in their peripheral blood 10 and 12 days after inoculation, respectively. The inoculated sheep manifested the same clinical signs and hematological changes as the spontaneously infected one. This report was the first to confirm the presence of Ep. ovis in Japan.
A trial was performed to clean a pasture contaminated with Dictyocaulus viviparus by suspending grazing for a given period in summer. Pasture renovation was also examined for effect on the control of infection. A month's suspension of grazing could not protect cattle from infection. Two months' suspension of grazing could protect cattle from infection in a pasture mildly contaminated previously. Infection was reduced only in intensity in a pasture severely contaminated previously. Three months' suspension of grazing could not protect cattle from infection in a pasture most severely contaminated previously. D. viviparus was eradicated completely by the renovation of pasture.
In 1975, 39 young dairy cows were placed on an uncultivated grassland in Yamagata Prefecture for 5 days in August and 11 days in September. As a result, 29 cows died over a period from September 12 to October 2. They and severely affected cows manifested an increase in ascites, subcutaneous edema, low body temperature, abnormal cardiac function, low blood calcium level, high serum urea-nitrogen level, glycosuria, and aciduria. The dead cows presented an especially high urea-nitrogen level ranging from 186 to 281 mg/dl and indicating uremia induced by renal insufficiency. Histological changes were particularly remarkable in the kidney. In the uriniferous tubules, necrotic epithelial cells were shed and protein-like, hyaline, and crystalline substances present in the lumen. The amount of crystalline substance was much smaller than that reported in the case of oxalate poisoning. Hypoplasia of erythroblastic cells in the bone marrow was different from that observed in bracken poisoning. Such a bovine disease as affecting the kidney chiefly and exhibiting a high fatality was reported for the first time in Japan.
The gel precipitin test and reticuloendotheliosis virus (REV) isolation were carried out with antigen of REV strain T on 309 chicken sera collected from 32 flocks in 1964-65 (group A) and on 430 chicken sera from 42 flocks in 1974-75 (group B). Positive results were obtained from 5.2% of the sera and 25.0 % of the flock of group A and 2.6% of the sera and 11.9% of the flock of group B. It was clarified that REV was present in Japan already in 1964. Antibody was positive in 32.9%, on the average, of the flocks surveyed. In all the positive cases of the gel precipitin test, the precipitation line was completely agreeable with that of immune serum to REV strain T. These cases were also positive for the indirect fluorescent antibody technique.